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Edited By Neil Roy Connelly MD Professor of Anesthesiology Tufts University School of Medicine; Director of Anesthesia Research, Department of Anesthesiology, Baystate Medical Center, Springfield, Massachusetts David G. Silverman MD Professor and Director of Clinical Research Department of Anesthesiology, Yale University School of Medicine; Medical Director of Pre-Admission Testing, Yale–New Haven Hospital, New Haven, Connecticut
Contributing Authors Contributors Tim Abbott DO Resident in Anesthesiology Department of Anesthesiology, Baystate Medical Center, Springfield, Massachusetts Neil Roy Connelly MD Director of Anesthesiology Research Baystate Medical Center, Springfield, Massachusetts; Professor of Anesthesiology, Tufts University School of Medicine Katharine O'Donnell Freeman MD Assistant Section Chief, Pediatric Anesthesia Baystate Medical Center, Springfield, Massachusetts; Assistant Professor, Tufts University School of Medicine Kamel H. Ghandour MD
Anesthesiologist The Stamford Hospital, Stamford, Connecticut David Han MD Anesthesiology Resident University of California, Los Angeles, Medical Center, Los Angeles, California Wandana Joshi DO Medical Director, Anesthesiology Holyoke Medical Center, Holyoke, Massachusetts Matthew R. Keller DO Anesthesiology Resident Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania Brian Kiessling MD Chief of Anesthesia Northwest Michigan Surgery Center, Traverse City, Michigan Albert Lim DO Resident in Anesthesiology Department of Anesthesiology, Baystate Medical Center, Springfield, Massachusetts Tanya Lucas MD Section Chief, Obstetrical Anesthesia Baystate Medical Center, Springfield, Massachusetts, Assistant Professor of Anesthesiology, Tufts University School of Medicine Karthik Raghunathan MD, MPH Department of Anesthesiology and Critical Care, Baystate Medical Center, Springfield, Massachusetts; Assistant Professor of
Anesthesiology, Tufts University School of Medicine Armin Rahimi DO Pain Management Services, South County Anesthesia, St. Anthony's Medical Center, St. Louis, Missouri Stelian Serban MD Assistant Professor of Anesthesiology and Pain Medicine; Director of Acute and Chronic Inpatient Pain Service Mount Sinai Medical Center, New York, New York Lakshmi Priya Yalavarthy MD Resident in Anesthesiology Department of Anesthesiology, Baystate Medical Center, Springfield, Massachusetts
Dedication THIS BOOK IS DEDICATED TO OUR WIVES, ANN GIANCASPRO CONNELLY AND SALLY KNIFFIN, TO OUR CHILDREN, KEVIN MATTHEW AND ELLEN ALEKSANDRA CONNELLY AND TYLER AND CHARLOTTE SILVERMAN, TO MARY M. CONNELLY AND HENRIETTA SILVERMAN, AND TO THE LATE ARTHUR SILVERMAN AND BROTHER ROY MOONEY, F. M. S.
Preface One of the best ways to judge a book is by the company it keeps. Thus, even before it hits the bookstore shelves, Review of Clinical Anesthesia is a “winner.” This totally revised work, which parallels the new (sixth) edition of Clinical Anesthesia, enjoys a distinguished position on a CDROM along with Clinical Anesthesia and other significant texts in the field of anesthesiology. As stated in the introductions to the previous editions of this review book, the amount of information related to our specialty appears to be growing exponentially; even a carefully honed text such as Clinical Anesthesia can seem quite imposing. At times, the reader would like to pause and see what he or she has learned or should learn. These factors were the impetus behind the development of Review of Clinical Anesthesia. In its simplest form, the multiple-choice questions in this text can be used as a means of self-assessment before taking a written examination. However, we feel that this book may be of even greater benefit if it is incorporated throughout one's studies; a pretest will help the novice as well as the expert focus his or her reading; a posttest will allow one to assess self-mastery of most relevant material. The fifth edition of this text has benefited from the extensive updating of the parent text, Clinical Anesthesia. This has led to our revision of the material in virtually every chapter, as well as to the addition of several new chapters. As was the case in recent editions, each answer includes a heading and a page number that refer the reader to a section in Clinical Anesthesia. This information can be used to direct the reader to a more extensive discussion of the subject matter addressed in the question. Neil Roy Connelly MD David G. Silverman MD
Acknowledgments The generation of the questions in this text could not have been accomplished without the dedicated efforts the secretarial staffs of our respective institutions. We appreciate the efforts of the members of the staff at Lippincott Williams & Wilkins who were vital to the organization and completion of this text. We would like to acknowledge the swift and excellent assistance of Nicole Dernoski. We also wish to thank the editors (Drs. Paul Barash, Bruce Cullen, Robert Stoelting, Michael Cahalan, and Christine Stock) and authors of Clinical Anesthesia for, once again, providing us with such a fine source of material. Their careful attention to detail and relevance have facilitated our efforts. We also would like to express our appreciation to our coauthors, whose assiduous efforts have enabled us to assemble a detailed yet cohesive series of questions and answers. Mostly, we would like to thank our families, who waited patiently as we waded through pages of text in search of the questions.
FRONT OF BOOK
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[+] Editors [+] Contributing Authors - Dedication - Preface - Acknowledgments TABLE OF CONTENTS
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Section I - Introduction to Anesthesiology -
Chapter 1 - History of Anesthesia -
Chapter 2 - Scope of Practice -
Chapter 3 - Occupational Health -
Chapter 4 - Anesthetic Risk, Quality Improvement and Liability [-]
Section II - Scientific Foundations of Anesthesia -
Chapter 5 - Mechanisms of Anesthesia and Consciousness -
Chapter 6 - Genomic Basis of Perioperative Medicine -
Chapter 7 - Pharmacologic Principles -
Chapter 8 - Electrical and Fire Safety -
Chapter 9 - Experimental Design and Statistics [-]
Section III - Anatomy and Physiology -
Chapter 10 - Cardiovascular Anatomy and Physiology -
Chapter 11 - Respiratory Function -
Chapter 12 - Immune Function and Allergic Response -
Chapter 13 - Inflammation, Wound Healing and Infection -
Chapter 14 - Fluids, Electrolytes, and Acid Base Physiology -
Chapter 15 - Autonomic Nervous System -
Chapter 16 - Hemostasis and Transfusion Medicine [-]
Section IV - Anesthetic Agents, Adjuvants, and Drug Interaction -
Chapter 17 - Inhaled Anesthetics -
Chapter 18 - Intravenous Anesthetics -
Chapter 19 - Opioids -
Chapter 20 - Neuromuscular Blocking Agents -
Chapter 21 - Local Anesthetics -
Chapter 22 - Drug Interactions [-]
Section V - PreAnesthetic Evaluation and Preparation -
Chapter 23 - Preoperative Patient Assessment and Management -
Chapter 24 - Malignant Hyperthermia and Other Inherited Disorders -
Chapter 25 - Rare and Co-existing Diseases -
Chapter 26 - The Anesthesia Workstation and Delivery Systems [-]
Section VI - Anesthetic Management -
Chapter 27 - Standard Monitoring Techniques -
Chapter 28 - Echocardiography -
Chapter 29 - Airway Management -
Chapter 30 - Patient Positioning and Related Injuries -
Chapter 31 - Monitored Anesthesia Care -
Chapter 32 - Ambulatory Anesthesia -
Chapter 33 - Office Based Anesthesia -
Chapter 34 - Anesthesia Provided at Alternate Sites -
Chapter 35 - Anesthesia for the Older Patient -
Chapter 36 - Anesthesia for Trauma and Burn Patients -
Chapter 37 - Epidural and Spinal Anesthesia -
Chapter 38 - Peripheral Nerve Blockade [-]
Section VII - Anesthesia for Surgical Subspecialties -
Chapter 39 - Anesthesia for Neurosurgery -
Chapter 40 - Anesthesia for Thoracic Surgery -
Chapter 41 - Anesthesia for Cardiac Surgery -
Chapter 42 - Anesthesia for Vascular Surgery -
Chapter 43 - Obstetrical Anesthesia -
Chapter 44 - Neonatal Anesthesia -
Chapter 45 - Pediatric Anesthesia -
Chapter 46 - Gastrointestinal Disorders -
Chapter 47 - Anesthesia and Obesity -
Chapter 48 - Hepatic Anatomy, Function and Physiology -
Chapter 49 - Endocrine Function -
Chapter 50 - Anesthesia for Otolaryngologic Surgery -
Chapter 51 - Anesthesia for Ophthalmologic Surgery -
Chapter 52 - The Renal System and Anesthesia for Urologic Surgery -
Chapter 53 - Anesthesia for Orthopedic Surgery -
Chapter 54 - Transplant Anesthesia [-]
Section VIII - Perioperative and Consultative Services -
Chapter 55 - Post Anesthesia Recovery -
Chapter 56 - Critical Care Medicine -
Chapter 57 - Acute Pain Management -
Chapter 58 - Chronic Pain Management -
Chapter 59 - Cardiopulmonary Resuscitation -
Chapter 60 - Disaster Preparedness
Chapter 1 History of Anesthesia 1. Ancient Egyptian pictographs display nerve compression to possibly produce regional anesthesia during upper extremity surgery. A. True B. False 1. A. True. Ancient Egyptian pictographs from approximately 3,000 BC display images of nerve compression during upper extremity surgery. One pictograph shows a brachial plexus being compressed, and another shows antecubital fossa nerve compression; both surgeries were presumably done on alert patients and done on the hand. (See page 4: Physical and Psychological Anesthesia.) 2. In the 17th century, Marco Aurelio Severino described using snow to create anesthesia at a surgical site. A. True B. False 2. A. True. People have long recognized that cold temperatures produce insensibility to pain. Remarkably, in the Middle Ages, people attempted to apply the property of cold to perform surgery as an early form of cryo-anesthesia. (See page 4: Physical and Psychological Anesthesia.) 3. During the 9th century, a soporphic sponge was used to provide pain relief during surgery. What ingredient(s) were boiled together and cooked into this sponge? A. Mandrake leaves B. Black nightshade C. Poppies D. All of the above
3. D. In the 1st century, mandragora was recognized to produce analgesia. Historically, a soporific sponge was used to produce an acceptable level of surgical analgesia. This sponge had various recipe forms depending on the producer; however, all of them included mandrake leaves, black nightshade, and poppies boiled together to form a sponge that was administered to a patient after reconstitution in hot water. (See page 4: Early Analgesics and Soporifics.) 4. Nitrous oxide has the ability to produce lightheadness. Some thrill seekers intentionally expose themselves to nitrous oxide as a diversion. Who is credited with first preparing nitrous oxide by heating ammonium nitrate with iron filings? A. Dr. Thomas Beddoes B. Mr. Joseph Priestley C. Dr. Humphry Davy D. Dr. Horace Wells E. Dr. Valerius Cordus 4. B. Nitrous oxide was first prepared in 1773 by the British clergyman and scientist Joseph Priestley. Priestley prepared several other gases during his investigations, the most notable being isolated oxygen. Davy and Wells performed later observations and experiments with nitrous oxide, and Valerius Cordus is credited with having distilled diethyl ether (sweet oil of vitriol) in the 16th century. (See page 4: Inhaled Anesthetics.) 5. Who is credited with the earliest documented use of diethyl ether for painless surgery? A. Dr. Crawford W. Long B. Dr. Henry Hill Hickman C. Dr. William T.G. Morton D. Dr. Horace Wells E. Dr. Charles T. Jackson 5. A. Although Dr. William Morton has been credited with introducing diethyl ether as a successful anesthetic in the public arena on October
16, 1846, Dr. Crawford W. Long of Athens, Georgia, has the distinction of the first documented successful use of ether in the surgical setting. Dr. Long first administered ether preoperatively on March 30, 1842, but he neglected to make his findings known until 1849, well after Dr. Morton's demonstration. (See page 5: Public Demonstration of Ether Anesthesia.) 6. In 1845, an anesthetist gave a public demonstration of nitrous oxide at the Massachusetts General Hospital. Even though the patient was unaware, he still cried out during the surgery. This anesthetist thus became the first in modern anesthesia to hear a surgeon say, “Give him more gas!” Who was this man? A. Dr. Crawford W. Long B. Dr. Henry Hill Hickman C. Dr. William T.G. Morton D. Dr. Horace Wells E. Dr. Charles T. Jackson 6. D. Dr. Horace Wells has the distinction of being the first person in the history of modern anesthesia to have a patient cry out and move during his public demonstration of nitrous oxide. Although the patient did not recall the surgery, Dr. Wells undoubtedly had to listen to the surgeon complain about the patient not holding still during the surgery. Modern anesthetists in the 21st century no longer have this problem, of course. (See page 5: Almost Discovery.) 7. On October 16, 1846, there was a public demonstration of ether at the Massachusetts General Hospital. The man who demonstrated this not only established ether as an effective anesthetic he also managed to firmly establish in surgeons' minds that “the anesthetist is always late!” Who was the anesthetist? A. Dr. Crawford W. Long B. Dr. Henry Hill Hickman C. Dr. William T.G. Morton D. Dr. Horace Wells E. Dr. Charles T. Jackson
7. C. On “ether day,” October 16, 1846, Dr. William Morton gave a public display of ether for surgical anesthesia to Edward Abbott. The surgeon was Dr. John Warren. Dr. Warren will always be remembered as the first modern surgeon to complain in public that the anesthetist was late. (See page 5: Public Demonstration of Ether Anesthesia.) 8. Who published the use of chloroform for anesthesia during labor and childbirth in the Lancet in 1847? A. Dr. James Young Simpson B. Dr. Virginia Apgar C. Dr. William Morton D. Dr. Joseph Clover E. Queen Victoria 8. A. Although Dr. Simpson, an accomplished obstetrician in Edinburgh, Scotland, had been a champion of the use of ether and chloroform anesthesia for labor and childbirth, the relief of obstetric pain had long been discouraged on prevailing religious grounds. It was not until Dr. John Snow, an English contemporary of Dr. Simpson, administered chloroform to a laboring Queen Victoria that widespread acceptance of obstetric anesthesia came into being. As head of the Church of England, the queen's endorsement of the practice ended the debate as to the appropriateness of such anesthetics. (See page 6: Chloroform and Obstetrics.) 9. Which notable advancement in the field of anesthesiology can be credited primarily to work done by American surgeon Dr. Joseph O'Dwyer in the mid-1880s? A. Tracheal intubation B. Central venous cannulation C. Direct laryngoscopy D. Brachial plexus conduction block E. Anesthetic record 9. A. Although elective oral tracheal intubation was first performed by Scottish surgeon William Macewen in 1878, it was the work of American
surgeon Dr. Joseph O'Dwyer that popularized the technique. In 1885, Dr. O'Dwyer developed a set of metal laryngeal tubes, which he inserted blindly between the vocal cords of children with diphtheritic crises as an alternative to hasty tracheotomies. Three years later, he developed a rigid endotracheal tube with a conical tip, which allowed positivepressure endotracheal ventilation to be used during thoracic procedures. (See page 7: Tracheal Intubation.) 10. Which pioneer in the field of anesthesiology can be credited with P the development of the cuffed endotracheal tube? A. Dr. Ralph Waters B. Dr. Joseph O'Dwyer C. Dr. Arthur Guedel D. Dr. Elmer McKesson E. Ivan Magill 10. C. In 1926, Dr. Arthur Guedel began a series of experiments that led to the introduction of the cuffed endotracheal tube. His goal was to combine tracheal anesthesia with the closed-circuit technique recently refined by Waters. To showcase the utility of these new tubes, Dr. Guedel performed a series of demonstrations with his own dog, “Airway,” who he anesthetized and submerged underwater while using the cuffed endotracheal tube. (See page 7: Tracheal Intubation.) 11. When Dr. Ralph Waters intentionally ventilated only one lung, what airway instrument did Dr. Arthur Guedel propose? A. The fiberoptic bronchoscope B. The elastic intubating stylet C. Nasal endobronchial tubes D. Double-cuffed single-lumen tubes E. Double-lumen endobronchial tubes 11. D. Dr. Ralph Waters described a bronchial intubation and hypothesized that intentional endobronchial intubation could facilitate surgery on the opposite lung. He related this to Dr. Arthur Guedel, leading to the design of the single-lumen, double-cuff modification of
the emerging cuffed airway tube. Later, Dr. Frank Robertshaw popularized the double-lumen endobronchial tube. Since then, there have been several modifications and new techniques described for lung isolation; however, the basic reasoning remains the same. (See page 7: Tracheal Intubation.) 12. Dr. Roger Bullard became frustrated by failed attempts to visualize the larynx of a patient with Pierre-Robin syndrome. He then developed a laryngoscope called the: A. Wu-scope B. Bullard scope C. Combi-Laryngoscope D. LMA camerascope E. Anesthesia kaleidoscope 12. B. Dr. Roger Bullard developed the Bullard laryngoscope in response to frustration with the acute angle observed in a patient with PierreRobin syndrome. This laryngoscope incorporated fiberoptic bundles that lie beside a curved blade and allowed the user to observe the larynx lying at 90 degrees from the mouth. (See page 8: Advanced Airway Devices.) 13. With his radical thinking, Dr. Archie Brain made what contribution to airway management? A. Patil face mask B. Laryngeal mask airway C. Wu-scope D. Flexible fiberoptic bronchoscope E. Bullard laryngoscope 13. B. Dr. Archie Brain produced and made popular the laryngeal mask airway after he realized that it was an effective means of ventilating and delivering anesthetics to a patient. Shigeto Ikeda developed the first flexible fiberoptic bronchoscope. Dr. Roger Bullard developed the Bullard laryngoscope to “see around the corner” of the airway. The Wuscope was later developed to improve on the idea of the Bullard
laryngoscope. The Patil Face Mask, developed by Dr. Vijay Patil, was developed to oxygenate the anesthetized patient while a flexible fiberoptic bronchoscope is used to intubate the airway. All of these innovations were prompted by the need to manage patients with challenging, difficult airways. (See page 8: Advanced Airway Devices.) 14. Dr. Elmer McKesson is credited with the innovation of which of the following features of modern-day anesthesia machines? A. Oxygen fail-safe valve B. Flow-ratio system C. Oxygen flush valve D. Variable bypass vaporizers E. Partial rebreathing circuits 14. C. Dr. Elmer McKesson, one of the first specialists in anesthesiology in the United States, developed a series of gas machines. Because of concerns over inflammable anesthetics, Dr. McKesson popularized anesthetic inductions with 100% nitrous oxide, with titration of small volumes of oxygen as the anesthetic progressed. Dr. McKesson developed the oxygen flush valve to add oxygen quickly to the system in the event that the resultant cyanosis became too profound. (See page 9: Early Anesthesia Delivery Systems.) 15. In 1907, the Draeger “Pulmotor” was introduced as the first intermittent positive-pressure ventilator. A. True B. False 15. A. True. Mine rescue workers and firefighters were provided with early forms of positive-pressure mechanical ventilators to help resuscitating injured patients. The first marketed device, the “Pulmotor,” was produced by Draeger in 1907. Afterward, the European polio epidemic inspired further refinements in mechanical ventilation. (See page 10: Ventilators.) 16. During World War II, British aviation researchers began research on devices to improve the supply of oxygen that was provided to pilots flying at high altitude in unpressurized aircraft. This research
led to perhaps the most important technological advance ever made in monitoring the well-being and safety of patients during anesthesia. What is this monitoring system? A. Continuous capnography B. Electrocardiography C. Mass spectrometry D. Oxygen sensors E. Pulse oximetry 16. E. Pulse oximetry, described by Dr. Severinghaus as “the most important technologic monitoring advance in the history of anesthesia,” was developed by Takuo Aoyagi, a Japanese engineer. His work was a refinement of earlier investigations performed by Glen Millikan, an American physiologist, that pertained to oximetric sensors for fighter pilots during World War II. (See page 12: Electrocardiography, Pulse Oximetry, and Capnography.) 17. Trichloroethylene, a nonexplosive volatile anesthetic, releases what compound when it is warmed in the presence of soda lime? A. Compound X B. Compound A C. Factor X D. Phosgene E. Ethyl chloride 17. D. Trichloroethylene was a widely used nonexplosive volatile anesthetic. However, it was found to be toxic to multiple organ systems when administered for prolonged periods or at high concentrations. When the gas is heated in the presence of soda lime, it produces phosgene as a byproduct. When phosgene is inhaled, it reacts with water in the lungs to form hydrochloric acid and carbon monoxide, with resultant pulmonary edema. Phosgene was used extensively during World War I as a choking agent. Among the chemicals used in the war, phosgene was responsible for the majority of deaths. (See page 13: Inhaled Anesthetics.)
18. What anesthetic, although popular in the mid-20th century, was abandoned after it was learned that dose-related nephrotoxicity was associated with its prolonged use? A. Chloroform B. Methoxyflurane C. Ether D. Enflurane E. Halothane 18. B. Over a protracted period, methoxyflurane use leads to increased serum fluoride concentrations and nephrotoxicity. Before this was discovered, methoxyflurane was a very popular volatile anesthetic in the 1960s. (See page 13: Inhaled Anesthetics.) 19. The cardiovascular effects of which drug became widely appreciated only after a series of fatalities among military casualties during World War II? A. Curare B. Thiopental C. Fentanyl D. Halothane E. Cyclopropane 19. B. Thiopental was synthesized in 1932 by Tabern and Volwiler of the Abbott Company and was first administered to a patient at the University of Wisconsin in March 1934. The cardiovascular depressive effects of thiopental were widely appreciated only after its use led to fatalities among civilians and soldiers during World War II. After these experiences, fluid replacement therapy was used more aggressively, and thiopental was administered with greater caution. (See page 14: Intravenous Anesthetics.) 20. What medication introduced in the late 20th century suppressed pharyngeal reflexes, produced anesthesia rapidly, had antiemetic properties, allowed patients to wake promptly, and popularized total intravenous anesthetic techniques?
A. Ketamine B. Propofol C. Meperidine D. Chlorpromazine E. Droperidol 20. B. Propofol combined with variable-duration paralytics and fasteracting narcotics made total intravenous anesthesia techniques more accessible. Propofol's antiemetic property, along with a ceiling contextsensitive half-life, makes it a popular anesthetic agent. (See page 14: Intravenous Anesthetics.) 21. Oncologists identified the antiemetic properties of what medication when dealing with intracranial edema from tumors? A. Antihistamines B. Propofol C. Droperidol D. Corticosteroids E. Promethazine 21. D. Corticosteroids decrease intracranial edema in patients with mass lesions and tumors. They also reduce nausea. This antiemetic effect was quickly recognized by anesthesiologists. (See page 18: Antiemetics.) 22. Dr. Leonard Corning is remembered for coining the term “spinal anesthesia” and for performing a neuraxial block on a man “addicted to masturbation.” A. True B. False 22. A. Dr. Corning assessed the effects of cocaine injected into the lumbar neuraxial space. He attempted to perform a therapeutic neuraxial block on a man “addicted to masturbation,” and because Dr. Corning did not describe an escape of fluid, we assume that an epidural injection of cocaine was performed. We do not know if the patient was “cured” of his addiction. (See page 19: Regional Anesthesia.)
P 23. Drs. Bier and Hildebrandt performed a successful spinal anesthetic when Dr. Hildebrandt did not feel pain after his legs were hit with a hammer and his testicles were pulled. How did these physicians celebrate their success? A. Wine and cigars B. Going out to the opera and then a “cabaret” C. By visiting an opium den in Kiel, Germany D. With more hammers 23. A. The first clearly defined spinal anesthetic involved the release of a large volume of cerebrospinal fluid (CSF) through large-bore needles. The observation of CSF as an end point is still used. This led to the first described postdural puncture headache. Drs. Bier and Hildebrandt erroneously attributed the violent headaches to their celebratory wine and cigars. (See page 19: Regional Anesthesia.) 24. Who described a continuous spinal anesthetic technique in or around 1940? A. Dr. Heinrich Quincke B. Dr. August Bier C. Dr. Theodor Tuffier D. Dr. William Lemmon E. Dr. Richard Hall 24. D. Dr. William Lemmon described the use of a malleable silver needle to puncture the dura. Local anesthetic was introduced as needed through a hole in the operating table mattress. Later, the same technique was described by Dr. Waldo Edwards and Dr. Robert Hingson for continuous caudal anesthesia in obstetric patients. (See page 19: Regional Anesthesia.) 25. Dr. Achille Dogliott described what anesthetic technique in 1931? A. Intravenous regional anesthesia of the arm B. Loss of resistance to identify the epidural space
C. Blind nasotracheal intubation D. Cervical spinal anesthesia E. Regional block of the ankle 25. B. Dr. Achille Dogliotti of Turin, Italy, wrote a classic study that made the epidural technique well known. Dr. Dogliotti identified it by the loss-of-resistance technique. (See page 19: Regional Anesthesia.) 26. Who first described the technique of intravenous regional anesthesia in 1908? A. Dr. Harvey Cushing B. Dr. August Bier C. Dr. Carl Koller D. Dr. Leonard Corning E. Dr. Heinrich Braun 26. B. Intravenous regional anesthesia was first reported in 1908 by Dr. August Bier, who used a technique in which procaine was injected into a vein of the upper limb between two tourniquets. The technique was not widely used in the clinical setting until 1963, when Dr. Mackinnon Holmes modified the block by exsanguination before applying a single proximal cuff. (See page 19: Regional Anesthesia.) 27. Who created the first clinic for the treatment of chronic pain in the United States? A. Dr. Emery Rovenstine B. Dr. Frederick Cotton C. Dr. John Snow D. Dr. John Booka E. Dr. Ambrose Bierce 27. A. Dr. Emery Rovenstine continued the work of Dr. Gaton Labat and his colleagues. At the Bellevue Hospital in New York City, he used invasive techniques to lyse sensory nerves and to inject local anesthetics in an attempt to treat chronic pain. This association of physicians
focused on pain management was the first of its kind in North America. (See page 19: Regional Anesthesia.) 28. Dr. Jean Baptiste Denis first attempted blood transfusion in 1667. His patient received blood from: A. A slave B. A cow C. A lamb D. Dr. Denis himself E. A horse 28. C. Amazingly, Dr. Jean Denis, the court physician to Louis XIV, first transfused blood from a lamb into a patient, who benefited from the transfusion. It is reported that the following attempts at interspecies were not successful, and the transfusion of blood in humans was banned for religious reasons for more than 100 years in Western Europe. (See page 22: Transfusion Medicine.) 29. This person is credited with advancing American anesthesiology professional societies in the early 20th century. He edited the precursor journal to Anesthesia and Analgesia, acted as an ambassador to Europe for American anesthesiology, and founded the International Anesthesia Research Society (IARS). Who was this person? A. Dr. Harvey Cushing B. Dr. Benjamin Franklin C. Dr. Francis McMechan D. Dr. Karl Landsteiner E. Dr. Carl Gauss 29. C. Dr. Francis McMechan retired from active anesthesia practice in Cincinnati in 1915 because of severe rheumatoid arthritis. Afterward, he dedicated himself to editing the precursor to the anesthesiology journal Anesthesia and Analgesia (at the time, it was called Current Researches in Anesthesia and Analgesia). In addition, he helped establish an international society for anesthesia research (the IARS) while acting as
an ambassador in Europe for American anesthesiology. One byproduct of his efforts was the establishment of the International College of Anesthetists, which certified early anesthesiologists and helped raise the standards of anesthesiology quality in the early 20th century. (See page 23: Organized Anesthesiology.) 30. Dr. Ralph Waters became frustrated by the low-quality training of anesthesia providers, established the first postanesthetic recovery rooms, and became the first American professor of anesthesiology. Where was he a professor? A. University of Michigan B. St. Louis University C. University of Tamaulipas D. University of Wisconsin E. Tufts University 30. D. Dr. Ralph Waters became the first American academic professor of anesthesiology at the University of Wisconsin's medical school in 1927, where he established an anesthesiology residency-training program. Dr. Waters attracted motivated and talented people to the department, and he fostered many of the qualities that are common in modern academic anesthesiology departments. International experts at the time visited this department and were influenced by it. (See page 23: Organized Anesthesiology.) For questions 31 and 32, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 31. In the late 19th and early 20th centuries, which of the following explosive volatile anesthetics were in use? 1. Chloroform 2. Ether 3. Cyclopropane 4. Nitrous oxide
31. A. Both ether and chloroform were known to be flammable gases and to be explosion hazards. Cyclopropane (also called trimethylene) is an explosive, colorless gas first used in 1934 as a volatile general anesthetic. Both induction and emergence from cyclopropane anesthesia were reported to be usually rapid and smooth, but because it is flammable and could be a source of explosion in the operating area, it was replaced by nonflammable gases. Nitrous oxide can support combustion, but it is not explosive. (See page 13: Inhaled Anesthetics.) 32. Which of the following statements regarding the history of cocaine as an anesthetic is/are TRUE? 1. Cocaine was the first effective local anesthetic. 2. Its utility as a local anesthetic was first introduced to the medical community by Dr. Carl Koller in 1884. 3. Cocaine was the agent used in the first successful spinal anesthetic. 4. Although its local anesthetic actions were well recognized, cocaine was not used in surgical procedures until 1911. 32. A. The anesthetic properties of cocaine, an extract of the coca leaf, had been known for centuries before its formal introduction in 1884 by Dr. Carl Koller. Soon thereafter, cocaine gained widespread acceptance as an anesthetic agent for surgical procedures involving the mucous membranes, such as the eyes, mouth, nose, larynx, trachea, and rectum. Cocaine was also used by Dr. Leonard Corning for the first successful spinal anesthetic in 1885. (See page 19: Regional Anesthesia.)
Chapter 2 Scope of Practice 1. Accreditation from The Joint Commission lasts for how many years? A. 1 B. 2 C. 3 D. 4 E. 5 1. C. Full accreditation from The Joint Commission lasts for 3 years. (See page 31: Establishing Standards of Practice and Understanding the Standard of Care.) 2. The main goal of a managed care organization (MCO) is to attempt to manage what aspects of the health care system? A. Number of facilities in a geographic area B. Utilization of services within a patient population C. Outline of the best management for each particular condition D. Ensuring that physicians are managed to improve physician income E. Being a division of the National Institutes of Health whose goal is the development of universal coverage 2. B. MCOs are companies that provide health care for large populations. Their main goal is to attempt to control costs through providing appropriate care, negotiating for the lowest prices on services, and restricting access to more expensive services such as operative procedures. (See page 45: New Practice Arrangements.) 3. All of the following factors are the benefits of an anesthesia preoperative clinic EXCEPT:
A. Increase in the efficiency of operating rooms B. Financial savings for the institution C. Centralization of pertinent information, including consults, financial data, and diagnostic and laboratory information D. Patient and family education on the process, surgery, and postsurgical considerations E. Ability to schedule presurgical evaluation at the last minute because of the streamlined process of the clinic 3. E. The anesthesia preoperative clinic allows the running of a more efficient operating room schedule. It reduces last-minute cancellations, shotgun ordering of laboratory work, and unnecessary preoperative specialty consultation. Early identification of certain problems requiring special care on the day of surgery (e.g., blocks, pulmonary artery catheters) leads to fewer unanticipated delays. All relevant patient information can be centralized to one location. However, all of these benefits are optimized when the patient is seen relatively early in relation to the day of surgery. Early recognition of patients requiring further workup allows time for another patient to fill the vacant block in the schedule. (See page 52: Preoperative Clinic.) 4. All of the following facts are true EXCEPT: A. Standard of care is the conduct and skill of a prudent practitioner that can be expected by a reasonable patient. B. Courts have traditionally relied on medical experts knowledgeable about the point in question to give opinions as to what the standard of care is. C. A less objective way of determining the standard of care is to review the published standards of care, guidelines, practice parameters, and protocols established by the American Society of Anesthesiology. D. The standard of care is what a jury says it is. E. Expert witnesses can establish the standard of care. 4. C. The standard of care is the conduct and skill of a prudent practitioner that can be expected by a reasonable patient. Expert
witnesses can define it. This was traditionally the method of establishing the standard of care. The problem with this method was that both parties could have expert witnesses, which can support the two opposing sides, thereby making the process subjective. The more objective way of determining the standard of care is reviewing the published standards of care, guidelines, practice parameters, and protocols established by a national organization such as the American Society of Anesthesiologists. The above two methods are the two main sources for information that a jury has available to them to establish the standard of care. (See page 31: Establishing Standards of Practice and Understanding the Standard of Care.) For questions 5 to 12, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 5. Which of the following statements regarding “claims-made” insurance is/are TRUE? 1. Policies cover all malpractice claims made while the insurance is being paid. 2. Policies are very expensive during the first year of practice. 3. Tail coverage is a hidden expense with claims-made policies. 4. Claims-made policies are more expensive for insurance companies because they have a longer period in which they are exposed to possible claims. 5. B. The two primary types of malpractice insurance are occurrence and claims-made insurance. An “occurrence” insurance policy means that if the policy was in force at the time of the occurrence of an incident resulting in a claim, whenever that claim might be filed, the practitioner would be covered. “Claims-made” insurance only covers claims that are filed while the insurance is in force. This kind of insurance is relatively inexpensive during the first year because claims typically take some time to be filed. However, if the physician simply discontinues a claims-made policy (e.g., by changing insurers or leaving a given practice) and a claim is filed the next year, there will be no insurance coverage. Therefore, the physician leaving a claims-made policy must secure “tail coverage” for claims filed after the physician is
no longer primarily covered by that insurance policy. (See page 36: Malpractice Insurance.) 6. Establishing standards of care, practice parameters, and guidelines in anesthesia practice affords individuals with which of the following benefits? 1. Improvement in quality of care 2. Providing the basis for legal defense in malpractice cases 3. Guiding thought processes through difficult clinical scenarios 4. Fulfilling legal mandates 6. A. Standards of care, practice guidelines, and parameters have been increasingly used over the past few decades. The impetus for their increased use centers primarily on the improvement of quality of care for patients. American Society of Anesthesiologists (ASA) Monitoring Standards of Care is an excellent example of standard of care guidelines, and the ASA Difficult Airway Algorithm is an outstanding example of practice guidelines. These guidelines, if followed, typically improve patient outcomes and cost effectiveness by reducing unnecessary tests and ineffective treatments. Because experts in the field usually develop these standards, they constitute a powerful legal defense in light of a malpractice suit. Practicing outside the standards of the specialty requires one to justify one's actions and decisions. Standards of care, practice parameters, and practice guidelines are not legally mandated. (See page 31: Establishing Standards of Practice and Understanding the Standard of Care.) 7. After a critical adverse event occurs, which of the following should be implemented? 1. Immediately obtain appropriate help. 2. Involve the risk management department in the hospital only if a suit is filed. 3. Record any additions or alterations of the facts in the chart as amendments. 4. Chart the event, including the facts of the events and speculations regarding the cause of the incident.
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7. B. After the identification of a critical event, help should be called to minimize the sequelae of the event. If permanent injury occurs, early involvement of the anesthesia department, hospital administration, risk management department, and insurance company is essential. Charting of the event is critical. Only facts should be included in the chart. No speculation regarding the cause or who is to blame should be recorded. Any change to the chart's original documentation should be recorded as an amendment and labeled as such, with an indication regarding why such an amendment was necessary. (See page 36: Malpractice Insurance.) 8. Computer scheduling of cases has advantages over handwritten systems in which of the following ways? 1. Historical precedents of time for procedures can prevent overbooking. 2. It can result in a decrease of staff overtime costs. 3. It can easily generate reports and statistics for future use. 4. It can reduce personal bias in scheduling cases. 8. E. Computer scheduling programs are powerful tools in operating room management. When historical times for procedures are input into the system, the program can prevent optimistic bookings by surgeons and can prevent operating room time from running long and thus requiring payment of overtime. Inputting this type of data can allow the program to generate reports and statistics that will aid in future planning. The program can examine the schedule and determine whether any staff or equipment double booking has occurred, which may not be obvious on a standard ledger schedule. Computer programs require a large commitment to training and data entry. Computerization can also eliminate personal bias in the scheduling of case time. (See page 52: Computerization.) 9. Which of the following regarding the Health Insurance Portability and Accountability Act (HIPAA) of 1996 is/are TRUE? 1. Attention is focused on protected health information. 2. A “privacy officer” must be appointed for each practice group. 3. Patient charts must be locked away overnight.
4. A fax containing patient information does not need any special handling. 9. A. HIPAA requires that attention be focused on protected health information. Each practice group must designate and appoint a “privacy officer.” HIPAA provisions require that patient charts must be locked away overnight. Telephone calls and faxes must be handled specially if they contain identifiable patient information. (See page 47: HIPAA.) 10. Which of the following regarding antitrust considerations is/are TRUE? 1. Antitrust laws involve the rights of individuals to engage in business. 2. The Sherman Antitrust Act is approximately 50 years old. 3. The per se rule is the most frequently applied rule when judging violations. 4. Antitrust laws are concerned with the preservation of competition in a defined marketplace. 10. D. The Sherman Antitrust Act is more than 100 years old. Antitrust laws do not involve the right of individuals to engage in business but rather are solely concerned with the preservation of competition within a defined marketplace. The per se rule, which is rarely applied, makes conduct that obviously limits competition illegal. (See page 43: Antitrust Considerations.) 11. Which of the following is/are TRUE regarding operating room management? 1. Anesthesiologists should develop a leading role among other operating room personnel. 2. Block scheduling appears to be the most efficient manner for scheduling surgical cases and should be used exclusively in the creation of the operating room schedule. 3. Prudent drug selection combined with appropriate anesthesia technique may result in dollars savings.
4. Sharing the responsibility of “running the floor” among all the anesthesiologists is an efficient way to manage the operating room schedule because all anesthesiologists will come to appreciate the nuances of the day-to-day schedule. 11. B. The role of anesthesiologists in operating room management has changed dramatically in the past few years. The current emphasis on cost containment and efficiency necessitates anesthesiologists' involvement in operating room management. Anesthesiologists are in the best position to see the “big picture,” both overall and on any given day. They are best qualified to provide leadership in the operating room because they spend a large portion of their time in the operating room. Surgeons, on the other hand, have commitments to their offices and sometimes to multiple facilities. Block scheduling may work in some facilities that have a large number of surgeons who book far in advance and have very specific office and operating room schedules. However, some degree of open scheduling is necessary, depending on the number of add-on emergencies at a particular facility. Most large institutions use a combination of block scheduling and open scheduling. Prudent drug selection combined with appropriate technique may produce substantial savings. Reducing fresh gas flow from 5 L/min to 2 L/min can save approximately $10 million per year in the United States. Delineating the responsibility of “running the floor” to a select few members of the department provides more consistency in decision making and application of the operating room policies. It helps individuals become very familiar with the nuances of managing the operating room schedule in real time. An individual's personality affects his or her ability in managing difficult surgeons in a consistent and fair manner. (See page 48: Operating Room Management.) 12. In dealing with an adverse event, one must consider which of the following? 1. Establish an “adverse event protocol” in the department in the policies and procedures manual. 2. Establish an “incident supervisor” whose responsibility is to help prevent continuation or reoccurrence of incidents,
investigating incidents, and ensuring documentation while the original anesthesiologists focuses on caring for the patient. 3. The chief of anesthesiology, facility administrator, risk manager, and anesthesiologist's insurance company should be notified in a timely manner. 4. Full disclosure of the events as they are best known is currently believed to be the best presentation. 12. E. It is important to establish an adverse event protocol in the department's policies and procedures manual. When a critical incident occurs, call for help. Establish an “incident supervisor” whose responsibility is to help prevent continuation or reoccurrence of the incident, investigate the incident, and ensure documentation while the original and helping anesthesiologists focus on caring for the patient. Consultants may be helpful and should be called without hesitation. The chief of anesthesiology, facility administrator, risk manager, and anesthesiologist's insurance company should be notified in a timely manner. If the surgeon is involved, he or she should notify the family first, but the anesthesiologist and others (risk managers, legal counsel, or insurance loss control officer) might appropriately be included. Full disclosure of the events as they are best known is currently believed to be the best presentation. Any attempt to conceal or shade the truth will only confound an already difficult situation. There is a new movement in medical risk management advocating immediate full disclosure to the victim, including “confessions” of medical judgment and performance errors with attendant apologies. All discussions with the patient and family should be carefully documented in the medical record. Judgments about causes or responsibilities should not be made. One should never change an existing entry in the medical record. Only the facts, as they are known, should be stated. (See page 37: Response to an Adverse Event.)
Chapter 3 Occupational Health 1. Which of the following substances found in latex gloves is responsible for the majority of generalized allergic reactions? A. Preservatives B. Polyisoprenes C. Protein content D. Accelerators E. Powder 1. C. Latex is a complex substance that contains polyisoprenes, lipids, phospholipids, and proteins. Numerous additional substances, including preservatives, accelerators, antioxidants, vulcanizing compounds, and lubricating agents, are added to latex gloves. The protein content is responsible for causing the majority of allergic reactions. These reactions are exacerbated by the presence of powder that enhances the potential of latex particles to aerosolize and spread to the respiratory system of personnel and to environmental surfaces during donning and removing gloves. (See page 62: Physical Hazards: Latex.) 2. Which of the following statements concerning tuberculosis (TB) is FALSE? A. It is transmitted by bacilli carried on airborne particles. B. Using any face mask will prevent infection. C. Patients with HIV are at increased risk for infection. D. If surgery is required, bacterial filters (high-efficiency particulate filters) should be used on the anesthetic breathing circuit for patients with TB. E. Elective surgery should be postponed for infected patients.
2. B. Use of a special mask that is fitted to the person wearing it and that is capable of filtering particles 1 to 5 mm in diameter is required to protect health care workers from patients with active TB. (See page 65: Infection Hazards.) 3. Airborne precautions are an effective preventive measure against which of the following infectious agents? A. Cytomegalovirus (CMV) B. Tuberculosis (TB) C. Herpes simplex D. Herpetic whitlow E. All of the above 3. B. Preventive measures for the listed infectious agents are as follows: CMV, standard precautions; TB, airborne precautions and isoniazid or ethambutol for purified protein derivative conversion; herpes simplex, standard precautions and contact precautions if disseminated disease is present; influenza, vaccine, prophylactic antiretrovirals, and droplet precautions. (See page 67: Table 3-3, Prevention of Occupationally Acquired Infections.) 4. Signs of substance abuse inside the hospital include: A. Signing out large quantities of narcotics B. Refusing breaks C. Volunteering to relieve others and taking extra calls D. Disappearing between cases E. All of the above 4. E. Signing out large quantities of narcotics, refusing breaks, volunteering to relieve others, disappearing between cases, weight loss, pale skin, pinpoint pupils, and taking extra calls are all signs of substance abuse. Addicts also have unusual changes in behavior, have sloppy charts, and want to work alone to divert narcotics for personal use. They are difficult to find between cases. Their patients often complain of pain in the recovery room. (See page 76: Table 3-5, Signs of Substance Abuse and Dependence.)
5. All of the following statements about radiation exposure are true EXCEPT: A. The risk of exposure is not influenced by age or gender. B. Because radiation exposure is inversely proportional to the square of the distance from the source, increasing this distance is more universally protective. C. The magnitude of radiation absorbed by the individual is a function of total radiation intensity and time. D. The lead aprons and thyroid collars commonly worn leave many sites exposed to radiation. 5. A. The magnitude of radiation absorbed by individuals is a function of three variables: (1) total radiation exposure, intensity, and time; (2) distance from the source of radiation; and (3) the use of radiation shielding. Unfortunately, the lead aprons and thyroid collars commonly worn leave exposed many vulnerable sites, such as the long bones of the extremities, the cranium, the skin of the face, and the eyes. Because radiation exposure is inversely proportional to the square of the distance from the source, increasing this distance is more universally protective. The risks associated with radiation vary considerably depending on age, gender, and specific organ site exposure. (See page 62: Radiation.) For questions 6 to 15, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 6. Which of the following statements is/are TRUE regarding studies of anesthetic trends in the operating room and effects on fertility and childbearing? 1. Scavenging anesthetic lowers levels in operating rooms. 2. It is difficult to quantify the levels of anesthetic in an operating room. 3. There is a slight increase in the relative risk of congenital anomalies in the children of female physicians who work in operating rooms.
4. Levels of anesthetic exposure are correlated with reproductive outcome. 6. B. The use of scavenging techniques lowers the environmental anesthetic levels in operating rooms. Review of existing epidemiologic studies suggests a slight increase in the relative risk of spontaneous abortion and congenital anomalies in the children of female physicians working in operating rooms. Although it is easy to quantify the levels of anesthetic in an operating room, it is harder to assess the effects of other factors such as stress, fatigue, and alterations in work schedule. Levels of anesthetic exposure have not correlated with reproductive outcome. (See page 58: Physical Hazards.) 7. Which of the following statements about methylmethacrylate is/are TRUE? 1. Reported risks from repeated occupational exposure to methyl methacrylate include skin irritation, allergic reactions, and asthma. 2. The Occupational Safety and Health Administration (OSHA) has established an 8-hour, time-weighted allowable exposure of 100 ppm of methylmethacrylate. 3. Airborne concentrations greater than 170 ppm have been associated with chronic lung, liver, and kidney damage. 4. When used properly, scavenging devices for venting methylmethacrylate vapor decrease the peak P environmental concentration of vapor by 75%. 7. E. When methyl methacrylate is prepared in the operating room to cement prostheses to bone, concentrations of up to 280 ppm have been measured. Scavenging devices for venting the vapor can decrease peak concentrations by 75%. OSHA has established an 8-hour, time-weighted average allowable exposure of 100 ppm. Airborne concentrations greater than 170 ppm have been associated with chronic lung, liver, and kidney damage. Reported risks from occupational exposure include allergic reactions and asthma, dermatitis, eye irritation, headache, and neurologic signs, which may occur at levels below the OSHA cutoffs. (See page 61: Physical Hazards: Methyl Methacrylate.)
8. Which of the following statements regarding latex allergy is/are TRUE? 1. The prevalence in anesthesia personnel is about 15%. 2. Sensitivity to latex can be reversed by avoiding latexcontaining compounds. 3. Type I immediate hypersensitivity reactions may manifest by a localized contact urticaria. 4. Type IV reaction (T-cell mediated) is the more severe allergic reaction seen with latex allergy. 8. B. Irritant or contact dermatitis accounts for the majority of reactions resulting from wearing latex-containing gloves. The prevalence of latex sensitivity among anesthesiologists is 15%. Type I immediate hypersensitivity reactions may manifest by a localized contact dermatitis or a generalized systemic response. True allergic reactions present as type IV (T-cell–mediated contact dermatitis) and the more severe type I (immunoglobulin E–mediated anaphylactic) reactions. Sensitivity cannot be reversed. (See page 62: Physical Hazards: Latex.) 9. Which of the following statements concerning influenza viruses is/are TRUE? 1. They are spread by coughing, sneezing, or talking via small particle aerosols. 2. Vaccination with inactivated virus confers immunity for life. 3. General anesthesia results in no increase of respiratory morbidity in asymptomatic patients infected with influenza virus. 4. Influenza virus vaccine contains two viral strains, type A and type B. 9. B. Influenza viruses are easily transmitted by small particle aerosols (sneezing, coughing, or talking). General anesthesia results in no increase in respiratory morbidity in asymptomatic patients infected with influenza virus. Antigenic variation of influenza viruses occurs over time, so new viral strains (usually two type A and one type B) are selected for inclusion in each year's vaccine. Because the virus has antigenic
variation from year to year, immunity is not for life. (See page 65: Infection Hazards.) 10. Which of the following forms of hepatitis primarily is/are transmitted by blood? 1. B 2. D 3. C 4. E 10. A. Hepatitis A is primarily transmitted by the fecal–oral route. Hepatitis B, C, and D are transmitted by blood. Hepatitis E is enterically transmitted. (See page 65: Infection Hazards.) 11. Which of the following form(s) of hepatitis can lead to a chronic carrier state? 1. C 2. D 3. B 4. A 11. A. Hepatitis B, C, and D can progress to chronic hepatitis and a chronic carrier state. (See page 65: Infection Hazards.) 12. Which of the following statements is/are TRUE? 1. Respiratory syncytial virus (RSV) can be recovered for up to 6 hours on contaminated environmental surfaces. 2. Severe acute respiratory syndrome (SARS) is spread by close person-to-person contact. 3. Transmission of cytomegalovirus (CMV) occurs through personto-person contact and contact with contaminated urine or blood. 4. Rubella infection can be associated with congenital malformations and fetal death if it is contracted during the first trimester of pregnancy.
12. E. RSV can be recovered for up to 6 hours on contaminated environmental surfaces. SARS is spread by close person-to-person contact, large respiratory droplets, and possibly airborne transmission. Transmission of CMV occurs through person-to-person contact and contact with contaminated urine or blood. Rubella infection may be associated with congenital malformations and fetal death if it is contracted during the first trimester of pregnancy. (See page 65: Infection Hazards.) 13. Which of the following statements concerning hepatitis B is/are TRUE? 1. Contaminated dry blood on an environmental surface may be infectious for more than 1 week. 2. Routine vaccination has reduced the risk of occupationally acquired hepatitis B virus (HBV) infection. 3. The presence of hepatitis B surface antigen (HbSa) in serum indicates active viral replication in hepatocytes. 4. The rate of transmission is significantly lower after mucosal contact with infected oral secretions than after percutaneous blood exposure. 13. E. HBV may be infectious for at least 1 week in dried blood on environmental surfaces. The rate of transmission is lower after mucosal contact with infected oral secretions than after percutaneous blood exposure. Routine vaccinations, use of safety devices, and postexposure prophylaxis have significantly reduced the risk of occupationally acquired HBV infection. The presence of HbSa in serum indicates active viral replication in hepatocytes and increases the risk of transmission. (See page 65: Infection Hazards.) 14. Which of the following has been documented as a means for transmission of the human immunodeficiency virus (HIV)? 1. Sexual contact 2. Blood 3. Perinatal transmission 4. Saliva and tears
14. A. HIV may be transmitted by sexual contact, exposure to contaminated blood, and perinatally. It can be found in saliva, tears, and urine, but these body fluids have not been implicated in viral transmission. (See page 65: Infection Hazards.) 15. Which of the following statements is/are TRUE? 1. The magnitude of radiation absorbed is a function of total exposure intensity, distance from the source of radiation, and the use of radiation shielding. 2. Radiation exposure is proportional to the square of the distance from the source. 3. Radiation exposure becomes minimal at a distance greater than 36 inches from the source. 4. Wearing a thyroid collar in addition to a lead apron protects virtually all vulnerable sites. 15. B. Radiation exposure is inversely proportional to the square of the distance from the source. Lead aprons and thyroid collars leave many vulnerable sites exposed, such as the long bones of the extremities, the cranium, the skin on the face, and the eyes. The magnitude of radiation absorbed by operating room personnel is a function of total exposure intensity, distance from the source of radiation, and the use of radiation shielding. Radiation exposure becomes minimal at a distance of greater than 36 inches from the source. (See page 62: Physical Hazards: Radiation.)
Chapter 4 Anesthetic Risk, Quality Improvement and Liability 1. All the following statements are true EXCEPT: A. The duty that the anesthesiologist owes the patient is to be a prudent and reasonable physician. B. Obtaining informed consent is a responsibility that all physicians have to their patients. C. Punitive damages are intended to punish the physician for negligence. D. Causation refers to the fact that a reasonably close causal relation exists between the anesthesiologist's acts and the resultant injury. E. General damages are actual damages that are a consequence of the injury, such as medical expenses. 1. E. In the most general terms, the duty that the anesthesiologist owes to the patient is to adhere to the “standard of care” for the patient's treatment. Because it is virtually impossible to delineate specific standards for all aspects of medical practice, the courts have created the concept of the “reasonable and prudent physician.” One of the general duties of the physician is obtaining informed consent for procedures. The requirement that the consent be “informed” is somewhat more opaque. The definition of causation is that a reasonably close causal relation exists between the anesthesiologist's acts and the resultant injury. Breach of duty is the failure of an anesthesiologist to fulfill his or her duty. The court will try to find that the anesthesiologist either did something that should not have been done or failed to do something that should have been done by a prudent and reasonable physician. General damages are those such as pain and suffering that directly result from the injury. Special damages are actual damages that are a consequence of the injury, such as medical expenses, loss of
income, and funeral expenses. Punitive damages are intended to punish the physician for negligence that was reckless, wanton, fraudulent or willful. (See page 88: Professional Liability.) 2. The court establishes “standard of care” through all of these EXCEPT: A. factual witness B. expert witness C. published societal guidelines D. textbooks E. written hospital policies 2. A. In the most general terms, the duty that the anesthesiologist owes to the patient is to adhere to the “standard of care” for the treatment of the patient. Because medical practice usually includes issues beyond the comprehension of lay jurors and judges, the court establishes a standard of care for a particular case by the testimony of “expert witnesses.” These witnesses differ from factual witnesses mainly in that they are allowed to give opinions. When a physician is called to court as the defendant in a malpractice suit, he or she becomes a factual witness. The standard of care may also be determined from published societal guidelines, written policies of a hospital or department, and textbooks and monographs. (See page 89: Standard of Care.) 3. Which of the following statements concerning risk management and quality improvement is TRUE? A. Quality improvement is broadly oriented toward reducing the liability exposure of the organization. B. Quality improvement is concerned with patient safety, but risk management is not. C. Risk management's exclusive goal is the reduction of institutional liability by maintenance and improvement of patient care. D. Risk management involves professional liability, contracts, employee safety, and public safety.
E. Quality improvement is concerned primarily with liability exposure of the institution. 3. D. Risk management and quality improvement programs work hand in hand to minimize liability and maximize quality of patient care. The two programs overlap their focus on patient safety. A hospital risk management program is broadly oriented toward reducing the liability exposure of the organization. This includes not only professional liability and therefore patient safety but also contracts, employee safety, public safety, and any other liability exposure of the institution. The main goals of quality improvement programs are the maintenance and improvement of the quality of patient care. (See page 84: Risk Management.) 4. All of the following statements concerning record keeping are true EXCEPT: A. Good records can form a strong defense in the face of malpractice litigation. B. Change of anesthetic personnel should be documented. C. The anesthesiologist's report of a catastrophic event need not be consistent with concurrent records because inconsistencies are easy to defend. D. A record-keeping error should be crossed out yet remain legible. E. Catastrophic events should be documented in narrative form in the patient's progress notes. 4. C. Good records can form a strong defense if they are adequate, and inadequate records can be disastrous. The anesthetic record itself should be accurate, complete, and as neat as possible. In addition to the patient's vital signs recorded every 5 minutes, special attention should be paid to ensure that the American Society of Anesthesiologists classification, monitors used, fluids administered, and doses and times of drugs given are accurately charted. All respiratory variables that are monitored should be documented. It is important to note when a change of anesthesia personnel occurs during the conduct of a case. If a critical incident occurs during the conduct of an anesthetic regimen, the anesthesiologist should document in narrative form in the patient's progress notes what happened, which drugs were used, what the time
sequence was, and who was present. A catastrophic intra-anesthetic event cannot be summarized adequately in a small amount of space on the usual anesthetic record. The report should be as consistent as possible with concurrent records such as those pertaining to the anesthetic, the operating room, the recovery room, and cardiac arrest. (See page 84: Risk Management in Anesthesia.) 5. The National Practitioner Data Bank (NPDB) requires input from all of the following EXCEPT: A. medical malpractice payment B. licensing actions by medical boards C. patient safety foundations D. clinical privilege actions by hospitals E. actions taken by the Drug Enforcement Agency (DEA) 5. C. The NPDB is a nationwide information system that theoretically allows licensing boards and hospitals a means of detecting adverse information about physicians. The NPDB requires input from five sources: medical malpractice payments, licensing actions by medical boards, clinical privilege actions by hospitals and professional societies, actions by the DEA, and Medicare and Medicaid exclusions. (See page 86: National Practitioner Data Bank.) 6. Which statement about continuous quality improvement (CQI) is FALSE? A. The focus of CQI is not on blame but rather on identification of the causes of undesirable outcomes. B. CQI continually tries to identify random errors and prevent them from recurring. C. CQI assumes that the operator is just one part of a complex system. D. After areas in need of improvement are identified by CQI programs, outcomes are measured and documented. E. CQI is instituted from the bottom up, not from the administrators down.
6. B. CQI takes a systems approach to identifying and improving quality. A CQI program may focus on undesirable outcomes as a way to identify opportunities for improvement in the structure and process of care. The focus is not on blame but rather on identification of the causes of undesirable outcomes. CQI assumes that the operator is just one part of a complex system. Random errors are inherently difficult to prevent, and programs focused in this direction are misguided. System errors, however, should be controllable, and strategies to minimize them should be within reach. After areas for improvement have been identified, their current status is measured and documented. If a change is identified that should lead to improvement, it is implemented. It is a process that is instituted from the bottom up by those who are actually involved in the process to be improved rather than from the top down by administrators. (See page 86: Quality Improvement and Patient Safety in Anesthesia.) 7. Pay for performance: A. is a program that pays physicians for the hours they work rather than for services B. is a program that provides money to hospitals that service Medicare and Medicaid patients C. is a program that provides monetary incentives for implementation of safe practices D. has been a part of quality improvement since its inception E. is a program that ranks doctors' abilities and pays them according to their rankings 7. C. A relatively recent development related to quality improvement is P4P, or “pay for performance.” P4P programs provide monetary incentives for implementation of safe practices, measuring performance, and achieving performance goals. This is a recent and evolving trend. (See page 88: Pay for Performance.) For questions 8 to 14, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct.
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8. For a malpractice suit against a physician to succeed, the patient/plaintiff must prove: 1. breach of duty 2. damages 3. causation 4. duty 8. E. “Malpractice” is a lay term that refers to professional negligence pursued in the legal system of civil laws. A successful malpractice suit must prove four things: (1) duty: that the anesthesiologist owed the patient a duty; (2) breach of duty: that the anesthesiologist failed to fulfill his or her duty; (3) causation: that a reasonably close causal relationship exists between the anesthesiologist's acts and the resultant injury; and (4) damages: that actual damage resulted because of a breach in the standard of care. (See page 88: The Tort System.) 9. Considering the cause of lawsuits against anesthesiologists, which of the following statements is/are TRUE? 1. The leading causes of death and brain damage injury are airway management problems. 2. Ulnar nerve injury often occurs despite apparently adequate positioning. 3. Anesthesia is a high-risk endeavor because of the use of complex equipment and potent drugs. 4. The leading injury for suits against anesthesiologists is brain damage. 9. A. The leading causes of lawsuits against anesthesiologists are death (22%), nerve damage (21%), and brain damage (10%). The causes of death and brain damage are predominantly problems with airway management. In the past, ulnar nerve injury was the most common cause of nerve damage claims, and it often occurs despite apparently adequate positioning. In the 1990s, spinal cord injury led the list. Anesthesia is a high-risk endeavor for many reasons. The anesthesiologist is likely to be the target of a lawsuit if an untoward outcome occurs
because the physician–patient relationship is usually tenuous at best. (See page 90: Causes of Anesthesia-Related Lawsuits.) 10. When a plaintiff's attorney files a complaint, the anesthesiologist should take certain actions, including which of the following? 1. Review the records but do not alter them. 2. Cooperate fully with the attorney provided by the insurer. 3. Make a detailed account of all events. 4. Discuss the case with all involved operating room personnel. 10. A. A lawsuit begins when the patient/plaintiff's attorney files a complaint. The anesthesiologist needs assistance in answering the complaint. Specific actions that should be taken at this point include the following: (1) do not discuss the case with anyone, including colleagues who may have been involved, operating personnel, or friends; (2) never alter any records; (3) gather all pertinent records, including copies of the anesthetic record, billing statements, and any correspondence concerning the case; (4) make notes recording all events recalled about the case; and (5) cooperate fully with the attorneys provided by the insurer. (See page 90: What to Do When Sued.) 11. If a physician is deposed by a plaintiff's attorney, the physician should do which of the following? 1. Never attempt to change his or her image by dressing conservatively. 2. Volunteer all information he or she has about the case. 3. Not spend too much time preparing so the responses do not seem to be rehearsed. 4. Rely on his or her attorney for assistance when preparing. 11. D. After a complaint has been filed, the malpractice suit moves on to the discovery phase. A deposition is the second mechanism of discovery. The plaintiff's attorney deposes the anesthesiologist, and the anesthesiologist must be constantly aware that what is said during the deposition carries as much weight as what is said in court. It is important to be factually prepared for the deposition. Review of notes, anesthetic records, and medical records is necessary. The physician
should dress conservatively and professionally. Information should never be volunteered. The physician should rely on his or her attorney for assistance when preparing for a deposition. (See page 90: What to Do When Sued.) 12. Concerning Jehovah's Witnesses and blood transfusions, which of the following statements is/are TRUE? 1. Physicians are obligated to treat all patients who apply for treatment, even if they refuse to have a blood transfusion. 2. Parents of a minor child may not legally prevent that child from receiving blood. 3. If a Jehovah's Witness consents to a blood transfusion, the physician needs to obtain a court order before giving the transfusion. 4. Some Jehovah's Witnesses will not accept an autotransfusion even if their blood remains in constant contact with their body via tubing. 12. C. The religious beliefs of Jehovah's Witnesses preclude them from receiving blood or blood products. Physicians are not obligated to treat all patients who apply for treatment. A physician has the right to refuse to care for a patient in an elective situation if the patient unacceptably limits the physician's ability to provide optimal care. Together, the physician and patient may decide to limit the physician's obligation to adhere to the patient's religious beliefs. Any agreement should be documented clearly in the medical record. It is true that some patients will not allow any blood that has left the body to be infused, but others will accept transfusion if the blood remains in constant contact with the body via tubing. Parents of a minor child may not legally prevent that child from receiving blood. (See page 85: Special Circumstances: “Do Not Attempt Resuscitation” and Jehovah's Witnesses.) 13. When considering the NPDB, which of the following statements is/are TRUE? 1. After a report is submitted to the NPDB, the physician may dispute the input.
2. Creation of the NPDB has allowed physicians to settle nuisance suits because their names are not added to the database. 3. A practitioner may query the NPDB about his or her file at any time. 4. The NPDB is a statewide information system. 13. B. The NPDB is a nationwide information system that theoretically allows licensing boards and hospitals a means of detecting adverse information about physicians. A practitioner may query the NPDB any time about his or her file. After a report has been submitted, the physician is notified and may dispute the input. The existence of the NPDB reporting requirements has made physicians reluctant to allow settlement of nuisance suits because doing so would cause their names to be added to the data bank. (See page 86: National Practitioner Data Bank.) 14. Considering quality improvement programs, which of the following statements is/are TRUE? 1. “Pay for performance” falls outside the domain of quality improvement. 2. Quality improvement outcome studies are easily applied to the field of anesthesia because it has a high rate of catastrophic outcomes. 3. Sentinel events are events with poor outcomes that are directly related to operator actions. 4. Critical incidents are events that cause or have the potential to cause patient injury if they are not noticed and corrected in a timely manner. 14. D. It is generally accepted that attention to quality will improve patient safety and satisfaction. Quality improvement programs are generally guided by requirements of The Joint Commission (formerly the Joint Commission on Accreditation of Healthcare Organizations [JCAHO]). However, adverse outcomes are relatively rare in anesthesia practices, making measurement of improvement difficult. To complement outcome measurements, anesthesia quality improvement programs may focus on critical incidents and sentinel events. Critical
incidents are events that cause or have the potential to cause patient injury if they are not noticed and corrected in a timely manner. Sentinel events are single, isolated events that may indicate a systematic problem. “Pay for performance” is an evolving trend in quality improvement programs. (See page 86: Quality Improvement and Patient Safety in Anesthesia.)
Chapter 5 Mechanisms of Anesthesia and Consciousness 1. For volatile anesthetics, potency is proportional to: A. Lipid solubility B. Vapor pressure C. Critical temperature D. Minimum alveolar concentration (MAC) E. None of the above 1. A. Anesthetic potency is proportional to lipid solubility. (See page 105: What Is the Chemical Nature of Anesthetic Target Sites?) 2. The Meyer-Overton rule: A. Correlates the potency of anesthetic gases with their solubility in oil B. Suggests the anesthetic target site to be hydrophilic in nature C. Is contradicted by the unitary theory of anesthesia D. Applies only to liquids E. Applies only to gases that never exist in the liquid state 2. A. The Meyer-Overton rule states that the potency of anesthetic gases is proportional to their lipid solubility. Because many different structurally unrelated anesthetics obey this rule, it has been speculated that all anesthetics act at the same molecular site. This concept is known as the unitary theory of anesthesia. The Meyer-Overton rule applies only to gases and volatile liquids
because an oil/gas partition coefficient cannot be determined for anesthetics in the liquid state. (See page 105: What Is the Chemical Nature of Anesthetic Target Sites? The Meyer-Overton Rule.) 3. In humans, the definition of minimum alveolar concentration (MAC) is: A. The alveolar partial pressure of a gas at which 50% of humans will not mount a sympathetic response B. The alveolar partial pressure of a gas at which 50% of humans will not respond to a surgical incision C. The alveolar partial pressure of a gas at which 30% of humans will not respond to a surgical incision D. The alveolar partial pressure of a gas at which 50% of subjects remain unresponsive to verbal stimuli E. The alveolar partial pressure of a gas at which 50% of subjects will follow a simple command 3. B. MAC is the alveolar partial pressure of a gas at which 50% of subjects will respond to a surgical incision. The use of end-tidal gas concentration provides an index of the “free” concentration of anesthetic gas required to produce anesthesia. (See page 97: How Is Anesthesia Measured?) For questions 4 to 7, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 4. General anesthesia results from interruption of nervous system activity at which of the following levels? 1. Cerebral cortex 2. Spinal cord 3. Brainstem 4. Peripheral sensory receptors
4. A. Anesthetics are able to produce effects on a variety of anatomic structures in the central nervous system, including the cerebral cortex, brainstem, and spinal cord. Anesthetics clearly alter cortical electrical activity, as evidenced by the consistent changes (increased latency, decreased amplitude) in surface electroencephalographic patterns recorded during anesthesia. A role for the brainstem in anesthetic action is supported by studies examining somatosensory evoked potentials. The actions of volatile anesthetics in the spinal cord are mediated, at least in part, by direct effects on the excitability of spinal motor neurons. This is supported by several electrophysiologic studies showing inhibition of excitatory synaptic transmission in the spinal cord. Animal studies have shown that volatile anesthetics have no significant effects on peripheral sensory receptors. (See page 99: Where in the Central Nervous System Do Anesthetics Work? Synaptic Function.) 5. Which of the following statements is/are TRUE? 1. γ -Aminobutyric acid (GABA) is an excitatory neurotransmitter. 2. Volatile anesthetics modulate GABA receptor function. 3. Benzodiazepines have no effect on GABA receptors. 4. Barbiturates and etomidate act at GABA receptors. 5. C. GABA receptors mediate the postsynaptic response to synaptically released GABA, an important inhibitory neurotransmitter. Barbiturates, benzodiazepines, propofol, etomidate, and volatile anesthetics all have been shown to modulate GABA receptor function. (See page 102: Anesthetic Effects on Ligand-Gated Ion Channels: GABA-Activated Ion Channels.) 6. General anesthetics have been shown to inhibit excitatory synaptic transmission in the: 1. Sympathetic ganglia
2. Olfactory cortex 3. Hippocampus 4. Spinal cord 6. E. General anesthetics have been shown to inhibit excitatory synaptic transmission in the sympathetic ganglia, olfactory cortex, hippocampus, and spinal cord. (See page 99: How Do Anesthetics Interfere with the Electrophysiologic Function of the Nervous System? Synaptic Function.) 7. Important features of minimum alveolar concentration (MAC) include: 1. MAC represents the average response of a whole population of subjects rather than the response of a single subject. 2. MAC can only be directly applied to anesthetic gases. 3. MAC does not reflect the end-tidal concentration at which there is loss of response to verbal stimuli. 4. The MAC endpoint in a MAC determination is relative rather than quantal. 7. A. The MAC concept has several important limitations, particularly when trying to relate MAC values to anesthetic potency observed in vitro. First, the endpoint in a MAC determination is quantal: A subject is either anesthetized or unanesthetized; he or she cannot be partially anesthetized. Furthermore, MAC represents the average response of a whole population of subjects rather than the response of a single subject. Another limitation of MAC measurements is that they can only be directly applied to anesthetic gases. Parenteral anesthetics (barbiturates, neurosteroids, propofol) cannot be assigned a MAC value, making it difficult to compare the potency of parenteral and volatile anesthetics. A further limitation of MAC is that it is highly dependent on the anesthetic endpoint used to define it. For example, if loss of response to verbal commands is used as an
anesthetic endpoint, the MAC values obtained (MACawake) will be much lower than classic MAC values based on response to a noxious stimulus. (See page 97: How Is Anesthesia Measured?)
Chapter 6 Genomic Basis of Perioperative Medicine Match the following genetic terms with the appropriate definitions: 1. Mutation A. DNA sequence alternatives B. Insertion or deletion of one or more nucleotides C. Nucleotide polymorphisms inherited in blocks D. Rare genetic variants E. Widespread DNA sequence variations 1. D. 2. Polymorphism A. DNA sequence alternatives B. Insertion or deletion of one or more nucleotides C. Nucleotide polymorphisms inherited in blocks D. Rare genetic variants E. Widespread DNA sequence variations 2. E. 3. Indels A. DNA sequence alternatives B. Insertion or deletion of one or more nucleotides C. Nucleotide polymorphisms inherited in blocks D. Rare genetic variants E. Widespread DNA sequence variations 3. B.
4. Haplotypes A. DNA sequence alternatives B. Insertion or deletion of one or more nucleotides C. Nucleotide polymorphisms inherited in blocks D. Rare genetic variants E. Widespread DNA sequence variations 4. C. 5. Allele A. DNA sequence alternatives B. Insertion or deletion of one or more nucleotides C. Nucleotide polymorphisms inherited in blocks D. Rare genetic variants E. Widespread DNA sequence variations 5. A. Perioperative genomics applies functional genomics into clinical practice. Physicians need to understand the patterns of human genome variation and its methods of study. Mutations are rare genetic variations that have been identified with more than 1500 disorders. Polymorphism refers to widespread population-based DNA variations. Indels are insertions and deletions of nucleotides. Single nucleotide polymorphisms inherited in blocks are referred to as haplotypes. Alleles are DNA sequence alternatives that contribute to either mutant variants or polymorphism within a population. (See page 116: Overview of Human Genetic Variation.) 6. The term used to refer to nearby single nucleotide polymorphisms on a chromosome that are inherited in blocks is: A. alleles B. haplotypes C. polymorphic mutations D. indels E. phenotype
6. B. Haplotypes are inherited in blocks, and an analysis of these can be useful in discovering diseased genes. An indel is an insertion or deletion of one or more nucleotides. (See page 116: Overview of Human Genetic Variation.) 7. One of the most common inherited prothrombotic risk factors is a point mutation in which factor? A. Factor II B. Factor V C. Factor VII D. Factor XI E. Factor XII 7. B. A point mutation in coagulation factor V results in resistance to activated protein C and is commonly known as factor V Leiden. This factor has been associated with thromboses in the postoperative setting. (See page 123: Coagulation Variability and Perioperative Myocardial Outcomes.) 8. After cardiac surgery, what is the incidence of significant neurologic morbidity (ranging from focal stroke to coma)? A. 0.1%–0.2% B. 1%–3% C. 10%–15% D. 20%–30% E. >40% 8. B. The incidence of coma and focal stroke after cardiac surgery is approximately 1% to 3%. More subtle deficits occur in up to 69% of patients. This variability in neurologic deficit is poorly explained by risk factors related to the procedure. The role of apolipoprotein E genotypes in relation to modulating the inflammatory response, extent of aortic atheroma, and cerebral blood flow and autoregulation may explain the observed associations with poor neurologic outcomes. (See page 124: Genetic Susceptibility to Adverse Perioperative Neurologic Outcomes.)
9. Malignant hyperthermia follows what pattern of inheritance? A. Autosomal dominant B. Autosomal recessive C. X-linked dominant D. X-linked recessive E. It is not an inherited disease. 9. A. Malignant hyperthermia is a rare autosomal dominant genetic disease of skeletal muscle calcium metabolism. Susceptibility to malignant hyperthermia has been linked to the ryanodine receptor gene locus on chromosome 19. (See page 127: Genetics of Malignant Hyperthermia.) 10. In classical genetics, what is meant by “wild-type” individual? A. An individual with individual gene mutations B. An individual with traits controlled by multiple genes C. An individual with genes acutely affected by the environment D. An individual with nonmutant individual genes E. Your uncontrollable 3-year-old nephew 10. D. In classical genetics, single gene traits were identified and studied. Phenotypic differences attributed to individual genes were observed, and the genes were isolated. The nonmutant or original phenotype expressed by a single gene was termed “wild type” and was compared with the new phenotypes or “mutants.” (See page 127: Genetic Variability and Response to Anesthetic Agents.) 11. What is a “knockout” animal? A. An animal that misexpresses an additional gene B. An animal that overexpresses an additional gene C. A kangaroo with boxing gloves D. An animal with a nonfunctional gene E. An animal with a gene predisposing to sleep
11. D. “Knockout” animals are created by inserting a vector with a disrupted gene into an animal. Typically, a mouse is used. The goal is to achieve two nonfunctioning alleles so that a gene is not expressed. This is done to study specific functions of specific genes. Animals that misexpress or overexpress a gene are termed “transgenic.” (See page 127: Genetic Variability and Response to Anesthetic Agents.) 12. Our understanding of pain has been increased by mice with knockout genes for: A. Substance P B. Opioid transmitters C. Nerve growth factors D. All of the above E. None of the above 12. D. Multiple genes appear to mediate sensitivity to noxious stimuli and chronically painful exposure. Various knockout mice missing functional genes for neurotrophins, nerve growth factors, substance P, opioid transmitters, and nonopioid transmitters and their receptors have significantly contributed to our knowledge of pain processing. (See page 127: Genetic Variability and Response to Anesthetic Agents.) 13. Numerous clinical trials attempting to block single inflammatory mediators in patients with sepsis have been largely unsuccessful. Which of the following best explains the lack of success? A. Large tertiary care centers have a low incidence of septic shock. B. There is a lack of clinical investigators with an interest in septic shock. C. Septic shock is unimportant as a disease syndrome. D. Cascades of biologic pathways that interact in complex and redundant ways are triggered by stressful stimuli. E. Sepsis has a negligible worldwide economic impact and thus receives a small percentage of funds for investigation.
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13. D. At the cell level, various cascades and pathways are triggered when an organism is stressed. These pathways are often interrelated and work to both increase and suppress gene expression. Because negative and positive feedback occur in a complex manner, attempts to study the expression of a single gene (products such as tumor necrosis factor-α) have been difficult. (See page 130: Functional Genomics of Injury.)
Chapter 7 Pharmacologic Principles 1. Which of the following statements concerning passage of drugs across membranes is FALSE? A. Small lipophilic drugs can passively diffuse across cell membranes. B. The walls of most capillaries do not allow passage of watersoluble drugs. C. Active transport is able to shuttle proteins against their concentration gradient. D. Thiopental easily crosses cell membranes. E. The capillaries of the central nervous system (CNS) do not allow passive transport of water-soluble drugs. 1. B. The large spaces between capillaries allow for passage of watersoluble drugs, except in the brain, where there are tight interendothelial cell junctions (the so-called blood–brain barrier). Transcellular penetration is much easier for small, lipid-soluble drugs, which can more readily cross lipid membranes. This accounts for the greater CNS penetrability of thiopental. Distribution of highly polar drugs, such as neuromuscular blockers, is essentially limited to the extracellular fluid. (See page 138: Pharmacokinetic Principles Absorption and Routes of Administration.) 2. Which of the following statements about drug distribution to the central nervous system (CNS) is FALSE? A. Equilibration in the brain and muscle does not occur simultaneously. B. Diffusion of water-soluble drugs into the brain is severely restricted. C. For more polar compounds, the rate of entry into the brain is proportional to their lipid solubility.
D. Distribution of highly lipid-soluble drugs into the CNS is directly proportional to cerebral blood flow. E. Recovery from a single dose of thiopental depends primarily on hepatic elimination. 2. E. Recovery from thiopental largely depends on redistribution from the brain to other tissues (e.g., muscle); the effects of elimination are not noted until later in the course of recovery and are relatively minor unless large doses are used. The distribution of lipid-soluble drugs into the CNS is very rapid and thus is directly proportional to cerebral blood flow (i.e., to the amount of drug that is delivered to the brain). Polar compounds do not pass into the brain readily because brain capillaries do not have the large aqueous channels typical of capillaries in other tissues. For more polar compounds, the rate of entry into the brain is proportional to the lipid solubility of the nonionized drug. (See page 139: Drug Distribution.) 3. How many minutes after an intravenous injection does the brain concentration of propofol peak? A. 1 B. 4 C. 6 D. 8 E. 11 3. A. The brain concentration of propofol peaks within 1 minute because of high blood flow to the brain and the high lipid solubility of propofol. Propofol quickly diffuses back into the blood, where it is redistributed to other tissues that are still taking up drug. Its duration of action is thus very short unless high doses are used and termination of drug action becomes dependent on drug elimination. (See page 140: Drug Distribution: Redistribution.) 4. Elimination half-life A. is not influenced by drug distribution B. is not influenced by drug elimination
C. is the time it takes the amount of drug in the vessel-rich group to decrease by 50% D. is not influenced by age E. is the time it takes the amount of drug in the body to decrease by 50% 4. E. The elimination half-life of a drug is the time it takes the amount of drug in the body to decrease by 50%. It is influenced by the volume of distribution for the drug and the rate of elimination of the drug. The rate of elimination is dependent on the age of the patient taking the drug. (See page 146: Elimination Half-Life.) 5. Which statement about drug elimination is FALSE? A. Elimination can occur by excretion of unchanged drug. B. Metabolism is a step in some drug elimination. C. The liver and kidney are the most important organs in drug elimination. D. The liver eliminates drugs primarily by excretion. E. The kidney primarily excretes water-soluble, polar compounds. 5. D. Elimination is an inclusive term that refers to all the processes that remove drugs from the body. Elimination occurs either by excretion of unchanged drug or by metabolism (biotransformation) and subsequent excretion of metabolites. The liver and kidneys are the most important organs for drug elimination. The liver eliminates drugs primarily by metabolism to less active compounds and, to a lesser extent, by hepatobiliary excretion of drugs or their metabolites. The primary role of the kidneys is the excretion of water-soluble, polar compounds. (See page 140: Drug Elimination.) 6. Which of the following indicates the units for elimination clearance (drug clearance)? A. mL/min B. mL/kg/min C. %/kg D. mL/kg
E. kg/% 6. A. Elimination clearance has units of flow (e.g., mL/ min). It is the portion of the volume of distribution (the theoretical volume of a drug) from which the drug is completely removed in a given time interval. (See page 140: Drug Elimination.) 7. Which of the following statements concerning the volume of drug distribution and clearance is TRUE? A. The smaller the volume of distribution, the longer the halftime of elimination. B. The calculated volume of steady-state distribution can exceed the actual volume of the body. C. The volume of distribution is equal to the total amount of drug present divided by plasma volume and vessel-rich group volume. D. The volume of distribution provides information regarding the tissues into which the drug distributes and the concentration in those tissues. E. The volume of distribution cannot be as small as the plasma volume. 7. B. Extensive tissue uptake of a drug is reflected by a large volume of the peripheral compartment. If there is binding to the tissues, then the calculated volume of distribution may exceed the actual volume of the body. It may be as small as the plasma volume. The volume of distribution is equal to the total amount of drug divided by the concentration. The volume of distribution does not provide any information regarding the tissues into which the drug distributes or the concentrations in those tissues. (See page 145: Volume of Distribution.) 8. If 10 mg of drug is present and the plasma concentration is 2 mg/L, P then the volume of distribution (Vd) is ___________ L. A. 5 B. 50 C. 500 D. 20
E. 0.2 8. A. The Vd is 5 L. Vd = Total amount of drug/ Concentration. (See page 146: Volume of Distribution: One-Compartment Model.) 9. Which statement regarding renal function is FALSE? A. Drug doses must be altered in patients with decreased renal function. B. Low cardiac output states decrease renal function. C. Acute renal failure requires a change in drug doses. D. Patients compensate for chronic renal failure, so drug doses should not be changed in these patients. E. Age decreases renal function. 9. D. Renal drug clearance, even for drugs eliminated primarily by tubular secretion, is dependent on renal function. Therefore, in patients with acute and chronic causes of decreased renal function, including age, low cardiac output states, and hepatorenal syndrome, drug dosing must be altered to avoid accumulation of parent compounds and potentially toxic metabolites. (See page 142: Renal Drug Clearance.) 10. Which form of biotransformation is particularly prominent when intracellular oxygen tension is very low? A. Reduction B. Oxidation C. Hydrolysis D. Hydroxylation E. Dealkylation 10. A. Reductive biotransformation (i.e., transfer of electrons to the drug molecule) is inhibited by oxygen. Thus, it is facilitated when intracellular oxygen tension is low. (See page 140: Phase I Reactions.) 11. Which of the following statements concerning hepatic clearance is FALSE?
A. If the extraction ratio (and intrinsic clearance) is very high, then total hepatic clearance will be proportional to hepatic blood flow. B. Clearance of drugs with low extraction ratios occurs relatively independently of the amount of hepatic blood flow. C. Intrinsic clearance is the amount of blood that bypasses the liver, not allowing for drug clearance. D. The hepatic extraction ratio is the fraction of the drug removed from the blood passing through the liver. E. Clearance of lidocaine is reduced in patients with congestive cardiac failure in proportion to the decrease in hepatic blood flow. 11. C. Hepatic extraction ratio is the fraction of the drug removed from the blood passing through the liver. Intrinsic clearance is the intrinsic ability of the liver to metabolize the drug. When the intrinsic clearance is low, clearance occurs essentially independently of hepatic blood flow. A very high liver extraction ratio indicates that the liver is removing most of the drug that is passing through it. Until the liver's capacity is exceeded, drug removal increases as the blood flow increases. A decrease in liver perfusion, as may occur with congestive heart failure, decreases the clearance of drugs that are highly extracted (e.g., lidocaine). (See page 142: Hepatic Drug Clearance.) 12. Each of the following has a high hepatic extraction ratio EXCEPT: A. Rocuronium B. Lidocaine C. Metoprolol D. Propofol E. Meperidine 12. A. The extraction ratios for lidocaine, meperidine, propofol, and metoprolol are very high; the extraction ratio for rocuronium is much lower. (See page 144: Table 7-3: Classification of Drugs Encountered in Anesthesiology According to Hepatic Extraction Ratios.)
13. Which of the following statements concerning renal clearance is FALSE? A. Normally, only unbound drugs can pass through the glomerular membrane into the renal tubule. B. Active transport makes renal elimination more efficient. C. Highly lipophilic drugs, such as thiopental, undergo virtually no renal clearance of the parent molecule. D. Changes in renal drug clearance are proportional to changes in creatinine clearance. E. Passive elimination of drugs by glomerular filtration is very efficient. 13. E. All unbound drug is filtered by the glomerulus, with a glomerular filtration rate that is 20% of renal plasma flow. Passive elimination of drugs by glomerular filtration is inefficient. Active transport makes renal elimination more efficient. Lipid-soluble drugs undergo reuptake in the renal tubule and have virtually no renal clearance. Renal clearance is directly proportional to renal blood flow and hence creatinine clearance. (See page 142: Renal Drug Clearance.) 14. Which of the following statements about pharmacokinetics is FALSE? A. In first-order kinetics, when the concentration is high, it will decrease faster than when it is low. B. The brain, heart, lungs, and muscle make up the vessel-rich group. C. A first-order kinetic process is one in which a constant fraction of the drug is removed during a finite period of time. D. Awakening after a single dose of thiopental is primarily the result of redistribution. E. The disadvantage of perfusion-based pharmacokinetic models is their complexity. 14. B. The term pharmacokinetics refers to the quantitative analysis of the relationship between the dose of a drug and the ensuing changes in drug concentration in the blood and other tissues. Physiologic
pharmacokinetic models provide much insight into factors that affect drug action. In these models, body tissues are classified according to similarities in perfusion and affinity for drugs. Highly perfused tissues, including the brain, heart, lungs, liver, and kidneys, make up the vesselrich group. Muscle and skin comprise the lean tissue group, and fat is considered a separate group. These models have established that awakening after a single dose of thiopental is primarily the result of redistribution from the brain to the muscles and skin. The disadvantage of perfusion-based models is their complexity. The disposition of most drugs follows first-order kinetics. A first-order kinetic process is one in which a constant fraction of the drug is removed during a finite period of time. Because a constant fraction is removed per unit of time in firstorder kinetics, the absolute amount of drug removed is proportional to the concentration of the drug. When the concentration is high, it decreases faster than when it is low. (See page 144: Pharmacokinetic Models.) 15. What is the half-time of elimination for a drug that undergoes first-order elimination with a rate constant of 0.1 minute? A. 10 minutes B. 100 minutes C. 0.1 minutes D. 6.93 minutes E. 693 minutes 15. D. Half-life (minutes) = Natural log of 2 ÷ Given drug's rate constant of elimination = 0.693 ÷ 0.1 minute = 6.93 minutes. Thus, it would take 6.93 minutes for the concentration to change by a factor of 2 for a drug with a rate constant of 0.1 minute. (See page 144: Rate Constants and Half-Lives.) 16. How many minutes are required for approximately 97% elimination of a drug undergoing first-order elimination with a halftime of 10 minutes? A. 10 B. 30
C. 50 D. 70 E. 100 16. C. When a drug is eliminated by first-order elimination, its concentration is generally reduced by 97% after five half-times of elimination. Conversely, if a drug is infused at a constant rate, the concentration approaches a steady state after approximately five halflives. (See page 144: Rate Constants and Half-Lives.) 17. What is mean residence time (MRT)? A. The time it takes a drug to reach its steady state after starting an infusion B. The time a drug molecule spends in the vessel-rich group of tissues C. The average time a drug molecule spends in the body before being eliminated D. The average time a drug molecule spends in the renal cells before being excreted E. The average time it takes a drug to reach its volume of distribution 17. C. MRT is the average time a drug molecule spends in the body before being eliminated. It is the main unique parameter of noncompartmental analysis, which attempts to avoid the experimental requirements of a physiologic model when describing pharmacokinetics. (See page 149: Noncompartmental [Stochastic] Pharmacokinetic Models.) 18. Which statement regarding target-controlled infusions (TCI) is TRUE? A. They have been commercially available for more than 30 years. B. They require the physician to calculate the volume of distribution for each drug and patient. P P P
C. All studies have shown that TCI improves times to emergence. D. TCI is important intraoperatively but can not be used for postoperative pain management. E. The physician must program a target plasma concentration of the drug into the pump. 18. E. TCI is a method of drug delivery that links a computer with the appropriate pharmacokinetic model to an infusion pump. It allows physicians to enter the desired target plasma concentration of a drug, and the computer instantaneously calculates the appropriate infusion scheme to achieve this target. TCI was first described in the early 1980s and became commercially available in the late 1990s. Although the pharmacologic principle of relating a concentration rather than a dose is scientifically sound, few studies have actually attempted to determine whether TCI improves clinical performance or outcome. Only a few limited studies have actually compared manual infusion control with TCI. Some have shown better control and a more predictable emergence with TCI, but others have simply shown no advantage. TCI has been used to provide postoperative analgesia with alfentanil. (See page 157: Target-Controlled Infusions.) For questions 19 to 22, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 19. Individual variation in drug metabolism can be caused by: 1. Genetic differences of metabolic enzymes 2. Age 3. Exposure to other drugs 4. Gender 19. A. Rates of drug metabolism vary between individuals based on age, differences in metabolic enzymes, and exposure to xenobiotics. Gender does not seem to play a role in the rate of drug metabolism. (See page 140: Drug Elimination.) 20. Which of the following have significant renal excretion? 1. Pancuronium
2. Rocuronium 3. Nor-meperidine 4. Thiopental 20. A. Many drugs, including pancuronium and rocuronium, are excreted by the kidneys. Others have pharmacologically active metabolites that are renally excreted, including meperidine's metabolite nor-meperidine. (See page 142: Table 7-2: Drugs with Significant Renal Excretion.) 21. TRUE statements about agonists and antagonists include: 1. Competitive antagonists bind irreversibly to receptors. 2. Competitive antagonists do not change the maximum possible effect that can be elicited by an agonist. 3. Noncompetitive antagonists bind reversibly to receptors. 4. Noncompetitive antagonists change the maximum effect elicited by an agonist. 21. D. Competitive antagonists bind reversibly to receptors, and their blocking effect can be overcome by high concentrations of an agonist. Therefore, competitive antagonists produce a parallel shift in the dose– response curve, but the maximum effect is not altered. Noncompetitive antagonists bind irreversibly to receptors. This has the same effect as reducing the number of receptors and shifts the dose–response curve downward and to the right, decreasing both the slope and the maximum effect. (See page 150: Drug-Receptor Interactions: Agonists, Partial Agonists, and Antagonists.) 22. TRUE statements regarding drug infusions of propofol include: 1. A multicompartment model must be used to predict propofol concentration during an infusion. 2. The concentration of infused propofol reaches 90% of the steady state in 3.3 half-lives. 3. Propofol's elimination half-life is 6 hours. 4. It takes 6 hours from the start of a propofol infusion to reach 50% of its steady-state concentration.
22. B. In a one-compartment model, the rise of drug concentration during a constant infusion is the mirror image of its elimination profile. Using a single-compartment model, drug infusions reach 90% of their steady state in 3.3 half-lives. Propofol, however, partitions extensively to pharmacologically inert body tissues, so a multicompartment model must be used to predict its concentrations during infusions. The half-life of propofol is 6 hours, yet the multicompartment model of drug concentration predicts that it will reach 50% of steady state in less than 30 minutes from starting a constant infusion. (See page 153: Rise to Steady-State Concentration.)
Chapter 8 Electrical and Fire Safety For questions 1 to 8, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 1. Electrical contact may produce which of the following types of injuries? 1. Disruption of normal electrical function of the cells 2. Respiratory paralysis 3. Muscle contraction 4. Cardiac arrhythmias 1. E. Electrical contact may result in flow of current through an individual. First, the electrical current may disrupt the normal electrical function of cells. Depending on the magnitude, it can cause muscle contraction, changes in brain function, respiratory paralysis, and disruption of normal heart function leading to ventricular fibrillation. Depending on the path taken, the flow of current through tissue will produce heat if the resistance to flow is high. (See page 167: Source of Shocks.) 2. Injury from macroshock is affected by which of the following? 1. Skin resistance 2. Duration of contact with the electrical source 3. Current density 4. Capacitance 2. A. Injury from electricity is influenced by skin resistance, duration of contact with the electrical source, and current density.
High skin resistance decreases the transfer of electricity and thus is protective. Contact time results in more current flow and thus more energy transferred, which produces more tissue damage in high-resistance tissues. Furthermore, prolonging the exposure to current flow increases the risk of inducing ventricular fibrillation during a vulnerable period of the cardiac cycle. Current density describes the surface area onto which the current is transferred. The quantity of injury is inversely related to the surface area and is directly related to the quantity of current transferred through that surface area. This is the reason that small voltages applied to a small surface area of a vulnerable tissue result in injury (e.g., ventricular fibrillation with current down a pacing wire). Capacitance refers to the storage of current in two conductive materials separated by an insulatory layer. It does not play a role in the magnitude of injury, although capacitance can store current, which can result in injury even when an item is unplugged. (See page 166: Capacitance and page 167: Source of Shocks.) 3. Which of the following statements regarding grounded electrical systems is/are TRUE? 1. The hot wire (black) carries a voltage of 120 V above ground. 2. A ground wire (green or bare) is necessary to complete a circuit. 3. The white wire is neutral. 4. The circuit breaker prevents macroshock by preventing current flow. 3. B. In a normal grounded circuit, the power company delivers a hot wire with a voltage above ground. Within a house, it is carried by a black wire. The power company also supplies a neutral wire for the current to return to the earth. This is usually a white wire. These two wires are all that are needed to produce the path for the current to flow through a resistance and perform work. A circuit breaker between the hot supply and the receptacle
prevents current flow in excess of the wire's capabilities. Exceeding the wire's capabilities results in heat production and a possible fire hazard. Circuit breakers do not prevent macroshock. The ground wire, which is bare or green, acts as a safety feature to prevent shock in the event that the object containing the electricity comes in contact with the hot wire. In these malfunctioning devices, the casing of the object becomes hot and carries the same potential as the hot wire. If someone comes into contact with the case (and if he or she is grounded), he or she will provide a path for current to flow and will be electrocuted. The ground wire acts as a lowresistance pathway for electrical potentials within the case and thus reduces the flow in the individual. A ground wire is a safety feature but is not necessary to complete a circuit. (See page 169: Electrical Power: Grounded.) 4. An ungrounded electrical system has which of the following properties? 1. It makes the use of a ground wire obsolete. 2. The 120-V potential exists only between the two wires in the system. 3. It eliminates the potential for microshock. 4. It requires the presence of an isolation transformer. 4. C. An ungrounded power supply uses an isolation transformer to separate itself from the power company. The isolation transformer creates a power gradient of 120 V between the two wires within the system but no gradient between any of the two wires and the ground. Thus, individuals can contact either wire of an ungrounded system and not complete a circuit. An individual who contacts both wires within the isolated system will complete a circuit and be electrocuted. Isolation transformer systems thus significantly reduce the risk of macroshock in the operating room environment but do not reduce the risk of microshock. The use of a ground wire is still used within an isolation transformer system because it constitutes an additional, alternative safety system. The ground
wire is attached to the device's case to provide a low-resistance pathway if the case of the device becomes electrically hot. (See page 173: Electrical Power: Ungrounded.) 5. Which of the following statements regarding the line isolation monitor (LIM) is/are TRUE? 1. The LIM measures the impedance of current flow to ground that exists in the system. 2. The LIM is set to alarm at 2 to 5 mA. 3. The LIM is necessary to identify faulty equipment, which, despite a contact to ground, will function normally in an ungrounded system. 4. The value on the LIM display indicates that current is actively flowing to ground. 5. A. The LIM is a device that monitors the integrity of the isolation of the ungrounded electrical system. Such monitoring is essential in that a first fault to the ground in an isolated system will result in normal function of an electrical device (but will alert that the isolation of the power has been breached). The typical cause of loss of isolation is that the case and the ground wire have become connected. Because the ground is not in the path of the isolated power, no short circuit exists, and the equipment is safe to use and will continue to function. However, if an individual comes into contact with the other limb of the isolated circuit, he or she would then be in contact with both sides of the isolated power (through the ground and the ground wire) and will thus receive a shock. The LIM monitors the impedance to ground of each side of the isolated power. The value measured on the LIM does not mean that current is actually flowing; rather, it indicates how much current would flow in the event of a fault. Normally, the LIM is set to alarm at 2 to 5 mA. In a perfect system, the impedance to ground is infinite, but because alternating current creates capacitance (and this can leak to the ground even with perfect isolation), a buffer of
acceptable leak is permitted to prevent alarming secondary to capacitance leakage. (See page 175: The Line Isolation Monitor.) 6. Which of the following statements regarding fires in the operating room is/are TRUE? 1. Fires in the operating room present much less danger compared with 100 years ago, when patients were anesthetized with flammable anesthetic agents. 2. A combination of 50% oxygen and 50% nitrous oxide would support combustion as well as 100% oxygen. 3. An ignition source and an oxidizer are enough to start a fire. 4. Paper drapes are much easier to ignite and can burn with greater intensity than cloth drapes. 6. C. Fires in the operating room are just as much a danger today as they were 100 years ago, when patients were anesthetized with flammable anesthetic agents. Today, the risk of an operating room fire is probably as great as or greater than in the days when ether and cyclopropane were used. This is because of the routine use of potential sources of ignition in an environment rich in flammable materials. For a fire to start, three elements are necessary: a heat or ignition source, fuel, and an oxidizer. The main oxidizers in the operating room are air, oxygen, and nitrous oxide. Oxygen and nitrous oxide function equally well as oxidizers, so a combination of 50% oxygen and 50% nitrous oxide would support combustion as well as 100% oxygen. Fuel for a fire can be found everywhere in the operating room. Paper drapes have largely replaced cloth drapes, and these are much easier to ignite and can burn with greater intensity. Other sources of fuel include gauze dressings, endotracheal tubes, gel mattress pads, and even facial or body hair. (See page 185: Fire Safety.) 7. Regarding fires in the operating room, which of the following is/are TRUE?
1. Major ignition sources for operating room fires are the electrosurgical unit and the laser. 2. The ends of some fiberoptic light cords can become hot enough to start a fire. 3. Fires on a patient occur most often during surgery in and around the head and neck, where the patient is receiving monitored anesthesia care. 4. Fires in or on the patient represent an unlikely but possible type of operating room fire. 7. A. Major ignition sources for operating room fires are electrosurgical units and lasers. However, the ends of some fiberoptic light cords can also become hot enough to start a fire if they are placed on paper drapes. Operating room fires can be divided into two different types. The more common type of fire occurs in or on the patient. These include endotracheal tube fires; fires during laparoscopy or bronchoscopy; or a fire in the oropharynx, which may occur during a tonsillectomy. The other type of operating room fire is one that is remote from the patient, including an electrical fire in a piece of equipment. Fires on the patient seem to have become the most frequent type of operating room fire. These cases most often occur during surgery in and around the head and neck, where the patient is receiving monitored anesthesia care and supplemental oxygen is being administered by either a face mask or a nasal cannula. (See page 185: Fire Safety.) 8. Regarding the response to an operating room fire, which is/are TRUE? 1. The operating room sprinkler systems effectively respond to the majority of fires. 2. If an endotracheal tube is on fire, it should be removed immediately and then extinguished.
3. If the paper drapes are burning, water or saline will likely douse the fire effectively. 4. Common acronyms for responding to a fire include “RACE” and “PASS.” 8. D. If a fire does occur, it is important to extinguish it as soon as possible. This is best accomplished by removing the oxidizer from the fire. Therefore, if an endotracheal tube is on fire, disconnecting the anesthetic circuit from the tube or disconnecting the inspiratory limb of the circuit will usually put out the fire immediately. It is not recommended to remove a burning endotracheal tube because this may cause even greater harm to the patient. After the fire has been extinguished, the endotracheal tube can be safely removed, the airway inspected via bronchoscopy, and the patient's trachea reintubated. If the drapes are burning, particularly if they are paper drapes, they must be removed and placed on the floor. Paper drapes are impervious to water, so throwing water or saline on them will do little to extinguish the fire. After the burning drapes have been removed from the patient, the fire can then be extinguished with a fire extinguisher. In most operating room fires, the sprinkler system is not activated. This is because sprinklers are usually not located directly over the operating room table, and operating room fires are seldom hot enough to activate the sprinklers. To use a fire extinguisher effectively, the acronym “PASS” can be helpful. This stands for pull the pin to activate the fire extinguisher, aim at the base of the fire, squeeze the trigger, and sweep the extinguisher back and forth across the base of the fire. When responding to a fire, the acronym RACE is useful. This stands for rescue, alarm, confine, and extinguish. (See page 185: Fire Safety.)
Chapter 9 Experimental Design and Statistics 1. If a target population contains several strata of importance, the best method of obtaining a representative population sample is: A. Limit sampling B. Convenience sampling C. Crossover sampling D. Random sampling E. Double-blind sampling 1. D. A sample is a subset of the target population. The best hope for a representative sample of the population would be realized if every subject in the population had the same chance of being in the experiment; this is called random sampling. If there are several strata of importance, random sampling from each stratum is appropriate. Convenience sampling is subject to the nuances of the surgical schedule, the goodwill of the referring physician and attending surgeon, and the willingness of the patient to cooperate. At best, a convenience sample is representative of patients at the institution, with no assurance that these patients are similar to those elsewhere. Convenience sampling is also the rule in studying new anesthetic drugs in volunteers; such studies typically are performed on “healthy, young students.” (See page 193: Sampling.) 2. An example of a contemporaneous-parallel control would be: A. Each patient could receive the standard drug under identical experimental circumstances at another time. B. A group of patients could have been studied previously with the standard drug under similar circumstances. C. Another group of patients receiving the standard drug could be studied simultaneously.
D. Literature reports show the effects of the drug under related but not necessarily identical circumstances. E. Each patient could receive the standard drug under nonexperimental conditions simultaneously with the test group. 2. C. A researcher can obtain comparative data in several ways: (1) each patient could receive the standard drug under identical experimental circumstances at another time; (2) another group of patients receiving the standard drug could be studied simultaneously; (3) a group of patients could have been studied previously with the standard drug under similar circumstances; or (4) literature reports of the effects of the drug under related (but not necessarily identical) circumstances could be used. Under the first two possibilities, the control group is contemporaneous, either self-control (crossover) or a parallel control group. The second two possibilities are examples of the use of historical controls. (See page 193: Control Groups.) 3. The risks of constructing a rigidly standardized study include all of the following EXCEPT: A. A fixed dose may produce excessive numbers of side effects in some patients. B. A standardized treatment may be so artificial that it has no broad clinical relevance. C. A fixed dose may be therapeutically insufficient in some patients. D. A fixed dose makes the research work more difficult. E. A fixed dose may not allow an effect or desired endpoint to be achieved. 3. D. The risks of constructing a rigidly standardized study do not include the likelihood that a fixed dose will make the research work more difficult. In contrast, standardizing the treatment groups by fixed doses simplifies the research work. There are risks to this standardization, however: (1) a fixed dose may produce excessive numbers of side effects in some patients, (2) a fixed dose may be therapeutically insufficient in others, and (3) a treatment standardized for an experimental protocol may be so artificial that it has no broad
clinical relevance even if it is demonstrated to be superior. The researcher should carefully choose and report the adjustment or individualization of experimental treatments. (See page 193: Experimental Constraints.) 4. The best method for random allocation of treatment groups is: A. based on the day of the week B. based on assignment of a previous patient C. using hospital chart numbers D. patient preference E. computer-generated random numbering 4. E. The experimental groups should be as similar to each other as possible in reflecting the target population; if the groups are different, this introduces a bias into the experiment. Although randomly allocating subjects of a sample to one or another of the experimental groups requires additional work, this principle prevents selection bias by the researcher, minimizes (but cannot always prevent) the possibility that important differences exist among the experimental groups, and disarms critics' complaints about research methods. Random allocation is most commonly accomplished by computer-generated random numbers. (See page 193: Random Allocation of Treatment Groups.) 5. Which statement about blinding is TRUE? A. It can bias a researcher's ability to administer the research protocol. B. It causes the researchers to not trust themselves to record the data impartially and dispassionately. C. It can be used in case reports. D. It masks from the patient and experimenters the experimental group to which the patient is assigned. E. It has the names single blind and double blind, which are often applied consistently but uncommonly in research reports 5. D. Blinding refers to the masking from the view of patient and experimenters the experimental group to which the subject has been or
will be assigned. In clinical trials, the necessity for blinding starts even before a patient is enrolled in the research study; this is called the concealment of random allocation. There is good evidence that if the process of random allocation is accessible to view, the referring physicians, the research team members, or both are tempted to manipulate the entrance of specific patients into the study to influence their assignment to a specific treatment group; they do so having formed a personal opinion about the relative merits of the treatment groups and desiring to get the “best” for someone they favor. This creates bias in the experimental groups. A researcher's knowledge of the treatment assignment can bias his or her ability to administer the research protocol and to observe and record data faithfully; this is true for clinical, animal, and in vitro research. If the treatment group is known, those who observe data cannot trust themselves to record the data impartially and dispassionately. (See page 194: Blinding.) 6. The most potent scientific tool for evaluating medical treatment is: A. A longitudinal prospective study of deliberate intervention with historical controls B. A longitudinal prospective study of deliberate intervention with concurrent controls C. A longitudinal retrospective study with concurrent case controls D. A longitudinal retrospective study with historical controls E. A cross-sectional prospective study without controls 6. B. The randomized, controlled clinical trial is the most potent scientific tool for evaluating medical treatment. Randomization into treatment groups is relied on to equally weight the subjects' baseline attributes that could predispose or protect the subjects from the outcome of interest. (See page 194: Types of Research Design.) 7. The error of failing to reject a false null hypothesis is called a: A. False-positive B. Type II error C. α error
D. Zero-order error E. Parameter 7. B. Because statistics deal with probabilities rather than certainties, there is a chance that the decision concerning the null hypothesis is erroneous. The error of wrongly rejecting the null hypothesis (falsepositive result) is called the type I or α error. The error of failing to reject a false null hypothesis (false-negative result) is called a type II or β error. A parameter is a number describing a variable of a population. (See page 197: Logic of Proof.) 8. The number of degrees of freedom and the value for each degree of freedom does NOT depend on: A. The type of statistical test B. The number of subjects C. Dividing the standard deviation by the square root of the sample size D. The specifics of the statistical hypothesis E. The number of experimental groups 8. C. The number of degrees of freedom and the value for each degree of freedom depends on the number of subjects, the number of experimental groups, the specifics of the statistical hypothesis, and the type of statistical test. (See page 198: Inferential Statistics.) 9. Variance is the: A. Statistical average B. Average deviation C. Average squared deviation D. Square root of the average deviation E. Square of the standard error 9. C. The concept of describing the spread of a set of numbers by calculating the average distance from each number to the center of the numbers applies to both samples and populations; this average squared distance is called the variance. (See page 196: Spread or Variability.)
P
10. The mean ± 3 standard deviation encompasses what percentage of the sample population? A. 50 B. 68 C. 75 D. 95 E. 99 10. E. Most biological observations appear to come from populations with normal or Gaussian distributions. By accepting this assumption of a normal distribution, further meaning can be given to the sample summary statistics that have been calculated. This involves the use of the expression &OV0335; ± κ × s, where k = 1, 2, 3, and so on. If the population from which the sample is taken is unimodal and roughly symmetric, then the bounds for 1, 2, and 3 encompasses roughly 68%, 95%, and 99% of the sample and population members. (See page 196: Spread or Variability.) 11. A study is performed looking at the difference in postoperative nausea in males and females undergoing laparoscopic cholecystectomy. The category “male or female” is an example of what kind of data? A. Ordinal B. Dichotomous C. Nominal D. Discrete interval E. Continuous interval 11. B. Dichotomous data allow only two possible variables. Ordinal data have three or more categories that can be logically ranked or ordered. Whereas discrete interval data can have only integer values (e.g., age in years), continuous interval data can be decimal fractions (e.g., temperature of 37.1°C). A nominal variable can be placed into a category that has no logical ordering (e.g., eye color). (See page 195: Data Structure and page 195: Table 9-2: Data Types.)
12. All of the following are aspects of enumeration data EXCEPT: A. They provide counts of subject responses. B. They provide a measure of central location of a binary data. C. They are also called categorical binary data. D. They provide a measure of central location for continuous data. E. They can be used to obtain a ratio of responders to the number of subjects. 12. D. Categorical binary data, also called enumeration data, provide counts of subject responses. Given a sample of subjects of whom some have a certain characteristic (e.g., death, female gender), a ratio of responders to the number of subjects can be easily calculated as P = x/n; this ratio or rate can be expressed as a decimal fraction or as a percentage. It should be clear that this is a measure of central location of binary data in the same way that μ is a measure of central location for continuous data. (See page 199: Confidence Intervals on Proportions.) 13. The most versatile approach for handling comparisons of means between more than two groups or between several measurements in the same group is called a/an: A. Paired t -test B. Chi-square test C. Interval data testing D. Analysis of variance (ANOVA) E. Unpaired t-test 13. D. The most versatile approach for handling comparisons of means between more than two groups or between several measurements in the same group is called ANOVA. The currently available nonparametric tests, such as the paired and unpaired t-tests, are not used more commonly because they do not adapt well to complex statistical models and they are less able than parametric tests to distinguish between the null and alternative hypotheses if the data are normally distributed. (See page 200: Analysis of Variance.)
14. Identify the slope and y-intercept for the following linear regression equation: y=a + bx A. a,b B. y,a C. y,b D. b,a E. x,y 14. D. In the simplest type of experiment, a straight line (linear relationship) is assumed between two variables; one (y), the response or dependent variable, is considered a function of the other (x), the explanatory or independent variable. This is expressed as the linear regression equation y = a + bx; the parameters of the regression equation are a and b. The parameter b is the slope of the straight line relating x and y; for each 1-unit change in x, there is a b unit change in y. The parameter a is the intercept (value of y when x equals 0). (See page 201: Linear Regression.) 15. Systematic differences between the patients receiving each intervention are called: A. Selection bias B. Performance bias C. Attrition bias D. Detection bias E. Experimenter bias 15. A. Selection bias is systematic differences between the patients receiving each intervention. Performance bias is systematic differences in care being given to study patients other than the preplanned interventions being evaluated. Attrition bias is systematic differences in the withdrawal of patients from each of the two intervention groups. Detection bias is systematic differences in the ascertainment and recording of outcomes. Experimenter bias occurs when the outcome of the experiment tends to be biased toward a result expected by the human experimenter. (See page 201: Systematic Reviews and MetaAnalyses.)
For questions 16 to 20, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 16. In dichotomous data testing: 1. The results are often presented as rate ratios 2. The chi-square test can analyze contingency tables with more than two rows and two columns 3. The Fishers exact test and the chi-square test allow comparison of the success rates between two sampled populations of a procedure 4. The chi-square test is computationally more complex than Fishers exact test 16. A. A variety of statistical techniques allow a comparison of success rate. These include Fishers exact test and (Pearson's) chi-square test. The chi-square test offers the advantage of being computationally simpler, and it can also analyze contingency tables with more than two rows and two columns. However, certain assumptions of sample size and response rate are not achieved by this test. (See page 199: Dichotomous Data Testing.) 17. The probability of a type II error increases with which of the following? 1. Small α value 2. Larger variability in populations being compared 3. Small difference between experimental conditions 4. Large sample size 17. A. The error of failing to reject a false null hypothesis (falsenegative) is called a type II or β error. The power of a test is 1 - β. The probability of a type II error depends on four factors. Unfortunately, the smaller the α, the greater the chance of a false-negative conclusion; this fact keeps the experimenter from automatically choosing a very small α. Second, the more variability there is in the populations being compared, the greater the chance of a type II error. This is analogous to listening to a noisy radio broadcast: The more static there is, the harder it will be to
discriminate between words. Third, increasing the number of subjects lowers the probability of a type II error. The fourth and most important factor is the magnitude of the difference between the two experimental conditions. The probability of a type II error goes from very high, when only a small difference exists, to extremely low, when the two conditions produce large differences in population parameters. (See page 197: Logic of Proof.) 18. Which of the following are summary statistics? 1. Mean 2. F ratio 3. Mode 4. P value 18. B. Although the results of a particular experiment may be presented by repeatedly showing the entire set of numbers, there are concise ways of summarizing the information content of the set into a few numbers. These numbers are called sample or summary statistics. The three most common summary statistics are the mean, median, and mode. (See page 196: Central Location.) 19. Nonparametric statistics: 1. Are used whenever there are serious concerns about the shape of the data 2. Do not require any assumptions about probability distributions of the populations 3. Are less able than parametric tests to distinguish between the null and alternative hypotheses if the data are normally distributed 4. Are also called “order statistics” 19. E. Statistical tests that do not require any assumptions about probability distributions of the populations are known as nonparametric tests; they can be used whenever there is very serious concern about the shape of the data. Nonparametric statistics are also the tests of choice for ordinal data. The basic concept behind nonparametric statistics is the ability to rank or order the observations; nonparametric tests are
also called order statistics. The currently available nonparametric tests are not used more commonly because they do not adapt well to complex statistical models, and they are less able than parametric tests to distinguish between the null and alternative hypotheses if the data are normally distributed. (See page 201: Robustness and Nonparametric Tests.) 20. Which of the following statements is/are TRUE? 1. A confidence interval describes how likely it is that the population parameter is estimated by any particular sample statistic such as the mean. 2. The standard error (SE) is used to describe the dispersion of the sample. 3. Sample size planning is important because it is the main mechanism for increasing statistical power. 4. Studies using historical controls obtain the same results as studies with concurrent controls if appropriate strata are selected. 20. B. The four options for decreasing type II error (increasing statistical power) are to increase the α, reduce the population variability, make the sample bigger, and make the difference between the conditions greater. Under most circumstances, only the sample size can be varied; thus, sample size planning has become an important part of research design for controlled clinical trials. When describing the spread, scatter, or dispersion of the sample, the standard deviation should be used; when describing the precision with which the population center is known, the SE should be used. A confidence interval describes how likely it is that the population parameter is estimated by any particular sample statistic such as the mean. Historical controls indicate a favorable outcome for a new therapy more often than concurrent controls (i.e., parallel control group or selfcontrol). If the outcome with an old treatment is not studied simultaneously with the outcome of a new treatment, one cannot know whether any differences in results are a consequence of the two treatments, of unsuspected and unknowable differences between the patients, or of other changes over time in the general medical
environment. (See page 198: Sample Size Calculations and page 198: Confidence Intervals.)
Chapter 10 Cardiovascular Anatomy and Physiology 1. Regarding the cardiac cycle, which of the following is FALSE? A. Left ventricle (LV) systole has three phases. B. Isovolumic contraction occurs after mitral valve closure. C. The decrease in ejection fraction (EF) is proportional to the decrease in LV function. D. Isovolumic contraction occurs in both the LV and right ventricle (RV). E. Diastasis allows free blood flow through the left atrium (LA). 1. D. LV systole is commonly divided into three parts: isovolumic contraction, rapid ejection, and slower ejection. Closure of both the tricuspid and mitral valves occurs when RV and LV pressures exceed the corresponding atrial pressure and causes the source of the first heart sound. Isovolumic contraction is the interval between closure of the mitral valve and the opening of the aortic valve. True isovolumic contraction does not occur in the RV because of the sequential nature of inflow followed by outflow during RV contraction. The normal LV enddiastolic volume is about 120 mL. The average ejected stroke volume is 80 mL, and the normal EF is approximately 67%. A decrease in EF below 40% is typically observed when the myocardium is affected by ischemia, infarction, or cardiomyopathic disease processes (e.g., myocarditis, amyloid infiltration). After left atrial and LV pressures have equalized, the mitral valve remains open, and pulmonary venous return continues to flow through the LA into the LV. This phase of diastole is known as diastasis, during which the LA functions as a conduit. Tachycardia progressively shortens and may completely eliminate this phase of diastole. Diastasis accounts for no more than 5% of total LV end-diastolic volume under normal circumstances. (See page 211: The Cardiac Cycle.) 2. Which statement regarding coronary circulation is FALSE?
A. The left coronary artery gives rise to the left anterior descending artery and the circumflex artery. B. Occlusive disease to the left anterior descending artery causes ischemic electrocardiographic (ECG) changes in leads V3, V4, and V5. C. The majority of blood supply to the atrioventricular (AV) node and common bundle of His is by the septal perforating branches of the left anterior descending artery. D. Occlusive disease to the right coronary artery results in ischemic ECG changes in leads II, III, and aVF. E. The sinus node is supplied by the right coronary artery. 2. C. In most patients, the right coronary artery supplies the sinus node, AV node, and common bundle of His. The left anterior descending artery supplies the AV node and common bundle of His in approximately 10% of hearts. The left anterior descending artery supplies the anterior left ventricle (LV), which is reflected in ECG leads V3 to V5. The circumflex artery supplies the posterior LV, which is reflected in ECG leads I and aVL. The right coronary artery supplies the inferior and diaphragmatic portions of the heart, as reflected in ECG leads II, III, and aVF. (See page 222: Coronary Circulation.) 3. Each of the following is a characteristic of cardiac and skeletal muscle fibers EXCEPT: A. Both sarcolemmas contain Na+ channels. B. Impulses reach the myocytes through “T transverse tubules.” C. Mitochondria are highly abundant in both types of fibers. D. Actin and myosin are the contractile proteins. E. They use transporter enzymes to regulate intracellular ion concentrations. 3. C. The sarcolemma is the external membrane of the cardiac muscle cell. The sarcolemma contains ion channels (e.g., Na+, K+, Ca2+), ion pumps and exchangers (e.g., Na+-K+ ATPase, Ca2+-ATPase, Na+-Ca2+ or H+ exchangers), G-protein–coupled and other receptors (e.g., β 1-
adrenergic, adenosine, opioid), and transporter enzymes. These regulate intracellular ion concentrations, facilitate signal transduction, and provide metabolic substrates required for energy production. Actin and myosin are the contractile proteins. Deep invaginations of the sarcolemma, known as transverse (“T”) tubules, penetrate the internal structure of the myocyte at regular intervals, ensuring rapid, uniform transmission of the depolarizing impulses that initiate contraction to be simultaneously distributed throughout the cell. Unlike the skeletal muscle cell, the cardiac myocyte is densely packed with mitochondria, which are responsible for generation of the large quantities of highenergy phosphates (e.g., adenosine triphosphate) required for the heart's phasic cycle of contraction and relaxation. The fundamental contractile unit of cardiac muscle is the sarcomere. (See page 213: Ultrastructure of the Cardiac Myocyte.) 4. Each of the following events results in hypotension EXCEPT: A. Urinary bladder retention B. Ocular globe pressure C. Valsalva maneuver D. Immersion of a hand in ice water E. Exposure to inhaled anesthetics 4. D. The arterial baroreceptor reflex appears to be especially important in short-term regulation of arterial pressure. Its effects (e.g., regulation of heart rate) are inhibited by volatile and many intravenous anesthetics. This inhibition of high-pressure baroreceptor reflexes by anesthetics involves several discrete sites, including sympathetic ganglionic transmission, end-organ responses, and central nervous system (CNS) pathways. The cold pressor reflex, which is activated by complete immersion of one hand in ice water, increases heart rate and mean arterial pressure (MAP). The cold environment causes local vasoconstriction to prevent heat loss and stimulates reflex CNS thermoregulatory receptors in the hypothalamic preoptic region to generate more widespread sympathetically mediated vasoconstriction. Somatic pain (as may be induced by the ice water) increases heart rate and MAP by activation of sympathetic efferent nerves. In contrast, visceral pain or distention of a hollow viscus (e.g., small intestine,
bladder) may produce reflex vagal bradycardia and hypotension. The oculocardiac reflex is activated by pressure on the ocular globe and causes pronounced bradycardia and hypotension by activation of vagal nerve fibers innervating the sinoatrial node. The Valsalva maneuver consists of forced expiration against a closed glottis. This maneuver reduces venous return to the right heart, decreases cardiac output and MAP, and increases heart rate. The reflex tachycardia occurs because of reduced activity of arterial baroreceptors and left ventricular mechanoreceptors. (See page 221: Other Cardiovascular Reflexes.) 5. The x descent: A. Is produced by atrial systole, coinciding with the P wave on the electrocardiogram (ECG) B. Results from the increasing intra-atrial pressure during atrial diastole C. Results from isovolumetric ventricular contraction, the period between closure of the atrioventricular (AV) valves and opening of the aortic and pulmonary valves D. Results from the opening of the AV valves, along with ventricular relaxation E. Results from forward blood flow and decreasing atrial pressure at the initiation of ventricular ejection 5. E. The a wave is produced by atrial systole, coinciding with the P wave on ECG. The v wave results from the increasing intra-atrial pressure during atrial diastole. The c wave results from isovolumetric ventricular contraction, the period between closure of the AV valves and opening of the aortic and pulmonary valves. The y descent results from the opening of the AV valves, along with ventricular relaxation. The x descent results from forward blood flow and decreasing atrial pressure at the initiation of ventricular ejection. (See page 211: The Cardiac Cycle.) 6. As a precipitant factor for myocardial infarction, which one is the MOST important? A. Platelets B. Fibrin
C. Calcium D. Cholesterol E. Mast cells 6. D. An atherosclerotic plaque is the most frequent cause of obstructed blood flow in large epicardial coronary artery vessels. The most common site for development of an atherosclerotic plaque is the first several centimeters of the major and coronary arteries and their primary branches. The position of atherosclerotic plaques facilitates their palliation by coronary artery bypass graft surgery. Atherosclerotic plaques typically develop very slowly, eventually protruding into the vessel and partially or completely blocking flow. The atherosclerotic plaque may also precipitate thrombus formation, which more rapidly occludes the coronary artery. A thrombus usually develops when the plaque has broken through the vascular intima, thereby exposing vascular smooth muscle or adventitia clotting factors and platelets contained in blood. When fibrin and platelets begin to be deposited, blood cells become entrapped and form a thrombus that grows rapidly until it produces a critical stenosis or complete occlusion of the coronary artery. The thrombus may also embolize by detaching from its original site of formation and flow to a more peripheral branch of the coronary arterial bed. Atherosclerotic plaques are composed of cholesterol and other lipids that become deposited beneath the intima and fibrous tissue, which also frequently becomes calcified. These calcium deposits are located predominantly at the junction of the intimal and medial layers of the blood vessel. (See page 225: Myocardial Ischemia and Infarction.) 7. Cardiac output is the product of heart rate and stroke volume. Several factors that affect cardiac output are P preload, afterload, heart rate, contractility, and ventricular compliance. All of the following statements are true EXCEPT: A. Cardiac index (cardiac output divided by body surface area) is normally 2.5 to 3.5 L/m2/min. B. Preload is determined by blood volume, venous tone, ventricular compliance, ventricular afterload, and myocardial
contractility. C. Left ventricular afterload depends on left ventricular geometry (shape, size, radius), aortic impedance, aortic wall stiffness, aortic blood mass, and blood viscosity. D. Cardiac output is increased at heart rates of greater than 160 bpm by increasing the extent and velocity of shortening of myocardial fibers and increased dP/dT. E. Increased contractility increases the ejection fraction (EF) if end-systolic volume (ESV) decreases while end-diastolic volume (EDV) remains the same. 7. D. Although cardiac output increases with increased heart rate, this increase becomes limited at heart rates of above 160 bpm. The rapid filling phase of diastole occurs in the first half-second of diastole. If diastole is shortened by increased heart rate, then ventricular filling is reduced, ultimately decreasing cardiac output. EF is determined by the equation EF = EDV - ESV/EDV. With increased contractility, ESV decreases. If EDV is unchanged, EF increases. (See page 212: Determinants of Cardiac Output.) 8. Regarding pulmonary physiology, which of the following is FALSE? A. Muscarinic receptors mediate bronchoconstriction. B. Pulmonary sympathetic effects originate in the thoracic spinal cord. C. Zone I represents dead space ventilation. D. Hypoxic pulmonary vasoconstriction is controlled by a welldefined receptor. E. Zone III represents a physiologic shunt. 8. D. The lung is richly innervated by the parasympathetic and sympathetic nervous systems. Vagal innervation of muscarinic receptors in airway smooth muscle produces bronchoconstriction and is an important contributing factor to bronchospasm in atopic pulmonary disease, pneumonia, and inhalation of noxious substances. The sympathetic innervation of the lung is derived from upper thoracic sympathetic fibers that innervate both airway and pulmonary vascular
smooth muscle. Sympathetic stimulation of airway smooth muscle produces bronchodilation by activation of β 2-adrenoceptors. The V/Q distribution within the lung in an upright position varies because of the effect of gravity. In the upper lung (zone 1), the V/Q ratio is greater than 1.0, indicating that alveolar ventilation occurs in excess of pulmonary blood flow. Because part of this zone is ventilated but not perfused, zone 1 contributes to dead space ventilation. In the middle region of the lung (zone 2), the V/Q ratio is close to 1.0, indicating a balance between ventilation and perfusion. In the lower regions of the lung (zone 3), the V/Q ratio is substantially lower than 1.0. Under these conditions, ventilation inadequately matches perfusion, and intrapulmonary shunt occurs. Pulmonary arteriolar vasoconstriction triggered by hypoxia shunts blood flow away from poorly to well ventilated regions of the lung, improving arterial O2 saturation. The mechanism by which hypoxia increases pulmonary vascular resistance appears to be mediated by an O2 sensor that is yet to be identified. (See page 227: Pulmonary Circulation.) 9. Which of the following occurs during cerebral autoregulation? A. The brain has relatively low blood flow. B. Cerebral oxygen consumption accounts for less than 1/8th of total body consumption. C. Autoregulation is preserved in subjects with poorly controlled hypertension. D. CO2 is a major regulator of cerebral blood flow. E. Therapeutic epinephrine produces significant decreases in blood flow. 9. D. The brain is approximately 2% of total body weight, yet it receives approximately 15% of cardiac output. This remarkably large cerebral blood flow (45–55 mL/100 g/min) reflects the brain's high metabolic rate. Cerebral oxygen consumption averages 3.5 mL/100 g/min and accounts for 20% of total body oxygen consumption at rest. Cerebral blood flow remains relatively constant when mean arterial pressure (MAP) varies between 50 and 150 mm Hg in healthy subjects. This autoregulation of cerebral blood flow shifted to the right in patients
with chronic, poorly controlled essential hypertension. For example, the autoregulation curve may range between 80 and 200 mm Hg in a patient with hypertension, and reducing the MAP below 80 mm Hg may precipitate cerebral ischemia. Arterial CO2 tension is a major regulator of cerebral blood flow within the physiologic range of arterial CO2 tensions. Cerebral blood flow linearly increases 1 to 2 mL/100 g/min for each 1–mm Hg increase in PaCO2. Below an arterial CO2 tension of 25 mm Hg, the cerebral blood flow response to PaCO2 is attenuated. Administration of exogenous vasodilators (e.g., sodium nitroprusside, adenosine, Ca2+ channel blockers, volatile anesthetics) increases cerebral blood flow. In contrast, catecholamines such as epinephrine do not substantially affect cerebral blood flow when these drugs are used to alter a systemic hemodynamics unless cerebral perfusion pressure is affected at the extremes of the autoregulation curve. (See page 228: Anatomy and Cerebral Autoregulation.) For questions 10 to 16, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 10. Which of the following is/are TRUE? 1. The P wave delineates atrial depolarization. 2. The QRS is larger than P wave because of the ventricular mass. 3. A PR delay occurs with atrioventricular blockade. 4. The ST segment is depressed during inadequate repolarization. 10. E. The first deflection of the electrocardiogram (ECG) is the P wave. (Einthoven began his depiction of the ECG in the middle of the alphabet.) The P wave is a positive deflection that occurs as a consequence of atrial depolarization. The initial electrical event is depolarization of the sinoatrial (SA) node pacemaker cells and is followed almost immediately by progressive depolarization of both atria. The PR interval is the duration between the onset of the P wave and the beginning of ventricular depolarization, which is signified by the onset of the QRS complex. Prolongation of the PR interval usually indicates a delay between atrial and ventricular conduction. The QRS complex records potentials at the body surface when the wave of depolarization
is distributed throughout ventricular myocardium. The QRS complex is much larger in magnitude than the P wave because the ventricular mass is greater than the atrial mass. The ST segment is the interval between the end of the QRS complex and the T wave. The ST segment is normally isoelectric because all of the ventricular myocardium is depolarized. The ST segment also reflects the long plateau phase of the cardiac action potential. The injury current of an elevated or depressed ST segment observed during myocardial ischemia or infarction may occur as a result of an abbreviated action potential within the ischemic region or because depolarizing currents propagate more slowly through the ischemic zone. (See page 217: The Clinical Electrocardiogram.) 11. The Bezold-Jarisch reflex: 1. Is transmitted via nonmyelinated C fibers resulting from stimulation of left ventricular mechanoreceptors 2. May be seen in response to reperfusion of previous ischemic myocardium 3. Is in response to noxious stimuli to the ventricular wall 4. Results in decreased parasympathetic tone, leading to tachycardia, hypertension, and coronary artery vasoconstriction 11. A. The Bezold-Jarisch reflex is initiated by left ventricular mechanoreceptors secondary to noxious ventricular stimuli. It results in increased parasympathetic activity, causing bradycardia, hypotension, and coronary artery vasodilation. Examples of stimuli include ischemia and reperfusion after ischemia (i.e., nitrate or heparin therapy, thrombolytic therapy, or coronary artery bypass graft). (See page 220: Baroreflex Regulation of Blood Pressure.) 12. Which of the following statements is/are TRUE? 1. Parasympathetic stimulation to the heart decreases heart rate via muscarinic receptors, decreasing adrenergic receptor activation through G-protein–mediated pathways. 2. Sympathetic stimulation occurs via α 1-, β 1-, and β 2-receptors through G-protein–mediated pathways.
3. The chronotropic and inotropic effects of β 1 activation result from increased numbers of calcium channels available for activation. 4. Sympathetic stimulation to the heart is via the stellate ganglia. 12. E. Parasympathetic stimulation to the heart decreases the heart rate via muscarinic receptors, thus decreasing adrenergic receptor activation through G-protein–mediated pathways. Sympathetic stimulation occurs via α 1-, β 1-, and β 2-receptors through G-protein– mediated pathways. The chronotropic and inotropic effects of β 1activation result from increased numbers of calcium channels available for activation. Sympathetic stimulation to the heart is via the stellate ganglia, which produces positive chronotropic, dromotropic, inotropic, and lusitropic effects. (See page 220: Baroreflex Regulation of Blood Pressure.) 13. Which of the following statements is/are TRUE? 1. Coronary arterial blood flow is determined by the duration of diastole, as well as the difference between aortic diastolic pressure and left ventricular (LV) end-diastolic pressure. 2. Right coronary artery flow occurs only during diastole. 3. Coronary blood flow is reduced in aortic insufficiency. 4. During periods of high oxygen demand, the myocardium can increase oxygen extraction by 20% to 25%. 13. B. Coronary flow occurs during diastole for the LV and during both diastole and systole in the right ventricle. The major determinants of coronary flow are aortic diastolic pressure and LV end-diastolic pressure. During systole, the LV subendocardium is exposed to a higher pressure than the subepicardial layer. Indeed, the systolic intraventricular pressure may be higher than the peak LV systolic pressure. Because of these differences in tissue pressure, the subendocardial layer is more susceptible to ischemia in the presence of coronary artery disease, pressure-overload hypertrophy, or pronounced tachycardia concomitant with compromised regional myocardial perfusion, a greater intraventricular–aortic pressure gradient, or reduced total diastolic flow, respectively. Coronary blood flow is also compromised when aortic
diastolic pressure is reduced (e.g., severe aortic insufficiency). Elevated LV end-diastolic pressure, as observed during acute heart failure, also reduces coronary blood flow because of decreases in coronary perfusion pressure. (See page 223: Mechanics of Coronary Blood Flow.) 14. Concerning coronary autoregulation, which of the following statements is/are correct? 1. Myocardial oxygen tension, acting through mediators such as adenosine, is a primary determinant of autoregulation. 2. Autoregulation varies between different myocardial layers. 3. Metabolic factors are major determinants of coronary blood flow. 4. “Coronary steal” occurs when pharmacologic vasodilation causes increased flow in normal arteries and away from stenotic arteries. 14. E. Myocardial oxygen tension, acting through mediators such as adenosine, is a primary determinant of autoregulation. Autoregulation varies among the different myocardial layers. Arteriolar vasodilation, which occurs to maintain coronary flow in stenotic vessels, is exhausted when the stenosis is above 90%. “Coronary steal” occurs when pharmacologic vasodilation causes increased flow in normal arteries and away from stenotic arteries. Sympathetic nervous system innervation modulates the contractile state of coronary vascular smooth muscle. In addition, smooth muscle tone is affected by stretch of the muscle (termed the “myogenic factor”). However, metabolic factors are the major physiologic determinants of coronary vascular tone and hence myocardial perfusion. The epicardial to endocardial blood flow ratio remains at near 1.0 throughout the cardiac cycle despite systolic compressive forces exerted on the subendocardium. The more pronounced resistance to flow in the subendocardium is offset by β adrenoceptor–mediated vasodilation and by local metabolic autocrine factors (e.g., adenosine) produced by the myocardium itself. (See page 225: Regulation of Coronary Blood Flow.) 15. Which of the following statements regarding specific peripheral circulations is/are TRUE?
1. Renal blood flow is autoregulated to maintain glomerular filtration. 2. Hypoxic pulmonary vasoconstriction is decreased by respiratory alkalosis. 3. The major site of resistance to portal flow is postsinusoidal. 4. Normal compensatory increases in venous tone resulting from decreased blood volume, posture change, or positive airway pressure are intact during anesthesia. 15. A. Renal blood flow is high to meet the metabolic demands of sodium reabsorption by the kidney and is autoregulated. Hypoxic pulmonary vasoconstriction is enhanced by metabolic acidosis, with no change resulting from respiratory acidosis. Both metabolic alkalosis and respiratory alkalosis decrease hypoxic pulmonary vasoconstriction. The major site of resistance to portal flow is postsinusoidal. Normal compensatory venous responses are abolished with autonomic neuropathy or during anesthesia. Thus, alterations to venous return caused by positive-pressure ventilation, change in posture, or decreased blood volume go uncompensated. (See page 227: Pulmonary Circulation and page 230: Splanchnic and Hepatic Circulation.) P P P P 16. When comparing myocardial supply with its demand, the following statement(s) is/are CORRECT: 1. The oxygen supply is dependent upon the diameter of the coronary arteries, left ventricular enddiastolic pressure, aortic diastolic pressure, and arterial oxygen content. 2. Coronary blood flow is influenced by intramyocardial pressure, heart rate, and blood viscosity. 3. The coronary perfusion pressure is the difference between the aortic diastolic pressure and left ventricular end-diastolic pressure.
4. Acidosis, hyperthermia, and increased 2,3-diphosphoglycerate (2,3-DPG) affect the myocardial oxygen supply. 16. E. A balance must always exist between oxygen consumption (demand) and myocardial oxygen supply if ischemia is to be avoided. Myocardial oxygen supply is dependent upon the diameter of the coronary arteries, left ventricular end-diastolic pressure, aortic diastolic pressure, and arterial oxygen content. In the normal heart, the coronary perfusion pressure is the difference between the aortic diastolic pressure and the left ventricular end-diastolic pressure. Myocardial blood flow is determined by the blood pressure at the coronary ostia, arteriolar tone, intramyocardial pressure or extravascular resistance, coronary occlusive disease, heart rate, coronary collateral development, and blood viscosity. Myocardial oxygen supply is also affected by the level of arterial oxygenation. Oxygen content resulting from changes in PaO2, hemoglobin, DPG, pH, PCO2, or temperature can affect the oxyhemoglobin dissociation curve and can be important in patients with obstructive lung disease or severe anemia. (See page 225: Oxygen Delivery and Demand.)
Chapter 11 Respiratory Function 1. Which of the following statements regarding lung compliance is FALSE? A. Diseases that decrease lung compliance typically result in increased respiratory rates. B. Spontaneous respiratory rate is a poor indicator of lung compliance. C. Continuous positive airway pressure (CPAP) improves lung compliance and therefore lowers the work of breathing in patients with reduced compliance. D. Diseases that increase lung compliance typically result in increased functional residual capacity (FRC). E. Significant increases in lung compliance may require the use of the ventilatory muscles to exhale actively. 1. B. When lung compliance is small, larger changes in intrapleural pressure are needed to create the same tidal volume (Vt) (i.e., one has to inhale harder to force the same volume of gas into the lungs). Thus, patients with low lung compliance typically breathe with a smaller Vt at more rapid rates. Spontaneous ventilatory rate is one of the most sensitive indices of lung compliance. CPAP shifts the vertical line to the right, allowing the patient to breathe on a steeper and more favorable portion of the volume–pressure curve. This results in a slower ventilatory rate with a larger Vt. Patients with diseases that increase lung compliance have larger than normal FRCs (gas trapping) and pressure– volume curves that are shifted to the left and steeper. These patients expend less elastic work to inspire, but elastic recoil is reduced significantly. COPD and acute asthma are the most common examples of diseases with high lung compliance. If lung compliance and FRC are sufficiently high (elastic recoil is minimal), the patient must use the ventilatory muscles to expire actively. (See page 236: Elastic Work.)
2. Which of the following statements regarding ventilation–perfusion (V/Q) matching is TRUE? A. West zone 1 can be best characterized as physiologic shunt. B. West zone 1 can be increased by increasing pulmonary artery pressure (PPA). C. West zone 3 occurs above the level of the third rib in the sitting position. D. West zone 3 has PPA > Pulmonary venous pressure (PPV)> Alveolar pressure (PA) and therefore has perfusion in excess of ventilation. E. In west zone 1, pulmonary capillary wedge pressure (PCWP) is transmitted to the alveoli promoting alveolar collapse, resulting in no ventilation of this area. 2. D. Zone 1 receives ventilation in the absence of perfusion and creates alveolar dead space ventilation. Normally, zone 1 areas exist only to a limited extent. However, in conditions of decreased PPA, such as hypovolemic shock, zone 1 enlarges. Because PA is approximately equal to atmospheric pressure, PPA in zone 1 is subatmospheric but necessarily greater than PPV (PA > PPA > PPV). PA that is transmitted to the pulmonary capillaries promotes their collapse, with a consequent theoretical blood flow of zero to this lung region. Thus, zone 1 receives ventilation in the absence of perfusion and creates alveolar dead space ventilation. Zone 3 occurs in the most gravity-dependent areas of the lung, where PPA > PPV > PA and blood flow is primarily governed by the PPA to PPV difference. Because gravity also increases PPV, the pulmonary capillaries become distended. Thus, perfusion in zone 3 is lush, resulting in capillary perfusion in excess of ventilation, or physiologic shunt. The pressure difference between PPA and PA determines blood flow in zone 2. PPV has little influence. Well-matched ventilation and perfusion occur in zone 2, which contains the majority of alveoli. (See page 243: Distribution of Blood Flow.) 3. Functional residual capacity (FRC): A. Is the maximal volume that can be exhaled in a single breath
B. Is increased by mechanical factors such as obesity and pregnancy C. Can be used to quantify the degree of pulmonary restriction D. Is significantly increased in the supine position E. Is markedly reduced in patients with chronic obstructive pulmonary disease (COPD) 3. C. FRC is the volume of gas remaining in the lungs at passive end expiration. Residual volume is the gas remaining within the lungs at the end of forced maximal expiration. The FRC may also be used to quantify the degree of pulmonary restriction. Disease processes that reduce FRC and lung compliance include acute lung injury, pulmonary edema, pulmonary fibrotic processes, and atelectasis. Mechanical factors also reduce FRC (e.g., pregnancy, obesity, and pleural effusion). The FRC decreases 10% when a healthy subject lies down. Ventilatory muscle weakness and paralysis also decrease FRC. In contrast, patients with COPD have excessively compliant lungs that recoil less forcibly. Their lungs retain an abnormally large volume at the end of passive expiration, a phenomenon called gas trapping. (See page 247: Lung Volumes and Capacities.) 4. Which of the following tests is most useful and cost effective in screening overall pulmonary function? A. The flow–volume loop B. The CO2 diffusing capacity of the lungs (DLCO) C. The maximum voluntary ventilation D. Spirometry measurements E. Blood gas analysis 4. D. Although we have a host of pulmonary function tests from which to choose, spirometry is the most useful, cost-effective, and most commonly used test. (See page 249: Pulmonary Function Tests Summary.) 5. Which of the following statements regarding postoperative pulmonary function is TRUE?
A. The changes in postoperative pulmonary function are primarily obstructive. B. Postoperative spontaneous ventilation is characterized by the absence of sighs. C. Thoracic operations have a more severe impact on functional residual capacity (FRC) than nonlaparoscopic upper abdominal operations. D. The normal postoperative respiratory rate is 12 to 13 breaths/min. E. Intracranial procedures typically decrease FRC by 40% to 50%. 5. B. The changes in pulmonary function that occur postoperatively are primarily restrictive, with proportional decreases in all lung volumes and no change in airway resistance. This defect is generated by abdominal contents that impinge on and prevent normal movement of the diaphragm and an abnormal respiratory pattern that is shallow, rapid, and devoid of sighs. Whereas the normal resting respiratory rate for adults is 12 breaths/min, postoperative patients usually breathe approximately 20 breaths/min. The operative site is one of the single most important determinants of the degree of pulmonary restriction and the risk of postoperative pulmonary complications. Nonlaparoscopic upper abdominal operations cause the most profound restrictive defect, precipitating a 40% to 50% decrease in FRC compared with preoperative levels when conventional postoperative analgesia is used. Lower abdominal and thoracic operations cause the next most severe change in pulmonary function, with decreases in FRC to 30% of preoperative levels. Most other operative sites, including intracranial, have approximately the same effect on FRC, with reductions to 15% to 20% of preoperative levels. (See page 253: Postoperative Pulmonary Function.) 6. The maximum benefit from preoperative smoking cessation occurs at approximately: A. 24 hours B. 2 days C. 2 weeks D. 4 weeks
E. 8 weeks 6. E. Patients who smoke should be advised to stop smoking 2 months before elective operations to maximize the effect of smoking cessation or for at least 4 weeks to gain some benefit from improved mucociliary function. Normalization of mucociliary function requires 2 to 3 weeks of abstinence from smoking, during which time sputum increases. Several months of smoking abstinence are required to return sputum clearance to normal. If patients cannot stop smoking for these periods of time, they probably should be advised to stop smoking for at least 24 hours before the operation so that carboxyhemoglobin levels will approach normal. Smokers who decrease but do not stop cigarette consumption without the aid of nicotine replacement therapy continue to acquire equal amounts of nicotine from fewer cigarettes by changing their technique of smoking to maximize nicotine intake. (See page 252: Effects of Cigarette Smoking on Pulmonary Function.) 7. Which of the following statements regarding cigarette smoking and lung disease is FALSE? A. Smoke increases mucus production and decreases ciliary motility. B. Smoking leads to a decrease in proteolytic enzymes in the lung that directly cause damage to lung parenchyma. C. Patients with chronic obstructive pulmonary disease (COPD) who smoke have up to a sixfold greater risk of developing postoperative pneumonia than nonsmokers. D. Normalization of mucociliary activity requires at least 2 to 3 weeks of abstinence from smoking. E. Smokers' relative risk of postoperative pulmonary complications is doubled even in the absence of clinical pulmonary disease and abnormal pulmonary function test results. 7. B. Smoking affects pulmonary function in many ways. The irritant smoke decreases ciliary motility and increases sputum production. Thus, these patients have a high volume of sputum and decreased ability to clear it effectively. As smoking habits persist, airway reactivity and the development of obstructive disease become problematic. Studies of the pathogenesis of COPD suggest that smoking results in an excess of
P
pulmonary proteolytic enzymes that directly cause damage to the lung parenchyma. Exposure to smoke increases synthesis and release of elastolytic enzymes from the alveolar macrophages, cells instrumental in the genesis of COPD resulting from smoking. Smoking is one of the main and most prevalent risk factors associated with postoperative morbidity. Patients with COPD who smoke have a two- to a sixfold risk of developing postoperative pneumonia compared with nonsmokers. Furthermore, smokers' relative risk of postoperative pulmonary complications is doubled, even if they do not have evidence of clinical pulmonary disease or abnormal pulmonary function. Normalization of mucociliary function requires 2 to 3 weeks of abstinence from smoking, during which time sputum increases. (See page 252: Effects of Cigarette Smoking on Pulmonary Function.) 8. All of the following strategies reduce the risk of postoperative pulmonary complications EXCEPT: A. Anesthetic technique B. Postoperative pain management C. Incentive spirometry D. Stir-up regimens E. Intermittent continuous positive airway pressure (CPAP) by mask 8. A. There are several strategies by which it is possible to reduce the risk of postoperative pulmonary complications, including use of lungexpanding therapies after surgery, choice of analgesia, and cessation of smoking. After upper abdominal operations, which are associated with the highest incidence of postoperative pulmonary complications, functional residual capacity (FRC) recovers over 3 to 7 days. With the use of intermittent CPAP by mask, FRC recovers within 72 hours. Patients use incentive spirometers correctly only 10% of the time unless therapy is supervised. Stir-up regimens are as effective as incentive spirometry at preventing postoperative pulmonary complications and are less expensive than supervised incentive spirometry, so they are preferred over incentive spirometry therapy. The choice of anesthetic technique for intraoperative anesthesia does not change the risk of postoperative pulmonary complications, but the choice of postoperative analgesia
strongly influences the risk of these complications. The advent of postoperative epidural analgesia, particularly for abdominal and thoracic operations, has markedly decreased the risk of postoperative pulmonary complications and appears to contribute to decreased length of stay in the hospital postoperatively. (See page 253: Postoperative Pulmonary Complications.) 9. When diaphragm function is impaired in patients with cervical spinal cord transection, which of the following act as primary inspiratory muscles? A. Intercostal muscles B. Cervical strap muscles C. Abdominal muscles D. Intervertebral muscles of the shoulder girdle E. Sternocleidomastoid muscles 9. B. The ventilatory muscles include the diaphragm, intercostal muscles, abdominal muscles, cervical strap muscles, sternocleidomastoid muscles, and large back and intervertebral muscles of the shoulder girdle. During breathing, the diaphragm performs most of the muscle work. Work contribution from the intercostal muscles is minor. With an increase in work, the cervical strap muscles help elevate the sternum and upper portions of the chest. The cervical strap muscles, active even during breathing at rest, are the most important inspiratory accessory muscles. When diaphragm function is impaired, as in patients with cervical spinal cord transaction, they can become the primary inspiratory muscles. During periods of maximal work, the large back and paravertebral muscles of the shoulder girdle contribute to ventilatory effort. The abdominal wall muscles are the most powerful muscles of expiration. (See page 234: Functional Anatomy of the Lungs.) 10. Which is the last airway component that is incapable of gas exchange? A. Respiratory bronchiole B. Terminal bronchiole C. Alveolar ducts
D. Mainstem bronchi E. Alveolar sacs 10. B. The airway generation next to trachea is composed of the right and left mainstem bronchi. The next generation consists of bronchioles, of which the final generation is terminal bronchiole; this is the last airway component incapable of gas exchange. The respiratory bronchiole, which follows the terminal bronchiole, is the first site in the tracheobronchial tree where gas exchange occurs. In adults, two or three generations of respiratory bronchioles lead to alveolar ducts, of which there are four to five generations, each with multiple openings into alveolar sacs. (See page 234: Lung Structures.) 11. Which of the following statements regarding type 1 cells is FALSE? A. They contain extremely thin cytoplasmic extensions that provide surface for gas exchange. B. They are highly differentiated. C. They cover 80% of the alveolar surface. D. They are very resistant to injury. E. They are metabolically limited. 11. D. Type 1 alveolar cells cover approximately 80% of the alveolar surface. Type 1 cells contain flattened nuclei and extremely thin cytoplasmic extensions that provide the surface for gas exchange. They are highly differentiated and metabolically limited, which makes them highly susceptible to injury. (See page 234: Lung Structures.) 12. Which of the following primarily limits the depth of inspiration? A. Pneumotaxic center B. Apneustic center C. Ventral respiratory group D. Dorsal respiratory group E. Reticular activating system 12. A. The primary function of the pneumotaxic center is to limit the depth of inspiration. When maximally activated, the pneumotaxic center
secondarily increases ventilatory frequency. However, it performs no pacemaking function and has no intrinsic rhythmicity. The dorsal respiratory group is the source of elementary ventilatory rhythmicity and serves as the pacemaker for the respiratory system. The ventral respiratory group serves as the expiratory coordinating center. With activation, the apneustic center sends impulses to inspiratory dorsal respiratory group neurons and is designed to sustain inspiration. (See page 239: Generation of Ventilatory Pattern.) 13. Which of the following does not cause absolute or true shunt? A. Acute lobar atelectasis B. Extensive acute lung injury C. Advanced pulmonary edema D. Pulmonary embolus E. Consolidated pneumonia 13. D. Physiologic shunt occurs in a lung that is perfused but poorly ventilated. Physiologic shunt is the portion of the total cardiac output that returns to the left heart and systemic circulation without receiving oxygen in the lung. Diseases that cause absolute or true shunt include acute lobar atelectasis, extensive acute lung injury, advanced pulmonary edema, and consolidated pneumonia. Physiologic dead space ventilation applies to areas of the lung that are ventilated but poorly perfused as in pulmonary embolus. (See page 246: Physiologic Shunt.) 14. Which of the following statements is FALSE about the CO2 diffusing capacity of the lungs (DLCO)? A. Decreased hemoglobin concentration decreases the DLCO. B. DLCO values increase two to three times normal during exercise. C. DLCO is decreased in obstructive disease states. D. Decreased alveolar PCO2 increases DLCO. E. Low DLCO is related to loss of lung volume or capillary bed perfusion.
14. D. DLCO collectively measures all of the factors that affect the diffusion of gas across the alveolar capillary membrane. DLCO values may increase to two or three times normal during exercise. Decreased hemoglobin concentration decreases DLCO. An increased PACO2 increases DLCO. Low DLCO is more closely related to loss of lung volume or capillary bed perfusion. DLCO is decreased in all obstructive disease states. (See page 249: Carbon Monoxide Diffusing Capacity.) For questions 15 to 23, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 15. Which of the following components comprise the alveolar wall? 1. Thin capillary epithelial cell 2. Basement membrane 3. Pulmonary capillary endothelial cell 4. Surfactant lining layer 15. E. The alveolar–capillary interface is well designed to facilitate gas exchange. The alveolar wall consists of a thin capillary epithelial cell, basement membrane, pulmonary capillary endothelial cell, and surfactant lining layer. (See page 234: Lung Structures.) 16. Which of the following conditions changes laminar flow to turbulent flow? 1. High gas flows 2. Sharp angles within the tube 3. Branching in the tube 4. Decrease in the tube's diameter 16. E. Four conditions that change laminar flow to turbulent flow are high gas flows, sharp angles within the tube, branching in the tube, and a decrease in the tube's diameter. During laminar flow, resistance is inversely proportional to the gas flow rate. During turbulent flow, resistance increases significantly in proportion to the flow rate. (See page 237: Turbulent Flow.)
17. Which of the following statements regarding the trachea is/are TRUE? 1. In the supine position, the most likely place for aspirated material to fall is the right upper lobe. 2. It is totally intrathoracic, with 50% in the superior mediastinum and 50% in the inferior mediastinum. 3. The tracheal bifurcation is usually at the level of T4. 4. The trachea's fixed position in the inferior mediastinum serves as an important reference point. 17. B. The diameter of the right bronchus is generally greater than that of the left. In adults, whereas the right bronchus leaves the trachea at approximately 25 degrees from the tracheal axis, the angle of the left bronchus is approximately 45 degrees. Thus, inadvertent endobronchial intubation or aspiration of foreign material is more likely to occur in the right lung than in the left. Furthermore, the right upper lobe bronchus dives almost directly posterior at approximately 90 degrees from the right main bronchus. Foreign bodies and fluid aspirated by a supine subject usually fall into the right upper lobe. In adults, the trachea is a fibromuscular tube approximately 10 to 12 cm long with an outside diameter of approximately 20 mm. The trachea enters the superior mediastinum and bifurcates at the sternal angle (the lower border of the fourth thoracic vertebral body). Normally, half of the trachea is intrathoracic, and the other half is extrathoracic. Both ends of the trachea are attached to mobile structures. Thus, the carina can move superiorly as much as 5 cm from its normal resting position. (See page 235: Conductive Airways.) 18. Which of the following statements regarding bronchioles is/are TRUE? 1. They are approximately 1 mm in diameter. 2. They are the last segment of the conducting airways to contain cartilage. 3. They have the highest proportion of smooth muscle in their walls.
4. The terminal bronchioles may be involved in terminal gas exchange if they are recruited. 18. B. The bronchioles typically have diameters of 1 mm. They are devoid of cartilaginous support and have the highest proportion of smooth muscle in the wall. There are approximately three to four bronchiolar generations. The final bronchiolar generation is the terminal bronchiole, which is the last airway component that is not directly involved in gas exchange. (See page 235: Conductive Airways.) P P P P 19. Which of the following characteristics regarding gas flow is/are TRUE? 1. With laminar gas flow, significant alveolar ventilation can occur, even when tidal volume (Vt) is less than dead space. 2. Density is the only physical gas property that is relevant under laminar gas flow conditions. 3. Helium does not improve gas flow under laminar conditions. 4. During turbulent flow, resistance decreases in proportion to flow rate. 19. B. A clinical implication of laminar flow in the airways is that significant alveolar ventilation can occur even when the Vt is less than anatomic dead space. This phenomenon is important in high-frequency ventilation. Viscosity is the only physical gas property that is relevant under conditions of laminar flow. Helium has a low density, but its viscosity is close to that of air. Therefore, helium will not improve gas flow that is laminar. Flow is usually turbulent when there is critical airway narrowing or abnormally high airway resistance, thus making lowdensity helium therapy useful. Resistance during laminar flow is inversely proportional to gas flow rate. Conversely, during turbulent flow, resistance increases in proportion to the flow rate. (See page 237: Resistance to Gas Flow.) 20. The Hering-Breuer reflex:
1. Is blocked by bilateral vagotomy 2. Produces apnea in humans when continuous positive airway pressure (CPAP) exceeds 40 cm H2O 3. Is a pulmonary stretch reflex that is primarily generated from the intercostal muscles but not the diaphragm 4. Is prominent in humans but not lower-order mammals 20. B. The Golgi tendon organs (tendon spindles), which occur in series arrangements within ventilatory muscles, facilitate proprioception. Whereas the intercostal muscles are rich in tendon spindles, the diaphragm has a limited number. Thus, the pulmonary stretch reflex primarily involves the intercostal muscles but not the diaphragm. When the lungs are full and the chest wall is stretched, these receptors send signals to the brainstem, further inhibiting inspiration. In 1868, Hering and Breuer reported that lightly anesthetized, spontaneously breathing animals cease or decrease ventilatory effort during sustained lung distention. This response was blocked by bilateral vagotomy. The HeringBreuer reflex is prominent in lower-order mammals, such as rabbits, but is only weakly present in humans. This reflex is sufficiently active in lower mammals, such that 5 cm H2O CPAP induces apnea. In humans, however, the reflex is only weakly present, as evidenced by the fact that humans continue to breathe spontaneously with CPAP in excess of 40 cm H2O. This inflation reflex is associated with inspiratory muscle inhibition, as documented by marked reductions in the electrical activity of both the phrenic nerve and the diaphragmatic muscle itself. The second component of the Hering-Breuer reflex, the deflation reflex, produces increased ventilatory muscle activity after sustained lung deflation. (See page 240: Reflex Control of Ventilation.) 21. Which of the following result(s) in an enhanced CO2 response (shift of CO2 response curve upward and to the left)? 1. Anxiety 2. Metabolic acidosis 3. Arterial hypoxemia 4. Opioid antagonists in the absence of opioids
21. A. Three clinical states result in a left shift or a steepened slope of the CO2 response curve. These same three situations are the only causes of true hyperventilation (i.e., an increase in minute ventilation such that the decreased PaCO2 creates respiratory alkalemia). The three causes of hyperventilation (enhanced CO2 response) are arterial hypoxemia, metabolic acidemia, and central etiologic factors. Examples of central etiologic factors that cause hyperventilation include drug administration, intracranial hypertension, hepatic cirrhosis, and nonspecific arousal states such as anxiety and fear. Aminophylline, salicylates, and norepinephrine stimulate ventilation independent of peripheral chemoreceptors. Opioid antagonists, given in the absence of opioids, do not stimulate ventilation. However, when they are given after opiate administration, they do reverse the effects of opioids on the CO2 response curve. (See page 242: Quantitative Aspects of Chemical Control of Breathing.) 22. Inspiratory capacity: 1. Is defined as the greatest volume that can be inhaled from the resting expiratory level 2. Is commonly measured as part of routine pulmonary function testing 3. Can be a sensitive indicator of extrathoracic airway obstruction 4. Is less sensitive than expiratory measurements to extrathoracic obstruction 22. B. The inspiratory capacity is the largest volume of gas that can be inspired from the resting expiratory level and is frequently decreased in the presence of significant extrathoracic airway obstruction. This measurement is one of the few simple tests that can detect extrathoracic airway obstruction. Most routine pulmonary function tests measure only exhaled flows and volumes, which are relatively unaffected by extrathoracic obstruction unless it is severe. Changes in the absolute volume of inspiratory capacity usually parallel changes in vital capacity. Expiratory reserve volume is not of great diagnostic value. (See page 247: Lung Volumes and Capacities.) 23. Which of the following statements is/are TRUE?
1. The direct effect of CO2 on central chemoreceptors is responsible for more than 80% of the resultant increase in ventilatory response. 2. A sudden decrease in the pressure of end-tidal CO2 (PETCO2) in a mechanically ventilated patient is most often caused by pulmonary air embolism. 3. Preoperative pulmonary function testing is important in predicting the likelihood of postoperative pulmonary complications. 4. Patients having intrathoracic operations are at a slightly lower risk of experiencing postoperative pulmonary complications than patients having abdominal operations. 23. D. Although the central response is the major factor in the regulation of breathing by CO2, CO2 has little direct stimulating effect on these chemosensitive areas. These receptors are primarily sensitive to changes in H+ concentration. CO2 has a potent but indirect effect by reacting with water to form carbonic acid, which dissociates into H+ and bicarbonate ions. The PETCO2 in ventilated patients varies linearly with the dead space (Vd) to tidal volume (Vt) ratio (Vd/Vt) and correlates poorly with PaCO2. Monitoring PETCO2 gives far more information about ventilatory efficiency or Vd than it does about the absolute value of PaCO2. Anesthesiologists commonly measure PETCO2 to detect venous air embolism during anesthesia. A lowered cardiac output alone, in the absence of venous air embolism, may sufficiently decrease pulmonary perfusion so that Vd increases and PETCO2 decreases. Thus, a depressed PETCO2 is a sensitive but nonspecific monitor. The goals one hopes to achieve through preoperative pulmonary function testing are to predict the likelihood of pulmonary complications, obtain quantitative baseline information concerning pulmonary function, and identify patients who may benefit from therapy to improve pulmonary function preoperatively. For patients who will have lung resection, pulmonary function testing provides some predictive benefit. However, for other patients, the overwhelming evidence suggests that preoperative pulmonary function testing does not predict or assign risk for postoperative pulmonary complications. The operative site is the
single most important determinant of both the degree of pulmonary restriction and postoperative pulmonary complications. Nonlaparoscopic upper abdominal operations increase the risk of postoperative pulmonary complications by at least twofold. Lower abdominal and intrathoracic operations are associated with slightly lower risk but still higher risk than extremity, intracranial, and head and neck operations. (See page 241: Central Chemoreceptors: Assessment of Physiologic Dead Space; page 253: Postoperative Pulmonary Complications; and page 250: Preoperative Pulmonary Assessment.)
Chapter 12 Immune Function and Allergic Response 1. The humoral defense system includes all the following EXCEPT: A. Antibodies B. Cytokines C. Complement D. Lymphocytes E. Circulating proteins 1. D. The host defense systems can be divided into cellular and humoral elements. The humoral system includes complement, cytokines, antibodies, and other circulating proteins. The cellular system defense is mediated by specific lymphocytes of the T-cell series. (See page 257: Basic Immunologic Principles.) 2. Which type of T cell does not require specific antigen stimulation to initiate its function? A. Cytotoxic B. Lymphotrophic C. Suppressor D. Helper E. Killer 2. E. The thymus of the fetus differentiates immature lymphocytes into thymus-derived cells (T cells). The two types of regulator T cells are helper cells and suppressor cells. Helper cells are important for effective cell responses. Suppressor cells inhibit immune function. Killer cells do not require specific antigen stimulation to initiate their function. Cytotoxic T cells destroy mycobacteria, fungi, and viruses. (See page 257: Basic Immunologic Principles: Thymus-Derived Lymphocytes [T-Cell] and Bursa-Derived Lymphocytes [B-Cell].)
3. Which of the following statements regarding antibodies is TRUE? A. Each antibody has two heavy chains and one light chain. B. The Fab segment binds the antigen. C. The light chain is responsible for the unique biologic properties of the different classes of immunoglobulins. D. There are six major classes of antibodies in humans. E. The light chain determines the structure and function of each molecule. 3. B. Each antibody has two heavy chains and two light chains that are bound together by disulfide bonds. Whereas the Fab fragment has the ability to bind antigen, the Fc (crystallizable) is responsible for the unique biologic properties of the different classes of immunoglobulins. The five major classes of antibodies in humans are IgG, IgA, IgM, IgD, and IgE. The heavy chain determines the structure and function of each molecule. (See page 257: Basic Immunologic Principles: Antibodies.) 4. The attachment of an antibody or complement fragment to the surface of foreign cells is called: A. Immunogenicity B. Hepatogenicity C. Opsonization D. Lymphotropism E. Lymphokinesis 4. C. The attachment of an antibody or complement fragment on the surface of foreign cells is called opsonization, a process that facilitates effector cell killing of foreign cells. Haptens are small molecules that form bonds with either host proteins or cell membranes to form a complete antigen. The ability to act as an antigen is referred to as immunogenicity. (See page 257: Basic Immunologic Principles: Effector Cells and Proteins of the Immune Response Cells.) 5. Which kind of cells regulate immune responses by presenting antigens to result in microbicidal function? A. Eosinophils
B. Basophils C. Neutrophils D. Mast cells E. Macrophages 5. E. Neutrophils are the first cells to appear in an acute inflammatory reaction. Eosinophils accumulate at sites of parasitic infection, tumor, and allergic reactions. Mast cells are tissue fixed and located in the perivascular spaces of the skin and intestine; when they are activated, they release a broad spectrum of physiologically active mediators. Basophils possess IgE receptors on their surfaces and function similarly to mast cells. Macrophages regulate immune responses by presenting antigens to result in microbicidal function. (See page 257: Basic Immunologic Principles: Effector Cells and Proteins of the Immune Response Cells.) 6. Complement can be activated by all of the following EXCEPT: A. Immunoglobulin G (IgG) B. Plasmin C. Killer T cells D. Endotoxin E. The alternate pathway 6. C. The primary humoral response to antigen and antibody binding is the activation of the complement system. Complement activation can be initiated by IgG or IgM, by plasmin through the classic pathway, by endotoxin, or by drugs through the alternate (properdin) pathway. The major function of the complement system is to recognize bacteria, both directly and indirectly by the attraction of phagocytes, as well as the increased adhesion of phagocytes to antigens and cell lysis through activation of the complement system. T cells are a component of the cellular immune response system. (See page 257: Basic Immunologic Principles: Effector Cells and Proteins of the Immune Response Cells [Complement].)
7. True statements concerning the secondary treatment of anaphylaxis include all of the following EXCEPT: A. Bicarbonate should be given to treat severe acidemia. B. Corticosteroids require 12 to 24 hours to work. C. Corticosteroids are recommended for IgE-mediated reactions. D. Antihistamines inhibit histamine release. E. Catecholamines, such as epinephrine, can be used if bronchospasm is present. 7. D. Administration of a histamine (H1) antagonist may be useful in treating acute anaphylaxis; it does not inhibit H1 release but competes with H1 at the receptor sites. Steroids should be considered a secondary treatment in the management of patients with anaphylactic bronchospasm. Steroids require 12 to 24 hours to exert their peak clinical effect. Although the exact corticosteroid dose and preparation are unclear, investigators have recommended 0.25 to 1 g intravenously of hydrocortisone for IgE-mediated reactions. Acidosis frequently accompanies persistent hypotension. Acidemia decreases the effectiveness of administered epinephrine on the myocardium. Therefore, with refractory hypotension and acidemia, sodium bicarbonate should be given as indicated by arterial blood gas evaluation. Catecholamines, such as epinephrine, can be used in patients with persistent hypotension or bronchospasm after initial resuscitation. (See page 260: Anaphylactic reactions: Non–IgE-Mediated Reactions [Nonimmunologic Release of Histamine, Treatment Plan, and Secondary Treatment].) 8. The purpose of _________________ is to determine basophil activation. A. skin testing B. the leukocyte histamine release test C. enzyme-linked immunosorbent assay (ELISA) D. the radioallergosorbent test E. the protamine test
8. B. The leukocyte histamine release test is performed by incubating the patient's leukocytes with the offending drug and measuring the histamine release as a marker for basophil activation. The radioallergosorbent test allows in vitro detection of specific IgE directed toward particular antigens by linking them to insoluble material to make them immunoabsorbent. ELISA measures antigen-specific antibodies. (See page 266: Perioperative Management of the Patient with Allergies: Evaluation of Patients with Allergic Reactions [Testing for Allergy].) For questions 9 to 14, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 9. Type II reactions include all of the following EXCEPT: 1. ABO incompatibility reactions 2. Heparin-induced thrombocytopenia 3. Drug-induced immune hemolytic anemia 4. Classic serum sickness 9. D. Type II reactions are also known as antibody-dependent cellmediated cytotoxic hypersensitivity reactions. These reactions are mediated by IgG or IgM antibodies directed against antigens on the surface of foreign cells. Examples of type II reactions in humans are ABO-incompatible transfusion reactions, drug-induced immune hemolytic anemia, and heparin-induced thrombocytopenia. Classic serum sickness is an example of a type III reaction. (See page 259: Hypersensitivity Responses: Type II Reactions.) P.53 P 10. Which of the following statements regarding intraoperative allergic reactions is/are TRUE? 1. They occur once every 5000 to 25,000 anesthetics. 2. The mortality is approximately 3.4%. 3. In anesthetized patients, the most common life-threatening manifestation of an allergic reaction is circulatory collapse. 4. Most reactions occur more than 10 minutes after an intravenous drug injection.
10. A. Intraoperative allergic reactions occur once every 5000 to 25,000 anesthetics, with a reported mortality of 3.4%. More than 90% of the allergic reactions evoked by intravenous drugs occur within 5 minutes of their administration. In anesthetized patients, the most common lifethreatening manifestation of an allergic reaction is circulatory collapse. (See page 259: Hypersensitivity Responses: Intraoperative Allergic Reactions.) 11. Which of the following statements regarding chemical mediators of inflammation is/are TRUE? 1. Leukotrienes are derived from arachidonic acid metabolism of phospholipid membranes. 2. Prostaglandins are potent mast cell mediators. 3. Prostaglandin D2 produces bronchospasm. 4. Kinins are synthesized in mast cells. 11. E. Various leukotrienes are synthesized after mast cell activation from arachidonic acid metabolism of phospholipid cell membranes via the lipoxygenase pathway. Prostaglandins are potent mast cell mediators that produce vasodilation, bronchospasm, pulmonary hypertension, and increased capillary permeability. Prostaglandin D2, the major metabolite of mast cells, produces bronchospasm and vasodilation. Kinins are synthesized in mast cells and basophils and produce vasodilation, increased capillary permeability, and bronchoconstriction. (See page 260: Anaphylactic Reactions.) 12. Which of the following statements regarding anaphylactic reactions is/are TRUE? 1. There is a more than 40% loss of intracellular fluid during anaphylactic reactions. 2. Inhalation anesthetics are the bronchodilators of choice after anaphylaxis. 3. Corticosteroids are important in attenuating the late-phase reactions that occur 1 to 2 hours after anaphylaxis. 4. Epinephrine is the drug of choice for resuscitation during anaphylactic shock.
12. D. Epinephrine, in conjunction with volume expansion, is the drug of choice during anaphylactic shock because it reverses hypotension (α adrenergic effects) and causes bronchodilation (β- 2 receptor). Inhalation anesthetics are not the bronchodilators of choice for treating bronchospasm after anaphylaxis because they interfere with the body's compensatory response to the cardiovascular collapse associated with anaphylaxis. Up to a 40% loss of intravascular fluid into the interstitial space during reactions has been reported. Corticosteroids may be important in attenuating the late-phase reactions reported to occur 12 to 24 hours after anaphylaxis. (See page 260: Anaphylactic Reactions: Treatment Plan [Initial Therapy].) 13. Which of the following statements regarding perioperative immunologic responses is/are TRUE? 1. Most anesthetic drugs and agents have been reported to produce anaphylactic reactions. 2. Muscle relaxants are the most common agents responsible for intraoperative allergic reactions. 3. Although life-threatening allergic reactions are more likely to occur in individuals with a history of allergy, atopy, or asthma, this history is not a reliable predictor whether an allergic reaction will occur. 4. There is no cross-sensitivity between succinylcholine and the nondepolarizing muscle relaxants. 13. A. Most anesthetic agents administered perioperatively have been reported to produce anaphylactic reactions. Muscle relaxants are the most common agents used that are responsible for evoking intraoperative allergic reactions. There is a cross-sensitivity between succinylcholine and the nondepolarizing muscle relaxants. Lifethreatening allergic reactions are more likely to occur in individuals with a history of allergy, atopy, or asthma but do not necessarily predict whether an allergic reaction will occur. (See page 266: Perioperative Management of the Patient with Allergies: Immunologic Mechanisms of Drug Allergy.) 14. Which of the following statements regarding latex reactions is/are TRUE?
1. There is a 24% incidence of contact dermatitis among anesthesiologists. 2. Patients with an allergy to bananas have antibodies that may cross-react to latex. 3. A history of atopy is a risk factor for latex sensitization. 4. Pretreatment always prevents anaphylaxis. 14. A. There is a 24% incidence of contact dermatitis among anesthesiologists. Patients with an allergy to bananas have antibodies that can cross-react to latex. A history of atopy is a risk factor for latex sensitization. Pretreatment can help to prevent anaphylaxis. (See page 266: Perioperative Management of the Patient with Allergies: Agents Implicated in Allergic Reactions [Latex Allergy].)
Chapter 13 Inflammation, Wound Healing and Infection 1. Which of the following is effective at removing spores? A. Alcohol-based rinses and gels B. Plain soap and water C. Iodine and iodophors D. Chlorhexidine 1. B. The most crucial component of infection prevention is frequent and effective hand hygiene. Plain (not antiseptic) soap and water are generally the least effective method of reducing hand contamination but are very effective at removing spores and therefore should be used when contamination with either Clostridium difficile or Bacillus anthracis is a concern. Alcohol-based rinses and gels denature proteins, which confers their antimicrobial activity. Alcohol-based rinses and gels are effective against bacteria and lipophilic viruses but not against spores. Iodine and iodophors penetrate the cell wall and impair protein synthesis and cell membrane function; they are effective against spore-forming bacteria but are inactive against spores. Chlorhexidine disrupts cytoplasmic membranes and is effective against gram-positive bacteria and lipophilic viruses but not against gram-negative bacteria or spore-forming organisms. (See page 272: Hand Hygiene.) 2. The majority of postoperative surgical infections are caused by flora that are: A. endogenous to the patient B. environmental contaminants C. airborne organisms D. spore-forming organisms
2. A. Most postoperative surgical infections are caused by flora that are endogenous to the patient. Environmental and airborne contaminants may also play a causative role to a lesser extent. As the number of people in the operating suite increases, the patient exposure to airborne organisms increases. Spore-forming organisms rarely contribute to postoperative surgical infections. (See page 275: Antisepsis.) 3. Which of the following statements is FALSE regarding preoperative antibiotic prophylaxis? A. Administration of antibiotics should be done within 1 hour of incision. B. Drugs that require infusion over an hour should be completed before incision. C. When a tourniquet is used, infusion must be completed before tourniquet inflation. D. Depending on half-life, antibiotics should be repeated during long operations. 3. B. Antibiotic prophylaxis has now become standard for surgeries in which there is more than a minimum risk of infection. Ideally, prophylaxis administration should be within 1 hour of incision. For drugs such as vancomycin that require infusion over an hour, it is considered acceptable if the infusion is started before incision. When a tourniquet is used, the infusion must be complete before inflation of the tourniquet. Depending on the drug's half-life, antibiotics should be repeated during long operations or operations with large blood loss. (See page 276: Antibiotic Prophylaxis.) 4. Which of the following is not an independent risk factor for methicillin-resistant Staphylococcus aureus (MRSA) infection? A. Use of drains for more than 24 hours B. Increasing number of procedures performed on the patient C. Long hospital stay D. Use of prophylactic antibiotics for more than 48 hours 4. C. Unfortunately, MRSA is becoming a more common pathogen. Independent risk factors identified for MRSA infection include prolonged
use of prophylactic antibiotics, use of drains for more than 24 hours, and increasing number of procedures performed on the patient. Long hospital stay is not an independent risk factor for MRSA infection. Hand hygiene is among the most effective means of preventing development of MRSA because when they are used properly, alcohol-based gel kills more than 99.9% of all transient pathogens, including MRSA. (See page 276: Antibiotic Prophylaxis.) 5. Which of the following is the most critical element for effective wound repair? A. Medical comorbidities B. Nutrition C. Oxygen supply to the wound D. Sympathetic nervous system activation 5. C. Many factors may impair wound healing. Systemic factors such as medical comorbidities, nutrition, sympathetic nervous system activation, and age have substantial effects on the repair process. Although all of these factors are important, perhaps the most critical element is oxygen supply to the wound. Wound hypoxia impairs all of the components of healing. (See page 277: Mechanisms of Wound Repair.) 6. Which of the following phases of wound healing is characterized by erythema and edema of the wound edges? A. Proliferation B. Remodeling C. Inflammation D. Hemostasis 6. C. Wound healing has been described in four separate phases: hemostasis, inflammation, proliferation, and remodeling. The initial response to injury is the hemostasis phase, which prevents exsanguination but also widens the area that is no longer perfused. The inflammatory phase is characterized by erythema and edema of the wound edges. The proliferative phase consists of granulation tissue formation and epithelization. The final stage of wound repair is the
maturation (and remodeling) phase. (See page 277: The Initial Response to Injury.) 7. When the wound environment becomes hypoxic and acidotic with high lactate levels, all of the following are present EXCEPT: A. decreased oxygen supply B. decreased respiratory burst activity C. increased metabolic demand D. aerobic glycolysis by inflammatory cells 7. B. In wounds, the local blood supply is compromised at the same time that metabolic demand is increased. As a result, the wound environment becomes hypoxic and acidotic with high lactate levels. This represents the sum of three effects: (1) decreased oxygen supply caused by vascular damage and coagulation, (2) increased metabolic demand caused by the heightened cellular response (anaerobic glycolysis), and (3) aerobic glycolysis by inflammatory cells. In activated neutrophils, the respiratory burst, in which oxygen and glucose are converted to superoxide, hydrogen ion, and lactate, accounts for up to 98% of oxygen consumption; in the setting of injury, this activity increases by up to 50fold over baseline. (See page 277: The Initial Response to Injury.) 8. The proliferative phase of wound healing consists of all of the following EXCEPT: A. neovascularization B. synthesis of collagen C. maturation D. epithelization 8. C. The proliferative phase normally begins approximately 4 days after injury, concurrent with a waning of the inflammatory phase. It consists of granulation tissue formation and epithelization. Granulation involves neovascularization as well as synthesis of collagen and connective tissue proteins. Maturation is the final stage of wound healing. (See page 277: Mechanisms of Wound Repair.)
9. Which of the following statements is FALSE regarding wound healing? A. The proliferative phase normally begins 4 days after injury. B. Helical configuration of collagen is primarily responsible for tissue strength. C. Local hypoxia is a normal and inevitable result of tissue injury. D. Neutrophil function does not depend on a high partial pressure of oxygen. 9. D. The proliferative phase normally begins approximately 4 days after injury. Collagen can only be exported from the cell when it is in a triple helical structure. The helical configuration is primarily responsible for tissue strength. Local hypoxia is a normal and inevitable result of tissue injury. Hypoxia acts as a stimulus to repair but also leads to poor healing and increased susceptibility to infection. The neutrophil is the primary cell responsible for nonspecific immunity, and its function depends on a high partial pressure of oxygen. (See page 277: Mechanisms of Wound Repair.) 10. Which of the following statements is FALSE about subcutaneous tissue? A. It is a reservoir used to maintain central volume. B. It is the major site of thermoregulation. C. The rate of wound infection is directly proportional to postoperative subcutaneous wound tissue oxygen tension. D. Peripheral vasoconstriction from subcutaneous vascular tone is an impediment to wound healing. 10. C. The normal subcutaneous partial pressure of oxygen, measured in test wounds in uninjured, euthermic, euvolemic volunteers breathing room, air is 65 ± 7 mm Hg. Thus, any reduction in wound partial pressure of oxygen may impair immunity and repair. In surgical patients, the rate of wound infections is inversely proportional, and collagen deposition is directly proportional to postoperative subcutaneous wound tissue oxygen tension. High oxygen tensions (>100 mm Hg) can be reached in wounds but only if perfusion is rapid and arterial PO2 is high. This is because
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subcutaneous tissue serves a reservoir function, so there is normal flow in excess of nutritional needs. Wound cells consume relatively little oxygen at a normal perfusion rate. Peripheral vasoconstriction is probably the most frequent and clinically the most important impediment to wound oxygenation. Subcutaneous tissue is both a reservoir to maintain central volume and a major site of thermoregulation. (See page 282: Wound Perfusion and Oxygenation.) 11. For an indwelling venous catheter placement, which agent is the BEST antiseptic? A. Soap B. Alcohol gels C. Iodine D. Chlorhexidine E. Ethanol 11. D. A large number of products are available for hand hygiene. The ideal agent kills a broad spectrum of bacteria and has antimicrobial activity that lasts for more than 6 hours after application. Soap and water are generally the least effective at reducing hand contamination with bacteria and are associated with an increased risk of skin irritation and drying. Alcohol-based gels denature proteins and are germicidal against bacteria and lipophilic viruses such as herpes, HIV, influenza, and hepatitis. Chlorhexidine is an antiseptic that disrupts cytoplasmic membranes and ultimately leads to precipitation of cellular components; it has substantial skin persistence, so the Centers for Disease Control and Prevention has identified it as the topical agent of choice for central venous catheter placement. It may cause corneal damage if it accidentally comes into contact with the eye, ototoxicity if it comes into contact with middle ear, and potential neurotoxicity if it comes into contact with the brain or meninges. (See page 272: Infection Control: Hand Hygiene.) 12. Which of the following statements involving antisepsis is FALSE? A. Wearing masks reduces surgical site infections. B. An increased number of operating room personnel is related to an increased incidence of infection.
C. Putting on a gown and gloves before central venous cannulation is vital to infection control. D. Masks and gowns significantly reduce the incidence of epidural abscesses. E. The use of epidural catheters is contraindicated in patients with bacteremia. 12. D. Masks are almost universally used in operating rooms; their role has long been established in protecting both patients and health care providers, especially when combined with eye protection. A recent study shows a trend toward increased postoperative infectious complications after orthopedic procedures that are associated with an increased number of personnel in the operating room; current recommended practices are that traffic patterns should limit the flow of people through operating rooms. Gowning and gloving should be routine when central venous catheterization is being used. Epidural catheter placement requires a careful aseptic technique such as hand washing, skin preparation, and draping. However, gowning and wearing masks are unlikely to reduce the risk of infection. Epidural placement should be avoided in patients suspected to have bacteremia because of an increased risk of seeding the epidural space. (See page 275: Antisepsis.) For questions 13 to 17, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 13. Which of the following factors is/are important for wound healing? 1. Aseptic technique 2. Prophylactic antibiotics 3. Perfusion of wound 4. Oxygenation of wound 13. E. Effective hand hygiene and careful surgical technique are fundamental to optimal wound healing. Antibiotic prophylaxis has become the standard for surgeries in which there is more than a minimum risk of infection. Prophylactic antibiotics are given pre- or intraoperatively. At the same time, maintaining oxygenation and
perfusion of the wound is important for wound healing. (See page 272: Hand Hygiene, Antisepsis, and Antibiotic Prophylaxis.) 14. Prolonging the course of prophylactic antibiotics for more than 24 hours increases the risk of which of the following? 1. Antibiotic resistance 2. Clostridium difficile infection 3. Sensitization 4. Effectiveness against infection 14. A. Prophylactic antibiotics are given pre- or intraoperatively. They should be discontinued by 24 hours after surgery. Prolonging the course of prophylactic antibiotics does not reduce the risk of infection but does increase the risk of adverse consequences of antibiotic administration, including resistance, Clostridium difficile infection, and sensitization. (See page 276: Antibiotic Prophylaxis.) 15. Oxygen plays an important role in which of the following physiologic processes? 1. Wound healing 2. Aerobic respiration 3. Oxidative phosphorylation 4. Leukocyte mediated bacterial killing and collagen formation 15. E. Oxygen plays a key role in aerobic respiration and energy production via oxidative phosphorylation. In wound healing, oxygen is required as a cofactor for enzymatic processes and for cell-signaling mechanisms. Oxygen is a rate-limiting component in leukocyte-mediated bacterial killing and collagen formation because specific enzymes require oxygen at a partial pressure of at least 40 mm Hg. (See page 277: Mechanisms of Wound Repair.) 16. Which of the following factors have shown to decrease wound infections in patients undergoing major abdominal surgery? 1. Prevention or correction of hypothermia 2. Providing supplemental oxygen postoperatively
3. Prevention or correction of blood volume deficit 4. Use of high inspired oxygen intraoperatively 16. E. Prevention and correction of hypothermia and blood volume deficits have been shown to decrease wound infections and increase collagen deposition in patients undergoing major abdominal surgery. Preoperative systemic or local warming has also been shown to decrease wound infections, even in clean, low-risk surgeries. The preponderance of evidence indicates that use of high inspired oxygen intraoperatively and providing supplemental oxygen postoperatively in well-perfused patients undergoing major abdominal surgery will reduce the risk of wound infection. (See page 282: Wound Perfusion and Oxygenation.) 17. Wound oxygen delivery depends on which of the following factors? 1. Vascular anatomy 2. Degree of vasoconstriction 3. Arterial PO2 4. Hemoglobin-bound oxygen 17. A. Normally, wounds on the extremities and trunk heal more slowly than those on the face. The major difference in these wounds is the degree of tissue perfusion and thus the wound tissue oxygen tension. Wound oxygen delivery depends on the vascular anatomy, the degree of vasoconstriction, and arterial PO2. The standard teaching that oxygen delivery depends more on hemoglobin-bound oxygen than on arterial PO2 may be true of working muscle but is not true for wound healing. In muscle, intercapillary distances are small, and oxygen consumption is high. In contrast, intercapillary distances are large, and oxygen consumption is relatively low in subcutaneous tissue. In wounds, where the microvasculature is damaged, diffusion distances are substantially increased. Peripheral vasoconstriction further increases diffusion distance. The driving force of diffusion is partial pressure. Resistance to infection is critically impaired by wound hypoxia and becomes more efficient as partial pressure of oxygen increases to very high levels. This is one mechanism for the proposed benefit of hyperbaric oxygen therapy as an adjunctive treatment for necrotizing infections and chronic
refractory osteomyelitis. (See page 282: Wound Perfusion and Oxygenation.)
Chapter 14 Fluids, Electrolytes, and Acid Base Physiology 1. A previously healthy patient acutely develops metabolic alkalosis resulting from intravenous diuretic administration. The measured HCO3 is 36 mEq/L. The arterial blood gas analysis shows: A. pH, 7.51; PaCO2, 47; PO2, 90 B. pH, 7.42; PaCO2, 52; PO2, 90 C. pH, 7.51; PaCO2, 47; PO2, 110 D. pH, 7.61; PaCO2, 52; PO2, 90 E. pH, 7.51; PaCO2, 40; PO2, 100 1. A. This represents metabolic alkalosis with partial respiratory compensation. The rules of thumb for calculating the expected response to metabolic alkalosis are as follows: (1) PaCO2 increases approximately 0.5 to 0.6 mm Hg for each 1.0-mEq/L increase in HCO3 and (2) the last two digits of the pH should equal the HCO3 + 15. Hypercarbia is accompanied by a reduced PaO2 as given by the alveolar gas equation. (See page 291: Metabolic Alkalosis and page 292: Table 14-3.) 2. Metabolic acidosis with a normal anion gap may be caused by: A. Aspirin toxicity B. Diabetic ketoacidosis C. Chronic diarrhea D. Uremia E. Lactic acidosis 2. C. Metabolic acidosis may be characterized by a high anion gap or a normal anion gap. Metabolic acidosis with a high anion gap results from
excess anions such as lactate, ketoacetate, sulfate, salicylate, and other toxic compounds. Metabolic acidosis with a normal anion gap is caused by loss of HCO3 resulting from diarrhea, biliary drainage, or renal tubular acidosis. (See page 292: Metabolic Acidosis and page 292: Table 14-4.) 3. What is the best interpretation of an arterial blood gas analysis of pH, 7.35; PaCO2, 60; PO2, 80; and HCO3, 32? A. Acute respiratory acidosis B. Chronic respiratory acidosis with metabolic compensation C. Chronic respiratory acidosis without metabolic compensation D. Chronic metabolic alkalosis with respiratory compensation E. Acute metabolic alkalosis 3. B. The pH below 7.40 suggests acidosis as the primary event, and the PaCO2 of 60 shows that this patient has respiratory acidosis. The appropriate chronic metabolic compensation is that HCO3 increases 4 mEq/L for each 10-mm Hg increase in PaCO2, thus bringing the HCO3 to 32 mEq/L. The pH will return toward normal. (See page 294: Practical Approach to Acid-Base Interpretation.) 4. What is the best interpretation of an arterial blood gas analysis of pH, 7.24; PaCO2, 60; PO2, 80; and HCO3, 26? A. Acute respiratory acidosis B. Chronic respiratory acidosis with appropriate metabolic compensation C. Chronic respiratory acidosis with inappropriate metabolic compensation D. Chronic metabolic alkalosis with respiratory compensation E. Acute metabolic alkalosis 4. A. The pH 7.24 suggests acidosis as the primary event, and the PaCO2 of 60 shows that this patient has respiratory acidosis. (See page 294: Practical Approach to Acid-Base Interpretation.)
5. What is the best interpretation of an arterial blood gas analysis of pH, 7.50; PaCO2, 30; PO2, 110; and HCO3, 22? A. Acute respiratory alkalosis B. Chronic respiratory alkalosis with metabolic compensation C. Acute metabolic acidosis with respiratory compensation D. Chronic metabolic alkalosis with respiratory compensation E. Chronic metabolic acidosis 5. A. The pH of 7.50 suggests alkalosis as the primary event, and the PaCO2 of 30 shows that this patient has respiratory alkalosis. (See page 294: Practical Approach to Acid-Base Interpretation.) 6. Total body water is approximately _________ % of total body weight. A. 10 B. 20 C. 40 D. 60 E. 80 6. D. Total body water (in liters) is equal to approximately 60% of total body weight (in kilograms). The intracellular volume constitutes 40% of total body weight, and the extracellular volume constitutes 20% of body weight. (See page 296: Body Fluid Compartments.) 7. Intracellular volume (ICV) is _________ % of total body weight. A. 10 B. 20 C. 40 D. 60 E. 80 7. C. Total body water consists of ICV, which constitutes 40% of total body weight (28 L in a 70-kg person), and extracellular volume, which
constitutes 20% of body weight (14 L). (See page 296: Body Fluid Compartments.) 8. Plasma volume is approximately _________ % of the extracellular volume (ECV). A. 10 B. 20 C. 30 D. 40 E. 50 8. B. Plasma volume, approximately 3 L, equals about one fifth (20%) of the ECV. The remainder of the ECV is interstitial fluid. Red blood cell (RBC) volume, approximately 2 L, is part of the intracellular volume. Total blood volume is approximately 5 L (3 L of plasma + 2 L of RBC mass). (See page 296: Body Fluid Compartments.) 9. The extracellular concentrations of sodium (Na) is approximately _________ mEq/L. A. 150 B. 130 C. 140 D. 120 E. 110 9. C. The extracellular fluid contains most of the Na in the body, with equal Na concentrations (∼140 mEq/L) in the plasma and interstitium. (See page 296: Body Fluid Compartments.) 10. The intracellular concentration of potassium (K) is approximately _________ mEq/L. A. 110 B. 130 C. 150 D. 4
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E. 10 10. C. The predominant intracellular cation is K+, with an intracellular concentration of approximately 150 mEq/L. (See page 296: Body Fluid Compartments.) 11. An acute blood loss of 2000 mL represents _________ % of the predicted blood volume in a previously healthy 70-kg man. A. 10 B. 20 C. 30 D. 40 E. 50 11. D. A 2000-mL blood loss represents approximately 40% of the predicted 5-L blood volume in a previously healthy 70-kg patient. The normal blood volume is approximately 70 mL/kg; the normal plasma volume is three fifths of this value, or approximately 3 L. (See page 296: Body Fluid Compartments.) 12. To achieve a more than transient 2000-mL restoration of plasma volume (PV) would require infusion of _________ mL of D5W solution. A. 2000 B. 4500 C. 7000 D. 14,000 E. 28,000 12. E. The volume that is to be infused to achieve a 2-L increase in PV is equal to Expected PV increment × Distribution volume of infusate/Normal PV. The normal PV is 3 L; the distribution volume for D5W is the total body water, which is 42 L (60% of 70 kg). Hence, the equation becomes: 2 L × 42 L/3 L = 28 L. To achieve a 2-L increase in overall intravascular volume, 28 L of D5W would theoretically be required. (See page 296: Body Fluid Compartments.)
13. To achieve a more than transient 2-L restoration of plasma volume using lactated Ringer's solution would require infusion of approximately _________ L. A. 10 B. 15 C. 30 D. 45 E. 50 13. A. The distribution volume for lactated Ringer's solution is the extracellular fluid, which is 14 L (20% of 70 kg). Hence, the equation for plasma expansion becomes 2 L × 14 L/3 L = 9.3 L. (See page 296: Distribution of Infused Fluids.) 14. To achieve a more than transient 2-L restoration of plasma volume using 5% albumin would require infusion of _________ L. A. 1 B. 2 C. 5 D. 7 E. 10 14. B. The distribution volume of 5% albumin is approximately equal to that of the plasma. Hence, the replacement volume would be equal to the volume lost. (See page 296: Distribution of Infused Fluids.) 15. To achieve a more than transient 2-L restoration of plasma volume using 6% hetastarch would require infusion of _________ L. A. 1 B. 2 C. 5 D. 7 E. 10
15. B. The distribution volume of 6% hetastarch is approximately equal to that of the plasma. Hence, the replacement volume would be equal to the volume lost. (See page 296: Distribution of Infused Fluids.) 16. Chronic gastric losses tend to cause: A. hypochloremic alkalosis B. hyperchloremic alkalosis C. hypochloremic acidosis D. hyperchloremic acidosis E. alkalosis with a normal chloride value 16. A. Chronic gastric losses tend to produce hypochloremic metabolic alkalosis; potassium may also be lost. (See page 299: Surgical Fluid Requirements.) 17. Chronic diarrhea tends to produce: A. hypochloremic acidosis B. hyperchloremic alkalosis C. hyperchloremic acidosis D. hyperchloremic alkalosis E. alkalosis with a normal chloride value 17. C. Chronic diarrhea may produce hyperchloremic metabolic acidosis. (See page 299: Surgical Fluid Requirements.) 18. What is the osmolality (mOsm/kg) of plasma that contains 140 mEq/L of Na, 90 mg/dL of glucose, and a blood urea nitrogen (BUN) of 11.5 mg/dL? A. 280 B. 290 C. 300 D. 310 E. 320
18. B. The osmotic activity of body fluids represents the number of osmotically active particles per kilogram of solvent. It is conventionally reported as osmolality (mmol/kg) and can be estimated as follows: Osmolality = Na+ × 2 + (Glucose/18) + (BUN/2.3), where Na+ is expressed in mEq/L and serum glucose and BUN is expressed in mg/dL. Hence, plasma, which contains 140 mEq/L of Na+, 90 mg/dL of glucose, and a BUN of 11.5 mg/L, has 280 + 5 + 5 for a total of 290 mmol/kg. The Na+ is doubled to account for “matching” anions (e.g., Cl). (See page 301: Colloids, Crystalloids, and Hypertonic Solutions.) 19. Which of the following formulas accurately expresses Starling law of capillary filtration? A. Q = kA[(Pc - Pi) + k(πi - πc)] B. Q = kA[(Pc - Pi) - k(πi - πc)] C. Q = kA[(Pc - Pi) - σ (πi - πc)] D. Q = kA[(Pc - Pi) + σ (πi - πc)] E. Q = kA[(Pc - Pi) + (πi - πc)] 19. D. The filtration rate of fluid from the capillaries into the interstitial space is the net result of a combination of forces, including the gradient between intravascular and interstitial hydrostatic pressures and the gradient between interstitial and intravascular colloid oncotic pressures. The net filtration from capillary to interstitium may be expressed by the following equation: Q = kA [(Pc - Pi)+ σ (πi - πc)], where Q is fluid filtration, k is the capillary filtration coefficient (conductivity of water), A is the area of the capillary membrane, Pc - Pi is the difference between capillary and interstitial hydrostatic pressures, and πi - πc is the difference between interstitial and capillary oncotic pressures. The reflection coefficient (σ) describes the permeability of capillary membranes to individual solutes. (See page 301: Colloids, Crystalloids, and Hypertonic Solutions.) 20. Which of the following is NOT a typical finding during hypovolemia? A. Blood urea nitgrogen (BUN) >20 mg/dL
B. BUN/serum creatinine >20 mg/dL C. Urinary Na 400 mOsm/kg E. Serum/urine creatinine ratio >1:40 20. E. If the ratio of BUN to serum creatinine exceeds the normal range (10–20 mg/dL), one should suspect dehydration or one of the individual factors that alters the serum concentration of the two metabolites. In prerenal oliguria, enhanced Na reabsorption should reduce urinary Na to below 20 mEq/L, and enhanced water reabsorption should increase urinary concentration (i.e., urinary osmolality >400 mOsm/kg; urine/plasma creatinine ratio >40:1). (See page 303: Assessment of Hypovolemia and Tissue Hypoperfusion.) 21. What is the typical daily fluid requirement for a 30-kg child? A. 300 mL B. 3000 mL C. 1100 mL D. 1400 mL E. 1700 mL 21. E. Typical maintenance requirements may be calculated according to formulas for hourly or daily administration. For the first 10 kg of weight, 4 mL/kg/hr or 100 mL/kg/day should be administered. For the eleventh to twentieth kg, 2 mL/kg/hr or 50 mL/kg/day should be given. For each additional kilogram, 1 mL/kg/hr or 20 mL/kg per day should be administered. Thus, a 30-kg child should receive 1000 mL + 500 mL + 200 mL = 1700 mL. (See page 299: Fluid Replacement Therapy and page 299: Table 14-10.) 22. Which of the following statements concerning Na regulation is FALSE? A. Aldosterone promotes reabsorption of Na in the kidney. B. Aldosterone promotes exchange of Na for potassium and hydrogen.
C. Stretching of the atria promotes release of atrial natriuretic peptide. D. Antidiuretic hormone (ADH) affects serum Na concentration. E. Excess ADH results in increased free water excretion. 22. E. Increased secretion of ADH results in reabsorption of water by the kidneys and subsequent dilution of the plasma Na+; inadequate ADH secretion results in renal free water excretion that, in the absence of adequate water intake, results in hypernatremia. Total body Na is also regulated by aldosterone, which is responsible for renal Na reabsorption in exchange for potassium and hydrogen. Alternatively, stretching of the cardiac atria causes secretion of atrial natriuretic peptide, which increases renal Na excretion. (See page 304: Sodium.) For questions 23 to 41, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. P 23. Physiologic consequences of metabolic alkalosis include: 1. rightward shift of the oxyhemoglobin dissociation curve 2. hyperkalemia 3. hypercalcemia 4. hypercarbia 23. D. Metabolic alkalosis is associated with decreased serum potassium and ionized calcium. There is a compensatory respiratory acidosis, leading to hypercarbia. The oxyhemoglobin curve is shifted to the left, impairing oxygen delivery to tissues. Bronchial tone is increased and may lead to atelectasis. (See page 291: Metabolic Alkalosis.) 24. TRUE statements concerning the treatment of metabolic acidosis with HCO3 include: 1. It improves cardiovascular response to catecholamines. 2. It is clearly effective in improving outcome. 3. The appropriate dose is 0.7 × (Body weight in kg) (24 - HCO3).
4. It reduces plasma ionized calcium. 24. D. Although many clinicians administer NaHCO3 to patients with persistent lactic acidosis, there is little evidence that it is efficacious or improves outcome. NaHCO3 does not improve cardiovascular response to catecholamines and reduces plasma ionized calcium. The initial dose of HCO3 may be calculated as:
where 0.3 is the assumed distribution space of the HCO3. (See page 291: Metabolic Acidosis.) 25. Respiratory alkalosis and metabolic alkalosis both: 1. produce hypokalemia 2. decrease cerebral blood flow 3. potentiate digoxin toxicity 4. may be appropriately treated with HCl 25. B. Regardless of its origin, alkalosis may produce hypokalemia, hypocalcemia, cardiac dysrhythmias, bronchoconstriction, and hypotension and may potentiate the toxicity of digoxin. Cerebral blood flow is reduced by acute hypocapnia; metabolic alkalosis may be compensated by hypercapnia, causing increased cerebral blood flow. Only metabolic alkalosis may be appropriately treated with an acid. (See page 293: Respiratory Alkalosis.) 26. Renal adaptation to hypovolemia and decreased cardiac output includes: 1. decreased renal vascular resistance 2. redistribution of blood flow from outer cortical to inner cortical nephrons 3. increased reabsorption of water and Na resulting from increased atrial natriuretic hormone 4. increased reabsorption of water from the medullary collecting ducts
26. C. The renal response to hypovolemia and decreased cardiac output is to increase renal vascular resistance and decrease the loss of Na and water. Blood is redistributed to the inner cortical nephrons, which have longer loops of Henle that penetrate more deeply into the hypertonic renal medulla. Increased antidiuretic hormone (ADH) release promotes water reabsorption through medullary collecting ducts and cortical collecting tubules. Aldosterone promotes Na reabsorption, primarily in the distal tubules. The response to hypovolemia also includes suppression of the release of atrial natriuretic hormone. The increased release of renin promotes conversion of angiotensinogen to angiotensin I. (See page 297: Regulation of Extracellular Fluid Volume.) 27. TRUE statements concerning fluid resuscitation and the brain include: 1. The cerebral capillary membrane is highly impermeable to protein. 2. Hyperglycemia may aggravate ischemic brain injuries. 3. Normal saline is superior to lactated Ringer's solution in the context of brain injury. 4. Cerebral edema is an early sign of reduced plasma protein. 27. A. The osmolality of replacement fluid is very important in the presence of brain injury. Lactated Ringer's solution is slightly hypoosmotic relative to serum and thus may be associated with increased cortical water content. Hypertonic solutions may exert favorable effects on cerebral hemodynamics. The benefit usually is transient, and hypertonic therapy may be associated with complications, including subdural hematoma. The cerebral capillary membrane (the blood–brain barrier) is highly impermeable to protein, and oncotic pressure exerts little, if any, effect on brain water accumulation. Hyperglycemia may aggravate ischemic brain injury. (See page 302: Implications of Crystalloid and Colloid Infusions on Intracranial Pressure.) 28. Which of the following statements concerning abnormal Na+ concentrations is/are TRUE? 1. A decrease in plasma Na+ leads to a decrease in intracellular brain water.
2. Hyponatremia may result from inappropriate antidiuretic hormone (ADH) secretion. 3. Mannitol may result in hypernatremia in the presence of a high serum osmolality. 4. Absorption of irrigant solution during transurethral resection of the prostate may result in hyponatremia in the presence of a high serum osmolality. 28. C. Although the blood–brain barrier is poorly permeable to Na, water equilibrates rapidly. Thus, acute hyponatremia causes a prompt increase in intracellular brain water. An acute lowering of serum Na+ concentration may be induced by mannitol, sorbitol, and other non-Na solutes, which do not diffuse freely across cell membranes and may cause an increase in extracellular volume. Hyponatremia likewise may result from high levels of ADH. (See page 304: Sodium.) 29. TRUE statements concerning hypermagnesemia include: 1. The therapeutic range for treatment of pre-eclampsia is between 15 and 18 mg/dL. 2. Heart block commonly is noted at 18 mg/dL. 3. Hypotension is not noted until concentrations are 13 mg/dL. 4. Areflexia often is noted by 12 mg/dL. 29. C. Normal serum Mg2+ ranges between 1.8 and 2.4 mg/dL (0.8–1.2 mmol/L; 1.6–2.4 mEq/L). The therapeutic range for treatment of preeclampsia is between 5 and 8 mg/dL. Symptoms that develop above 3 mg/dL: hypotension (>3 mg/dL), hyporeflexia (>5 mg/dL), somnolence (>8.5 mg/dL), areflexia and respiratory insufficiency (>12 mg/dL), heart block and respiratory paralysis (>18 mg/dL), and cardiac arrest (>24 mg/dL). (See page 320: Magnesium and page 321: Table 14-23.) 30. Which of the following statements concerning diabetes insipidus is/are TRUE? 1. It is more common after pituitary surgery. 2. Central diabetes insipidus is exacerbated by desmopressin.
3. In nephrogenic diabetes insipidus, the collecting ducts are resistant to antidiuretic hormone (ADH). 4. It often results in hyponatremia. 30. B. Diabetes insipidus is associated with a loss of free water. It may be central in origin, with decreased ADH secretion; this has an increased incidence after pituitary surgery. It may also be peripheral in origin (nephrogenic), with the collecting ducts being resistant to ADH. Both the central and peripheral forms lead to hypernatremia. Treatments include water replacement, desmopressin (DDAVP), vasopressin, and drugs that stimulate ADH release (chlorpropamide, clofibrate, thiazide diuretics). (See page 304: Sodium.) 31. Which of the following statements concerning regulation of serum potassium levels is/are TRUE? 1. Aldosterone increases potassium excretion. 2. Potassium excretion is increased in the presence of nonreabsorbable anions in the renal luminal fluid. 3. Insulin causes an intracellular shift of potassium. 4. Epinephrine and exogenous β 2-agonists cause an extracellular shift of potassium. 31. A. Aldosterone increases renal reabsorption of Na+ and excretion of K+. Renal excretion of K+ is also increased by high urinary flow rates and the presence in the renal tubular fluid of nonreabsorbable anions such as carbenicillin and phosphates. An intracellular shift of K+ is caused by insulin, alkalosis, and β 2-agonists. (See page 311: Potassium.) 32. Which of the following statements concerning hypokalemia is/are TRUE? 1. The ratio of intracellular to extracellular potassium remains relatively stable with chronic potassium loss. 2. As a general rule, a decrease of 1.0 mEq/L represents a total body deficit of 200 to 300 mEq. 3. Both metabolic and respiratory alkalosis lead to decreases in plasma potassium concentration.
4. Hypothermia may cause acute hypokalemia. 32. E. Chronic potassium loss that causes a 1.0-mEq/L decrease of plasma K+ is typically associated with a total body deficit of 200 to 300 mEq. However, in contrast to the hyperpolarization that accompanies an acute loss, the ratio of intracellular to extracellular K+ remains relatively stable during a chronic loss. An intracellular shift of K+ (and hypokalemia) may accompany respiratory and metabolic alkalosis and severe hypothermia; the changes resolve upon correction of alkalosis and rewarming. (See page 311: Potassium.) 33. Changes associated with hypokalemia include: 1. hyperpolarization of cardiac cells 2. ST segment depression 3. re-entrant arrhythmias 4. exacerbation of digitalis toxicity 33. E. Acute hypokalemia causes hyperpolarization of the cardiac cell, which may lead to ventricular escape activity, re-entrant arrhythmias, and delayed conduction, with potentiation of digitalis-induced effects. Common signs include first-degree atrioventricular block and ST segment depression. (See page 311: Potassium.) 34. Which of the following statements concerning hyperkalemia is/are TRUE? 1. It may be treated with triamterene. 2. It may result from mineralocorticoid deficiency. 3. It may be treated with angiotensin-converting enzyme (ACE) inhibitors. 4. Furosemide promotes kaliuresis. 34. C. A mineralocorticoid deficiency may lead to hyperkalemia. Likewise, administration of a drug (e.g., ACE inhibitor) that reduces the release of aldosterone or opposes the effects of aldosterone (e.g., triamterene or spironolactone) causes an increase in K+ levels. These effects may be offset by a drug that promotes kaliuresis (e.g.,
furosemide). They may also be treated with mineralocorticoid supplementation. (See page 311: Potassium.) P 35. Effects of hyperkalemia include: 1. tall, peaked T waves 2. shortened P-R interval 3. widened QRS complex 4. peaked P waves 35. B. With progressive hyperkalemia, the electrocardiogram shows tall, peaked T waves followed by a prolonged P-R interval and then a decrease in P-wave height. These changes may progress to widening of the QRS complex and asystole. The effects are exacerbated by hyponatremia, hypocalcemia, acidosis, and digitalis toxicity. (See page 311: Potassium.) 36. Symptomatic hyperkalemia may be treated with: 1. calcium chloride 2. NaHCO3 3. regular insulin 4. β 2-agonists 36. E. Serum K+ concentrations may be acutely lowered by administration of NaHCO3 (50–100 mEq), 5 to 10 U of regular insulin administered intravenously with 50 mL of 50% glucose, β 2-adrenergic agonists, or furosemide (or related diuretics). Acute therapy may also include calcium chloride, which depresses the membrane threshold potential. More delayed forms of therapy include Na polystyrene sulfonate resin (Kayexalate) exchanges. (See page 311: Potassium.) 37. TRUE statements about ionized calcium include: 1. The ionized calcium concentration in the extracellular fluid (ECF) is approximately 1.0 mM.
2. Its concentration is increased by increased parathyroid hormone activity. 3. Its concentration may be decreased by hyperphosphatemia. 4. Its concentration is decreased by acidemia. 37. A. The concentration of free calcium in the ECF is normally 1 to 1.25 mM. Because calcium is divalent, this corresponds to 2.0 to 2.5 mEq/L. The remaining 50% of extracellular calcium is protein bound (40%) or chelated (10%). Parathyroid hormone helps regulate the concentration of the physiologically active (ionized) form and increases plasma calcium levels. Calcium may be lowered by increased phosphate. Hyperphosphatemic hypocalcemia results from calcium precipitation and suppression of calcitriol synthesis. Whereas acute acidemia decreases protein-bound calcium (i.e., increases ionized calcium), acute alkalemia increases protein-bound calcium (i.e., decreases ionized calcium). (See page 314: Calcium.) 38. TRUE statements concerning hypocalcemia include: 1. It may cause increased sensitivity to digitalis. 2. It does not necessarily occur after transfusion, even if 5 U of blood is infused within 1 hour. 3. It may cause Q-T shortening. 4. It may cause laryngeal spasm. 38. C. Hypocalcemia causes increased neuronal membrane irritability and tetany, as demonstrated by eliciting the Chvostek or Trousseau sign. It causes Q-T and ST prolongation, T-wave inversion, and insensitivity to digitalis. Hypocalcemia may cause laryngeal spasm after parathyroid removal. In massive transfusion, citrate may produce hypocalcemia by chelating calcium. However, a healthy, normothermic adult with intact hepatic and renal function can adequately metabolize the citrate provided (without becoming hypocalcemic) when 5 U of blood is infused in 1 hour. When citrate clearance is decreased or when blood transfusion rates are rapid (e.g., 0.5–2 mL/kg/min), severe hypocalcemia can occur. (See page 314: Calcium.) 39. TRUE statements about hypercalcemia include:
1. Severe symptoms are generally noted when the total serum calcium concentration is above 13 mg/dL. 2. Symptoms include lethargy, anorexia, nausea, and polyuria. 3. Cardiovascular effects include hypertension, heart block, and cardiac arrest. 4. A patient with hypercalcemia typically is helped by infusion of NaCl. 39. E. Patients with moderate hypercalcemia (total serum calcium, 11.5–13 mg/dL) may show symptoms of lethargy, anorexia, nausea, and polyuria. Severe hypercalcemia (total serum calcium >13 mg/dL) is associated with severe neuromyopathic symptoms (including muscle weakness, depression, impaired memory, emotional lability, lethargy, stupor, and coma), renal calcium salt precipitation (nephrocalcinosis), and cardiovascular changes (hypertension, arrhythmias, heart block, cardiac arrest, and digitalis sensitivity). General supportive treatment includes hydration, correction of associated electrolyte abnormalities, removal of offending drugs, and dietary calcium restriction. Infusion of 0.9% saline will dilute serum calcium, reverse Na and water depletion, and promote renal excretion. Other treatments include calcitonin, mithramycin, and etidronate disodium (a diphosphonate). (See page 314: Calcium.) 40. TRUE statements about altered phosphate concentrations include: 1. High concentrations promote deposition of calcium in the bone, soft tissues, and kidneys. 2. Hypophosphatemia leads to muscle weakness, which may lead to decreased ventilatory strength. 3. The serum concentration of phosphate decreases in response to acute alkalemia. 4. Rapid administration of phosphate to a patient with hypocalcemia may precipitate more severe hypocalcemia. 40. E. The clinical features of hyperphosphatemia relate primarily to the development of hypocalcemia and ectopic calcification. Hyperphosphatemia can promote calcification in vital organs such as the
kidneys and myocardium. Neurologic manifestations of hypophosphatemia include paresthesias, encephalopathy, delirium, seizures, and coma. Hematologic abnormalities include dysfunction of erythrocytes, platelets, and leukocytes. Muscle changes include myopathies, with respiratory muscle failure and myocardial dysfunction. Phosphate should be administered cautiously to hypocalcemic patients because of the risk of precipitating more severe hypocalcemia. (See page 319: Phosphate.) 41. TRUE statements concerning hypomagnesemia include: 1. Symptoms generally develop when the serum magnesium (Mg2+) concentration is below 1.0 mg/dL. 2. It predisposes to digitalis toxicity. 3. Rapid correction of hypermagnesemia may cause symptoms consistent with hypocalcemia. 4. It predisposes to coronary artery spasm. 41. E. Normal Mg2+ levels in the plasma are approximately 1.7 mg/dL. Symptoms of hypomagnesemia occur at levels below 1.0 mg/dL. The clinical features of hypomagnesemia, similar to those of hypocalcemia, are characterized by increased neuronal irritability, tetany, weakness, lethargy, muscle spasms, paresthesias, and depression. Severe hypomagnesemia may induce cardiovascular abnormalities, including coronary artery spasm, cardiac failure, dysrhythmias, hypotension, and increased myocardial sensitivity to digitalis. Rapid correction of hypomagnesemia may cause symptoms consistent with hypocalcemia. (See page 320: Magnesium.)
Chapter 15 Autonomic Nervous System 1. Which of the following statements concerning the sympathetic nervous system (SNS) is TRUE? A. The preganglionic fibers originate in the gray column of the two lower cervical, 12 thoracic, and first lumbar segments of the spinal cord. B. There are 22 paired sympathetic ganglia. C. Preganglionic fibers only synapse with postganglionic fibers in ganglia at the level of exit. D. Preganglionic fibers may also synapse in a ganglion that can then traverse to the adrenal gland. E. All preganglionic fibers are unmyelinated fibers. 1. B. The preganglionic fibers originate from T1–T12 and L1–L3 in the gray intermediolateral column. These fibers are myelinated nerve axons that leave the spinal cord with the motor fibers to form the white communicating rami. These fibers enter the 22 paired sympathetic ganglia. After entering these ganglia, the fibers may take three possible courses: they may synapse with postganglionic fibers in the ganglion, they may move up and down the SNS to another ganglion, or they may track through the sympathetic chain and exit without synapsing to SNS collateral ganglia. The exception to this rule is the group of myelinated fibers that terminate in the adrenal medulla without first synapsing in a ganglion. Many of the postganglionic fibers pass from the lateral SNS chain back into the spinal nerves to form the gray (unmyelinated) communicating rami at all levels of the spinal cord. They are distributed distally to the sweat glands, pilomotor muscle, and blood vessels of the skin and muscle. (See page 329: Sympathetic Nervous System or Thoracolumbar Division.) 2. Which of the following statements concerning postganglionic fibers of the sympathetic nervous system (SNS) is TRUE?
A. The postganglionic nerve cell bodies are located only in the paired lateral ganglia. B. The celiac and inferior mesenteric ganglia are located along the spinal cord and are considered part of a sympathetic paired ganglion. C. All ganglia of the sympathetic chain are located closer to the spinal cord than the organs they innervate. D. Postganglionic myelinated fibers proceed from paired ganglia to the respective organs. E. Approximately 25% of the fibers in the average somatic nerve are sympathetic. 2. C. Postganglionic neuronal cell bodies of the SNS are located in the paired lateral ganglia or unpaired collateral ganglia. The celiac and inferior mesenteric ganglia are considered to be collateral ganglia. SNS ganglia are located primarily near the spinal cord rather than near the organs they innervate. The postganglionic fibers are unmyelinated. The average somatic nerve has approximately 8% sympathetic fibers. (See page 329: Sympathetic Nervous System or Thoracolumbar Division.) 3. Which of the following statements concerning the sympathetic nervous system (SNS) is TRUE? A. The first four to five thoracic spinal segments generate fibers that converge to form three special paired ganglia. B. The middle cervical ganglion also is known as the stellate ganglion. C. The stellate ganglion provides sympathetic innervation only to the head and neck. D. The response of the SNS is very discrete. E. One preganglionic fiber influences one postganglionic neuron. 3. A. The first four to five thoracic segments' preganglionic fibers form three specialized paired ganglia: the superior cervical, middle cervical, and cervicothoracic ganglia. The latter is known as the stellate ganglion. It is a fusion of the inferior cervical and first thoracic SNS ganglia. This provides sympathetic innervation to the head, neck, upper extremities,
heart, and lungs. The response from sympathetic system activation is diffuse. The preganglionic neurons are fewer than the postganglionic neurons. Hence, preganglionic fibers influence a number of postganglionic neurons. (See page 329: Sympathetic Nervous System or Thoracolumbar Division.) 4. Which of the following statements regarding the parasympathetic nervous system (PNS) is TRUE? A. The sacral fibers originate from the white matter of the second, third, and fourth sacral nerves. B. Preganglionic fibers are myelinated fibers analogous to those in the sympathetic nervous system (SNS) and terminate in ganglia next to the spinal cord. C. The ratio of preganglionic to postganglionic fibers in the PNS is the same as in the SNS. D. Postganglionic neurons are located in or near the organ to be innervated. E. Cranial nerve X has the least innervation of all PNS nerves. 4. D. The PNS consists of preganglionic and postganglionic neurons. The preganglionic nerve fibers originate in cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus) nerves. In addition, fibers originate from the intermediolateral horn of the second, third, and fourth sacral nerves. Preganglionic nerve fibers pass directly to the organ that is innervated. Postganglionic neurons are located in or near the organ to be innervated. Therefore, postganglionic innervation is limited, and responses are discrete. Cranial nerve X (vagus) accounts for 75% of the PNS activity. The ratio of postganglionic to preganglionic fibers in many organs appears to be 1:1 to 3:1 compared with the 20:1 found in the SNS system. (See page 330: Parasympathetic Nervous System or Craniosacral Division.) 5. All of the following are functions of the autonomic innervation of the heart EXCEPT: A. The autonomic nervous system (ANS) changes the heart rate (chronotropism). B. The ANS changes the strength of contraction (inotropism).
C. The ANS modulates coronary blood flow. D. There is parasympathetic innervation of the ventricles of the heart. E. The vagus affects the sinoatrial (SA) and atrioventricular (AV) nodes. 5. D. The heart is well supplied by both the SNS and parasympathetic nervous system (PNS). These fibers are responsible for changing the rate of the heart (chronotropism), changing the strength of contraction (inotropism), and modulating coronary blood flow. PNS innervation is to the SA and AV nodes. There is no PNS supply to the ventricles. (See page 330: Autonomic Innervation: Heart.) 6. Which of the following statements regarding the autonomic nervous system (ANS) and peripheral circulation is TRUE? A. The sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) are equally distributed in the peripheral circulation. B. Distribution is equal among all tissues. C. SNS stimulation of the coronary arteries may produce vasoconstriction or vasodilation, depending on the predominant receptor activity. D. Vascular tone is predominantly controlled by PNS activity. E. Local autoregulatory factors do not influence coronary vascular tone. 6. C. The SNS is the predominant regulator of the peripheral circulation; PNS innervation is minimal. The SNS may cause vasodilation or vasoconstriction, depending on receptor activity. Distribution of the SNS is not equal among all organs. The skin, kidneys, spleen, and mesentery have extensive SNS distribution; the heart, brain, and muscles have less. Vascular tone is highly influenced by local factors such as metabolites and hormones. Blood vessels have differing sensitivities to local or neurogenic tone. Local autoregulation is predominantly at the precapillary and postcapillary sphincters. (See page 331: Peripheral Circulation.)
7. All of the following statements about neurotransmission in the autonomic nervous system (ANS) are true EXCEPT: A. The sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) are commonly designated as adrenergic and cholinergic, respectively. B. In the PNS, the postganglionic receptors secrete acetylcholine (Ach). C. Norepinephrine is the only neurotransmitter of the SNS at the postganglionic site. D. The preganglionic neurotransmitter is Ach in both the PNS and the SNS. E. Terminations of postganglionic fibers are anatomically and physiologically similar in both the SNS and PNS. 7. C. The SNS and PNS are designated as adrenergic and cholinergic, respectively. In the PNS, Ach is secreted at the postganglionic receptor site. In the SNS, norepinephrine is the main neurotransmitter at postganglionic sites, with the exception of sweat glands. The preganglionic neurotransmitter for both the PNS and SNS is Ach. The postganglionic fibers of the SNS and PNS are anatomically and physiologically similar. The terminals branch out into terminal effector plexuses. One terminal branches to thousands of effector cells. The terminal ending is called a varicosity. Each varicosity contains vesicles within which the neurotransmitter is stored. (See page 331: Autonomic Nervous System: Neurotransmission; page 332: Parasympathetic Nervous System Neurotransmission; and page 332: Sympathetic Nervous System Neurotransmission.) 8. Which of the following statements regarding the parasympathetic nervous system (PNS) is TRUE? A. In addition to acetylcholinesterase, pseudocholinesterase also plays a significant role in the termination of acetylcholine (Ach). B. Acetylcholine is stored in presynaptic vesicles and is released in small amounts called quanta. C. After it is released, Ach is taken up by the presynaptic membrane for release again.
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D. Drugs that alter calcium release do not affect the release of Ach because its release is calcium independent. E. Ach is formed by acetylation of choline by the enzyme acetylcholinesterase. 8. B. Ach was once thought to be the only neurotransmitter; however, it is now believed that vasoactive intestinal peptide may play a role as a secondary neurotransmitter. Ach is formed within the presynaptic membrane by acetylation of choline with acetylcoenzyme. This process is catalyzed by choline acetyltransferase. The active product of this reaction, Ach, is stored in presynaptic vesicles. The depolarization of the end plate results in mass quantum release of Ach into the synaptic cleft. This release is dependent on calcium influx. Drugs that alter calcium influx may decrease the release of Ach. Ach is removed by rapid hydrolysis by the enzyme acetylcholinesterase. This enzyme is found in neurons, at the neuromuscular junction, and in various other tissues of the body. A similar enzyme, pseudocholinesterase or plasma cholinesterase, is also found throughout the body but only to a limited extent in nervous tissue. It does not appear to be physiologically important in the termination of the action of Ach. Both acetylcholinesterase and pseudocholinesterase hydrolyze Ach as well as other esters (e.g., the ester-type local anesthetics), but they may be distinguished by specific biochemical tests. (See page 332: Parasympathetic Nervous System Neurotransmission and page 332: Metabolism.) 9. All of the following statements regarding the sympathetic nervous system (SNS) are true EXCEPT: A. Epinephrine and norepinephrine are mediators of the peripheral SNS. B. In the adrenal medulla, the preganglionic neurotransmitter is acetylcholine (Ach). C. Chromaffin cells in the adrenal medulla are responsible for release of epinephrine and norepinephrine. D. The massive release of norepinephrine and epinephrine is the “fight or flight” response and lasts approximately 10 times as long as local direct stimulation.
E. Equal amounts of epinephrine and norepinephrine are released during stimulation of the adrenal medulla. 9. E. Epinephrine and norepinephrine are mediators of SNS peripheral activity. Adenosine triphosphate may be an additional neurotransmitter. In the adrenal medulla, Ach is the primary neurotransmitter at the preganglionic site. It causes release of norepinephrine and epinephrine from the chromaffin cells. These cells are considered the postganglionic neurons. Stimulation of the adrenal medulla results in massive release of epinephrine and norepinephrine, which lasts 10 times as long as local direct stimulation. Epinephrine release is greater in proportion to norepinephrine release. (See page 332: Sympathetic Nervous System Neurotransmission.) 10. Which of the following statements about catecholamines is TRUE? A. Circulating catecholamines are responsible for stimulating receptors in the central nervous system during the “fight or flight” response. B. The only brain catecholamine is dopamine. C. Endogenous catecholamines are dopamine, epinephrine, and norepinephrine. D. Catecholamines have only a direct effect on adrenergic receptors. E. Intermediate precursors of catecholamine synthesis have no effect on adrenergic receptors. 10. C. A catecholamine is a compound consisting of a catechol nucleus and amine site chain. Endogenous catecholamines are dopamine, norepinephrine, and epinephrine. Epinephrine is the precursor of norepinephrine synthesis and has an effect on adrenergic receptor sites. Dopamine is the primary neurotransmitter of the brain. Catecholamines may have a direct or indirect effect on receptors. The indirect effect is mediated through the release of stored neurotransmitter. Direct effects are independent of norepinephrine release. Some drugs may have a mixed mode of action. The brain contains both noradrenergic and dopaminergic receptors, but circulating catecholamines do not cross the blood–brain barrier. The catecholamines present in the brain are synthesized there. (See page 333: Catecholamines: The First Messenger.)
11. All of the following statements regarding the autonomic receptors are true EXCEPT: A. Acetylcholine (Ach) is the neurotransmitter in the parasympathetic nervous system (PNS), at preganglionic receptors of the sympathetic nervous system (SNS), and at the neuromuscular junction. B. Muscarinic receptors in the myocardium are stimulated by Ach and inhibit the release of norepinephrine. C. The two subdivisions of cholinergic receptors are muscarinic and nicotinic. D. Muscarinic stimulation causes tachycardia, inotropism, bronchodilation, and miosis. E. Nicotinic receptors are located in the SNS. 11. D. Cholinergic receptors are subdivided into muscarinic and nicotinic receptors. The nicotinic receptors are located at the preganglionic receptors of the SNS and PNS and at the neuromuscular junction of striated muscle. Muscarinic receptors are primarily associated with the postganglionic junctions of the PNS. PNS muscarinic stimulation causes bradycardia, decreased inotropism, bronchoconstriction, miosis, salivation, gastrointestinal hypermotility, and increased gastric acid secretion. Muscarinic receptors are also found on the presynaptic membrane of sympathetic nerve terminals in the myocardium, coronary vessels, and peripheral vasculature. These are referred to as adrenergic muscarinic receptors because of their location; however, they are stimulated by Ach. Stimulation of these receptors inhibits release of norepinephrine in a manner similar to α 2 receptor stimulation. (See page 334: Receptors.) 12. Which of the following statements regarding the α receptors is TRUE? A. The α 1 receptors result in no positive inotropic effect on the myocardium. B. Whereas the α 1 receptors appear to be confined to the postsynaptic membrane, the α 2 receptors are located on presynaptic and postsynaptic membranes.
C. The presynaptic α 2 receptors do not play a significant role in reducing sympathetic outflow. D. The α 1 agonists, such as phenylephrine, have an effect on coronary resistance by creating vasoconstriction and hence consistently contribute to coronary ischemia. E. Epinephrine is a more potent venoconstrictor than norepinephrine. 12. B. The α 1 receptors are believed to have a positive inotropic effect on cardiac tissues in most mammals. Enhanced α 1 activity may play a role in malignant arrhythmias. Drugs such as prazosin may have antiarrhythmic properties. The α 2 receptors are located at both the presynaptic and postsynaptic membranes. The α 1 receptors are located postsynaptically. The ratio of postsynaptic α 1 to α 2 receptors is approximately 1:1. The α 2 presynaptic receptors play a significant role in reducing sympathetic outflow. This results in decreases in systemic vascular resistance, cardiac output, and heart rate. In the CNS, these receptors may contribute to analgesia and sedation. The α 1 receptors in the epicardial vessels only contribute 5% of the total resistance in the normal coronary circulation. Therefore, phenylephrine probably has minimal effect on coronary resistance. Norepinephrine is the most potent venoconstrictor. (See page 335: α -Adrenergic Receptors.) 13. All of the following statements regarding β -adrenergic receptors are true EXCEPT: A. The β receptors are found in both presynaptic and postsynaptic membranes. B. Activation of the presynaptic β 2 receptor has the same physiologic response as antagonism of the presynaptic α 2 receptor. C. The postsynaptic β 2 receptors are noninnervated and respond to circulating catecholamines. D. The β 2 receptors are primarily located postsynaptically in the myocardium, sinoatrial node, and ventricular conduction system.
E. The β 1 receptors are innervated receptors responding to neuronally released norepinephrine. 13. D. β 1 and β 2 are the two subtypes of β -adrenergic receptors. The β 1 receptors are located in the myocardium, sinoatrial node, and ventricular conduction system. They are innervated and respond to neuronally released norepinephrine. The β 1 receptors are located only postsynaptically. The β 2 receptors have the same distribution but are presynaptic. The effects of activation of presynaptic β 2 receptors are diametrically opposed to α 2 presynaptic receptors. The β 2 presynaptic receptors accelerate endogenous norepinephrine release. Antagonism of these receptors results in a physiologic response that is similar to activation of presynaptic α 2 receptors. (See page 339: β -Adrenergic Receptors.) 14. Which of the following statements regarding the β receptors in the heart and peripheral vessels is FALSE? A. Both the β 1 and β 2 receptors are coupled to adenylate cyclase. P B. Increased catecholamine levels in heart failure leads to a larger downregulation of β 2 receptors compared with β 1 receptors. C. Whereas the inotropic effect of epinephrine is mediated via β and β 2 receptors, the inotropic effect of norepinephrine is mediated entirely through β 1 receptors.
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D. The postsynaptic β 1 receptors are predominantly found in the myocardium, sinoatrial node, and ventricular conduction system. The β 2 receptors have the same distribution but are presynaptic. E. The β 2 receptors approximate 20% to 30% of β receptors in the myocardium. 14. B. Both the β 1 and β 2 receptors are functionally coupled to adenylate cyclase, suggesting a similar involvement in the regulation of inotropism and chronotropism. The postsynaptic β 1 receptors are
distributed predominantly to the myocardium, the sinoatrial node, and the ventricular conduction system. The β 2 receptors have the same distribution but are presynaptic. Activation of the presynaptic β 2 receptor accelerates the release of norepinephrine into the synaptic cleft. The β 2 receptor approximates 20% to 30% of the β receptors in the ventricular myocardium and up to 40% of the β receptors in the atrium. Whereas the effect of norepinephrine on inotropism in the normal heart is mediated entirely through the postsynaptic β 1 receptor, the inotropic effects of ephedrine are mediated through both the β 1 and β 2 myocardial receptors. (See page 339: β Receptors in the Cardiovascular System.) 15. Which of the following statements regarding dopamine receptors is TRUE? A. The dopamine-1 receptors are located postsynaptically. B. The dopamine-2 receptors are located only presynaptically. C. The dopamine receptors have been located in the myocardium and are responsible for increased inotropism. D. The dopamine receptors inhibit the release of prolactin in the hypothalamus. E. The dopamine receptors located on vascular smooth muscle of the kidneys and mesentery produce regional vasoconstriction. 15. A. The dopamine receptors are of two types, dopamine-1 and dopamine-2. Whereas the type 1 receptors are located postsynaptically, the type 2 receptors are located both presynaptically and postsynaptically. Dopamine receptors have not been located in the myocardium. They are located in the hypothalamus, where they enhance the release of prolactin. They also are located in the basal ganglia, where they coordinate motor function. Dopamine receptors in the smooth muscle of the kidneys and mesentery produce vasodilation, resulting in increased blood flow to these organs. (See page 340: Dopaminergic Receptors.)
16. Which of the following statements regarding the baroreceptors is TRUE? A. Impulses from the carotid sinus and aortic arch reach the vasomotor center through the hypoglossal and the vagal nerve, respectively. B. Increased sensory input from the baroreceptors caused by decreased blood pressure inhibits sympathetic nervous system (SNS) effector traffic. C. The Valsalva maneuver can be used to identify patients at risk for autonomic nervous system (ANS) instability. D. Dysfunction in the SNS is suspected if prolonged hypertension develops during the forced expiration phase of the Valsalva maneuver. E. The presence of “overshoot” in blood pressure at the end of the Valsalva maneuver indicates dysfunction of the sympathetic nervous system (SNS). 16. C. Impulses from the carotid sinus and aortic arch reach the medullary vasomotor center by the glossopharyngeal and vagus nerves, respectively. Increased sensory traffic from the baroreceptors, caused by increased blood pressure, inhibits SNS effector traffic. The relative increase in vagal tone produces vasodilation, slowing of the heart rate, and a lowering of the blood pressure. Real increases in vagal tone occur when the blood pressure exceeds normal limits. The arterial baroreceptor reflex can best be demonstrated by the Valsalva maneuver. The arterial blood pressure increases momentarily as the intrathoracic blood is forced into the heart (preload). Sustained intrathoracic pressure diminishes venous return, reduces the cardiac output, and decreases the blood pressure. Reflex vasoconstriction and tachycardia ensue. The blood pressure returns to normal with release of the forced expiration but then briefly “overshoots” because of the vasoconstriction and increased venous return. A slowing of the heart rate accompanies the overshoot in pressure. The Valsalva maneuver has been used to identify patients at risk for ANS instability. Dysfunction of the SNS is implicated if exaggerated and prolonged hypotension develops during the forced expiration phase. In addition, the overshoot at the end of the Valsalva maneuver is absent. (See page 341: Baroreceptors.)
17. Which of the following is the principal site of autonomic nervous system (ANS) organization and long-term blood pressure control? A. Cerebral cortex B. Hypothalamus C. Medulla D. Pons E. Cerebellum 17. B. The cerebral cortex is the highest level of ANS integration. Fainting at the sight of blood is an example of this higher level of somatic and ANS integration. The principal site of ANS organization is the hypothalamus. Long-term blood pressure control, reactions to physical and emotional stress, sleep, and sexual reflexes are regulated through the hypothalamus. The medulla oblongata and pons are the vital centers of acute ANS organization. Together, they integrate momentary hemodynamic adjustments and maintain the sequence and automaticity of ventilation. (See page 327: Autonomic Nervous System.) 18. In which of the following organs do the preganglionic fibers pass directly without synapsing in a ganglion? A. Sweat glands B. Adrenal gland C. Spleen D. Liver E. Pancreas 18. B. The efferent sympathetic nervous system (SNS) is referred to as the thoracolumbar nervous system. The preganglionic fibers of the SNS (thoracolumbar division) originate in the intermediolateral gray column of the 12 thoracic (T1-T12) and the first three lumbar segments (L1-L3) of the spinal cord. The myelinated axons of these nerve cells leave the spinal cord with the motor fibers to form the white (myelinated) communicating rami. The rami enter one of the paired 22 sympathetic ganglia at their respective segmental levels. Upon entering the paravertebral ganglia of the lateral sympathetic chain, the preganglionic fiber may follow one of three courses: synapse with postganglionic fibers
in ganglia at the level of exit; course upward or downward in the trunk of the SNS chain to synapse in ganglia at other levels; or track for variable distances through the sympathetic chain and exit without synapsing to terminate in an outlying, unpaired SNS collateral ganglion. The adrenal gland is an exception to the rule. The preganglionic fibers pass directly into the adrenal medulla without synapsing in a ganglion. (See page 329: Sympathetic Nervous System.) 19. Which of the following statements about dobutamine (DBT) is FALSE? A. Dobutamine does not cause norepinephrine release or stimulate dopamine receptors. B. Dobutamine is a synthetic catecholamine modified from the classic inodilator isoproterenol. C. Dobutamine increases the heart rate more than epinephrine for a given increase in cardiac output. D. Dobutamine is a coronary artery constrictor. E. Dobutamine is highly controllable, with a half-life of 2 minutes. 19. D. Dobutamine is a synthetic catecholamine modified from the classic inodilator isoproterenol. It does not cause norepinephrine release or stimulate dopamine receptors. Dobutamine possesses weak α 1 agonism, which can be unmasked by β blockade as a prompt and dramatic increase in blood pressure. Dobutamine increases the heart rate more than epinephrine for a given increase in cardiac output. Dobutamine is a coronary vasodilator. Dobutamine is highly controllable, with a half-life of 2 minutes. (See page 352: Dobutamine.) 20. Which of the following statements is FALSE regarding fenoldopam? A. Fenoldopam is a selective dopamine-1 agonist with no α or β receptor activity. B. Fenoldopam has direct natriuretic and diuretic properties. C. Concomitant use with beta-blockers increases the effective dose of fenoldopam. D. Fenoldopam has an elimination half-life of 5 minutes.
E. Fenoldopam reduces mortality in patients with acute kidney injury. 20. C. Fenoldopam, a benzazepine derivative, is a selective dopamine-1 agonist with no α or β receptor activity. Intravenous fenoldopam has direct natriuretic and diuretic properties and promotes an increase in creatinine clearance. Fenoldopam has an elimination half-life of 5 minutes. In a recent and complete meta-analysis, Landoni et al suggest that fenoldopam reduces the risk of acute tubular necrosis, the need for renal replacement therapy, and overall mortality in patients with acute kidney injury. Concomitant use with beta-blockers reduces the effective dose of fenoldopam. (See page 354: Fenoldopam.) 21. Which of the following symptoms is not included under clonidine withdrawal syndrome? A. Hypertension B. Headache C. Tachycardia D. Somnolence E. Sweating 21. D. One of the more worrisome complications of chronic clonidine use is a withdrawal syndrome upon acute discontinuation of the drug. This usually occurs about 18 hours after discontinuation. The signs and symptoms are hypertension, tachycardia, insomnia, flushing, headache, apprehension, sweating, and tremulousness. It lasts for 24 to 72 hours and is most likely to occur in patients taking more than 1.2 mg/day of clonidine. The withdrawal syndrome has been noted postoperatively in patients withdrawn from clonidine before surgery. The withdrawal syndrome can be confused with anesthesia emergence symptoms, particularly in patients with uncontrolled hypertension. Absent the availability of the oral route in the surgical patient, withdrawal can be treated with transdermal clonidine or more rapidly with rectal clonidine. (See page 354: Clonidine.) For questions 22 to 30, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct.
22. Which of the following is/are the side effects of α- blockers? 1. Hypotension 2. Orthostatic hypotension 3. Nasal stuffiness 4. Mydriasis 22. A. Drugs that bind selectively to α -adrenergic receptors block the action of endogenous catecholamines or moderate the effects of exogenous adrenergics. The resultant effects may be ascribed to either the blockade effect to α -adrenergic agonists or to unopposed β adrenergic receptor activity. The effect is smooth muscle relaxation. The prominent clinical effects of α -blockers include hypotension, orthostatic hypotension, tachycardia, miosis, nasal stuffiness, diarrhea, and inhibition of ejaculation. (See page 358: α- Antagonists.) 23. Which of the following is/are cardioselective beta-blockers? 1. Atenolol 2. Esmolol 3. Metoprolol 4. Nadolol 23. A. Nonselective β -antagonists are referred to as first-generation β blockers. These drugs include propranolol, nadolol, sotalol, and timolol. Second-generation drugs are those considered selective for β 1adrenergic blockade and include atenolol, esmolol, and metoprolol. (See page 359: β- Antagonists.) P 24. Which of the following is/are interactions of the autonomic nervous system (ANS) with endocrine regulatory systems? 1. Release of antidiuretic hormone secondary to changes in plasma osmolality 2. α - or β -Receptor stimulation in the pancreas 3. Release of renin from the juxtaglomerular apparatus 4. Adrenal cortical function
24. E. The ANS is related to several endocrine systems that control blood pressure and homeostasis. Antidiuretic hormone (ADH) is secreted by the hypothalamus in response to changes in plasma osmolality. However, many factors, such as stress, pain, hypoxia, anesthesia, and surgery, may stimulate release of ADH. Whereas β stimulation of the pancreas increases insulin release, α stimulation decreases it. The complex rennin–angiotensin system modulates blood pressure and water and electrolyte homeostasis. Renin release from the juxtaglomerular complex acts on plasma angiotensinogen II, a potent vasoconstrictor. The ANS is also closely linked to adrenocortical function; glucocorticoids modulate epinephrine synthesis. (See page 342: Interaction with Other Regulatory Systems.) 25. Which of the following is/are mechanisms by which drugs may act on prejunctional membranes? 1. Interference with transmitter synthesis 2. Interference with transmitter storage 3. Interference with transmitter release 4. Interference with the shape or composition of the receptor 25. A. Drugs interact at the prejunctional membrane by a number of different mechanisms, including interfering with transmitter synthesis, storage, release, or reuptake or modifying neurotransmitter metabolism. Drugs acting at postjunctional sites may directly stimulate postjunctional receptors and interfere with the transmitter agonist at postjunctional receptors. (See page 343: Mode of Action.) 26. Features of ganglionic drugs include: 1. nonselective drugs that affect both the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) 2. unpredictable side effects that limit their usefulness 3. nicotine as the prototypical agonist 4. histamine release at low doses 26. A. Autonomic ganglia are similar in that acetylcholine is the primary neurotransmitter in both the PNS and the SNS. Most ganglionic drugs are nonselective. This property makes them undesirable and unpredictable
and thus limits their clinical usefulness. Nicotine is the prototypical agonist. It stimulates autonomic ganglia and the neuromuscular junction at low concentrations. In high doses, it creates blockade. (See page 343: Ganglionic Drugs.) 27. Which of the following is/are properties of trimethaphan? 1. It is a drug equivalent to nitroprusside. 2. It has a short duration of action because of hydrolysis by pseudocholinesterase. 3. It causes pupillary constriction. 4. It affects the ability of acetylcholine (Ach) to bind to receptor sites. 27. C. Trimethaphan is the only ganglionic blocker currently available in the United States. It affects the ability of Ach to bind to receptor sites. Its side effects and short duration of action limit its usefulness, and tachyphylaxis develops quickly. Pupillary dilation limits its use in neurosurgical patients. It is not equivalent to nitroprusside. (See page 344: Antagonists.) 28. Which of the following statements regarding cholinomimetic drugs is/are TRUE? 1. There are three groups of these agents: esters, alkaloids, and anticholinesterases. 2. The choline esters (acetylcholine [Ach], methacholine, carbamylcholine, bethanechol) make up the group of indirect agents. 3. Ach has no therapeutic application because of its diffuse action and rapid hydrolysis. 4. Choline esters other than Ach are metabolized at a faster rate. 28. B. Cholinomimetic drugs act where acetylcholine (Ach) is a neurotransmitter. There are three groups of cholinergic drugs. The first two groups, which are direct muscarinic agents, are the choline esters (Ach, methacholine, carbamylcholine, bethanechol) and the alkaloids (pilocarpine, muscarine, arecoline). The third group consists of the indirect-acting agents: the anticholinesterases (physostigmine,
neostigmine, pyridostigmine, edrophonium, echothiophate). Ach has a diffuse action and is rapidly hydrolyzed, so it has no therapeutic applications. Other choline esters are more resistant to inactivation and therefore are more clinically useful. (See page 344: Muscarinic Agonists.) 29. Which of the following statements regarding anticholinesterases is/are TRUE? 1. All anticholinesterases are tertiary amines and therefore readily cross the blood–brain barrier. 2. The two types of anticholinesterase drugs are reversible and nonreversible. 3. Physostigmine is a quaternary ammonium compound that has no central muscarinic stimulation. 4. The two types of anticholinesterase agents are categorized by their site of cholinesterase inhibition. 29. C. Anticholinesterase drugs are classified as reversible and nonreversible. They are divided into two different types based on the site of inhibition on the cholinesterase enzyme. Agents that inhibit at the esteratic site are called acid-transferring inhibitors. These drugs are long acting (physostigmine, neostigmine, pyridostigmine). Drugs acting at the anionic site are called prosthetic, competitive inhibitors. These drugs tend to be short acting (e.g., edrophonium). Physostigmine is a tertiary amine and therefore crosses the blood–brain barrier. It is useful for reversing atropine poisoning but is not useful for reversing neuromuscular blockade. (See page 345: Indirect Cholinomimetics.) 30. Which of the following statements regarding anticholinesterase is/are true? 1. Most of the indirect-acting drugs inhibit both cholinesterase and pseudocholinesterase. 2. Muscarinic activity is evoked at higher concentrations than are necessary to produce the desired nicotinic effect. 3. Excess accumulation of acetylcholine (Ach) at the motor end plate produces a depolarizing block similar to succinylcholine or high doses of nicotine.
4. Edrophonium is an esteratic drug (works on the esteratic site of cholinesterase). 30. B. The indirect-acting cholinomimetic drugs are of greater importance to anesthesiologists than are the direct-acting cholinergic drugs. These drugs produce cholinomimetic effects indirectly as a result of inhibition or inactivation of the enzyme acetylcholinesterase, which normally destroys Ach by hydrolysis. They are referred to as cholinesterase inhibitors or anticholinesterases. Most of these drugs inhibit both acetylcholinesterase and pseudocholinesterase. The most prominent pharmacologic side effects of the anticholinesterase drugs are muscarinic. Their most useful actions are their nicotinic effects. Muscarinic activity is evoked by lower concentrations of Ach than are necessary to produce the desired nicotinic effect. For example, the anticholinesterase neostigmine reverses neuromuscular blockade by increasing Ach concentration at the muscle end plate, a nicotinic receptor. However, reversal of neuromuscular blockade can usually be produced safely only when the patient has been protected by atropine or another muscarinic antagonist. This prevents the untoward muscarinic effects of bradycardia, hypotension, bronchospasm, and intestinal spasm. Conversely, neuromuscular paralysis may be produced or increased if excessive anticholinesterase is used. Excess accumulation of Ach at the motor end plates produces a depolarizing block similar to that produced by succinylcholine or nicotine. The differences in duration of various anticholinesterases apparently depend on whether they inhibit the anionic or esteratic site of acetylcholinesterase. Therefore, the anticholinesterase drugs have also been pharmacologically subdivided. Drugs that inhibit the anionic site are called competitive inhibitors. Their action is the result of competition between the anticholinesterase and Ach for the anionic site. These drugs tend to be short acting. Edrophonium is an example of this type. (See page 345: Indirect Cholinomimetics.)
Chapter 16 Hemostasis and Transfusion Medicine 1. Which has the highest risk of ischemia under the conditions of isovolemic hemodilution? A. Bowel B. Heart C. Lung D. Liver E. Kidney 1. B. With isovolemic hemodilution, blood flow to the tissues increases, but this increased blood flow is not distributed equally to all tissue beds. Organs with higher extraction ratios (brain and heart) receive disproportionately more of the increase in blood flow than organs with low extraction ratios (muscle, skin, viscera). The redistribution of blood flow to the coronary circulation is the principal means by which the healthy heart compensates for anemia. Under basal conditions, the heart already has a high extraction ratio (50%–70% vs 30% in most tissues) and the primary compensation for anemia involves cardiac work (increasing cardiac output), so the heart must rely on redistributing blood flow to increase oxygen supply. These factors make the heart the organ at greatest risk under conditions of isovolemic hemodilution. When the heart can no longer increase either cardiac output or coronary blood flow, the limits of isovolemic hemodilution are reached. Further decreases in oxygen delivery will result in myocardial injury. (See page 379: Compensatory Mechanisms During Anemia.) 2. Which of the following is the most common infection associated with red blood cell (RBC) transfusion? A. Hepatitis A B. Human T-cell lymphotropic virus (HTLV-1 and HTLV-2) C. Hepatitis C
D. Human immunodeficiency virus (HIV) E. Hepatitis B 2. E. The rate of viral infectivity has decreased dramatically in the past 2 decades. In particular, the advent of universal (in the United States) nucleic acid testing (NAT) for HIV and the hepatitis C virus (HCV) has reduced the frequency of transmission of those agents to very low levels (one in 2 million). Hepatitis B remains the greatest risk (currently about one in 350,000 donor exposures). Transmission of hepatitis A virus (HAV) by transfusion has been very rare. Blood banks screen for HAV by history only, and there is no carrier state for this virus. HTLV-1 and HTLV-2 belong to the same retrovirus family as HIV. The incidence of clinical disease resulting from transmitted virus appears to be very low, and the transmission rate is very low, around one in 2.9 million. (See page 370: Infectious Risks Associated with Blood Product Administration.) 3. Noninfectious risks associated with transfusion include all EXCEPT: A. hypothermia B. dilutional coagulopathy C. increase in 2,3 diphosphoglycerate D. hyperkalemia E. microaggregate delivery 3. C. Noninfectious risks associated with transfusion include hypothermia, dilutional coagulopathy, hyperkalemia, and microaggregate delivery. A meta-analysis concluded that even mild hypothermia increases blood loss. Hypothermia, after attempting to correct for covariates, is an independent predictor of mortality in trauma patients. Hypothermia has been associated with increased postoperative morbidity and mortality, including increased rates of postoperative infection. Administration of large volumes of fluid deficient in platelets and clotting factors results in coagulopathy as a consequence of dilution. Hazard exists if large volumes of stored blood are administered rapidly. Although there is only 20 to 60 mL of plasma in a unit of packed red blood cells, contemporary infusion devices allow blood to be transfused at rates of 500 to 1000 mL/ min. At these infusion rates, critical hyperkalemia can occur, and intraoperative
arrests have been documented. Microaggregates have been suspected in the pathogenesis of pulmonary insufficiency after large volume transfusion. (See page 376: Other Noninfectious Risks Associated with Transfusions.) 4. Which of the following is true regarding coagulation? A. Most clotting factors circulate in an active form. B. Most clotting factors are synthesized extrahepatically. C. von Willebrand factor and coagulation factor VIII combine to form factor IX. D. Factors V and VIII have short storage half-lives. E. Seven clotting factors are vitamin K dependent. 4. D. Most of the clotting factors circulate as inactive proenzymes. Most clotting factors are synthesized by the liver. Factor VIII is actually a large two-molecule complex consisting of von Willebrand factor and coagulant factor VIII. Four clotting factors (II, VII, IX, X) are vitamin K dependent. Factors V and VIII have short storage half-lives. Factors V and VIII are also referred to as the “labile factors” because their coagulant activity is not durable in stored blood. Although packed red blood cells contain residual plasma with clotting factors, massive transfusion with stored blood nonetheless lead to a dilutional coagulopathy because of diminished activity of factors V and VII. (See page 386: The Coagulation Mechanism.) 5. Which of the following is not contained in cryoprecipitate? A. Factor VIII B. Factor X C. von Willebrand factor (vWF) D. Fibrinogen E. Fibronectin 5. B. Factor X is not contained in cryoprecipitate. Cryoprecipitate contains factor VIII, vWF, fibrinogen, fibronectin, and factor XIII. (See page 378: Blood Products and Transfusion Thresholds: Cryoprecipitate.)
6. Which of the following is not a vitamin K–dependent factor? A. II B. V C. VII D. IX E. X 6. B. Most of the coagulation proteins are synthesized by the liver. Four of the clotting factors (II, VII, IX, and X) require vitamin K for proper synthesis. (See page 386: The Coagulation Mechanism.) 7. Which of the following is not a common cause of platelet dysfunction? A. Dialysis B. Use of nonsteroidal anti-inflammatory drugs (NSAIDs) C. Chronic liver disease D. Disseminated intravascular coagulopathy (DIC) E. Cardiopulmonary bypass (CPB) 7. A. The causes of thrombocytopenia may be categorized as follows: (1) inadequate production by the bone marrow, (2) increased peripheral consumption or destruction (non–immune mediated), (3) increased peripheral destruction (immune mediated), (4) dilution of circulating platelets, and (5) sequestration. Bone marrow production of platelets may be impaired in many ways. Chronic disease states such as uremia and liver disease may cause bone marrow suppression. The many conditions that cause DIC also cause platelets to be consumed or destroyed faster than they can be produced. Numerous medications are administered expressly for the purpose of platelet inhibition to reduce the risk of myocardial infarction, stroke, and other thromboembolic complications. These medications induce platelet dysfunction by several mechanisms, including inhibition of cyclo-oxygenase, inhibition of phosphodiesterase, adenosine diphosphate receptor antagonism, and blockade of the glycoprotein IIb/IIIa receptor. Indomethacin, phenylbutazone, and all the NSAIDs similarly inhibit cyclo-oxygenase. Platelets are subject to contact activation by the CPB circuit, thus
causing their numbers to decline. Platelet dysfunction is common in patients with uremia. The accumulation of guanidinosuccinic acid and hydroxyphenolic acid is thought to contribute to this dysfunction through interference with the platelet's ability to expose the PF3 phospholipid surface. These compounds are dialyzable, so dialysis frequently improves the hemostatic defect associated with uremia. (See page 398: Thrombocytopenia.) For questions 8 to 27, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 8. Regarding autologous blood conservation strategies, which of the following statements is FALSE? 1. Regarding preoperative autologous donation, 4 U is typically the maximum possible donation. 2. Erythropoietin is often accepted by Jehovah's Witnesses. 3. Body weight of less than 100 lb is a relative contraindication to preoperative autologous donation. 4. Acute normovolemic hemodilution may reduce the amount transfused by 3 to 4 U per patient. 8. D. A recent meta-analysis reported that acute normovolemic hemodilution does not achieve complete avoidance of allogeneic blood but that when transfusion is necessary, the amount transfused is reduced by 1 to 2 U per patient. Erythropoietin, a recombinant product, is often accepted by Jehovah's Witnesses, and its efficacy in that population has been demonstrated. Severe aortic stenosis, significant coronary disease or myocardial dysfunction, and low initial hematocrit and blood volume (body weight 70%) are now obtained by
apheresis. One apheresis unit increases the platelet count by 30,000 to 60,000/uL. A common practice is to administer either 1 U of apheresis platelets to an adult or 1 U of platelet concentrate per 10 kg of body weight. The increase in platelets must be verified by platelet count, especially in patients who may have been alloimmunized by frequent platelet administration. A single apheresis unit (referred to as “apheresis platelets”) is obtained from a single donor at a single session. (See page 378: Blood Products and Transfusion Thresholds: Platelets.) 20. Which of the following statements regarding antithrombin III (ATIII) is/are TRUE? 1. It is inactivated by heparin. 2. It is a naturally occurring anticoagulant. 3. It is nonfunctional without the heparin cofactor. 4. In the presence of heparin, it can bind activated factors IX, X, and XII to accelerate anticoagulation. 20. C. ATIII is a circulating serine protease inhibitor that binds to thrombin and thereby inactivates it. It can bind and inactivate each of the activated clotting factors of the classical “intrinsic” coagulation cascade—factors XIIa, XIa, IXa, and Xa. In the absence of heparin, ATIII has a relatively low affinity for thrombin. However, when heparin is bound to ATIII, the efficiency of binding of ATIII to thrombin and the other factors increases dramatically. (See page 391: Thrombin and Antithrombin III.) P 21. Which of the following statements regarding fibrinolysis is/are TRUE? 1. Tissue plasminogen activator (t-PA) is produced by vascular endothelial cells. 2. The primary fibrinolytic enzyme is t-PA. 3. t-PA differs from streptokinase in that its action is more localized. 4. Fibrin degradation products are produced by the action of t-PA on plasminogen.
21. B. The process of fibrinolysis leads to dissolution of fibrin clots. Fibrinolysis serves to remodel fibrin clots and “recanalize” vessels that have been occluded by thrombosis. The primary fibrinolytic enzyme is plasmin, which is derived by the conversion of plasminogen to plasmin in the presence of t-PA and fibrin. Fibrin split products or fibrin degradation products are produced by the action of plasmin on fibrin clots. The therapeutic fibrinolytic agents streptokinase and urokinase differ from t-PA in that they activate circulating plasminogen, leading to more widespread fibrinolysis. (See page 389: Fibrinolysis.) 22. Which of the following statements regarding the laboratory evaluation of coagulation is/are TRUE? 1. The prothrombin time (PT) tests the extrinsic pathway of coagulation by adding tissue factors to whole blood. 2. The thrombin time is prolonged by low amounts of any of the factors that prolong the PT. 3. The international normalized ratio (INR) standardizes the PT results obtained from varying thromboplastin reagents. 4. The reptilase test uses snake venoms to confirm abnormal INR numbers. 22. B. The PT is measured by adding tissue thromboplastin or tissue factor to the blood and measuring the time until clot formation occurs. PT is prolonged if deficiencies; abnormalities; or inhibitors of factors I, II, V, VII, or X exist. This tests the classical extrinsic pathway. Because different thromboplastin reagents produce values with different normal ranges, comparison of PT results among laboratories is difficult. The INR value takes into account the different sensitivities of varying reagents and allows INR results to be directly compared from one laboratory to another. The thrombin time measures the ability of thrombin to convert fibrinogen to fibrin. This test bypasses all other preceding reactions and is not necessarily prolonged by abnormalities of many of the factors of the extrinsic pathway. Reptilase, a snake venom, converts fibrinogen to fibrin; this is unaffected by the presence of heparin. The reptilase test is used to differentiate a prolonged thrombin time as a result of heparin versus fibrin degradation products. (See page 392: Laboratory Evaluation of Coagulation.)
23. Which of the following statements regarding von Willebrand disease is/are TRUE? 1. It is a rare hereditary bleeding disorder. 2. The activated partial thromboplastin time (aPTT) is commonly prolonged because of the diminished half-life of factor VIII in von Willebrand disease. 3. Desmopressin (DDAVP) helps patients with all types of von Willebrand disease to some extent. 4. Patients have a prolonged bleeding time (BT) and normal platelet count. 23. D. von Willebrand disease is the most common hereditary bleeding disorder in humans. When von Willebrand factor is deficient, platelet function is impaired, leading to an abnormal BT in the presence of normal platelet count. The aPTT and PT may be normal in patients with von Willebrand disease. Although the half-life of factor VIII:C is diminished in people with von Willebrand disease, they usually have sufficient VIII:C to yield a normal aPTT in basal conditions. DDAVP is effective first-line therapy for most (∼80%) patients with von Willebrand disease, including those with types 1 and 2A disease. However, the recognition of subtype 2B is important because DDAVP causes thrombocytopenia in these patients. (See page 396: von Willebrand Disease.) 24. Which of the following statements regarding hemophilia is/are TRUE? 1. Hemophilia A is caused by a deficiency of factor VIII activity. 2. Hemophilia B is an autosomal recessive disorder that occurs almost exclusively in Ashkenazi Jews. 3. Hemophilia A may be treated with desmopressin (DDAVP). 4. Patients with hemophilia A usually have an abnormal prothrombin time (PT) and bleeding time (BT). 24. B. Whereas hemophilia A is caused by a deficiency of factor VIII activity, hemophilia B (Christmas disease) is caused by a deficiency of factor IX. Both hemophilia A and B are sex-linked recessive disorders,
which therefore occur almost exclusively in boys and men. Hemophilia C is an autosomal recessive disorder that occurs almost exclusively in Ashkenazi Jews. Patients with hemophilia A are generally treated with factor VIII concentrates. However, DDAVP is helpful in increasing plasma factor VIII and von Willebrand factor concentrations; it is most effective in patients with factor VIII:C levels above 5%. Laboratory diagnosis of hemophilia A is based on the finding of a prolonged aPTT and a specific factor assay demonstrating deficiency of factor VIII. The patient will have a normal PT and a normal BT. (See page 397: The Hemophilias.) 25. Which of the following statements regarding disseminated intravascular coagulation (DIC) is/are TRUE? 1. It is triggered by the appearance of excessive procoagulant material (tissue factor or equivalent) in the circulation. 2. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) may remain normal. 3. Activated protein C should be considered in any sustained episode of DIC. 4. Heparin has been advocated in situations in which thrombosis is clinically problematic. 25. E. DIC is triggered by the appearance of procoagulant material (tissue factor or equivalent) in the circulation in amounts sufficient to overwhelm the mechanisms that normally restrain and localize clot formation. PT and aPTT may remain normal despite decreasing factor levels because of the presence of high levels of activated factors, including thrombin and Xa. Use of heparin has been advocated, but the contemporary practice is to restrict its use to only situations in which thrombosis is clinically problematic. An insufficiency in the protein C endogenous coagulation inhibition system is thought to contribute to the prothrombotic state in individuals with DIC. Activated protein C has been shown to decrease mortality and organ failure in patients with sepsis, and this improvement is also evident among patients with sepsis with overt DIC. The use of this agent should be considered in all sustained episodes of DIC. (See page 402: Disseminated Intravascular Coagulation.)
26. Which of the following statements regarding low-molecularweight heparins (LMWHs) is/are TRUE? 1. They are associated with a lesser incidence of heparin-induced thrombocytopenia. 2. Protamine successfully neutralizes LMWH. 3. Their half-life is longer than that of standard heparin. 4. They cause more platelet inhibition than standard heparin. 26. B. Protamine neutralization of LMWH is reported to be incomplete. The half-life is longer than that of standard heparin, allowing for onceper-day dosing. It appears to cause less platelet inhibition and is associated with a lower incidence of heparin-induced thrombocytopenia than standard heparin. (See page 399: Acquired Disorders of Clotting Factors.) 27. Which of the following statements regarding thromboelastography is/are FALSE? 1. It measures platelet aggregation, coagulation, and fibrinolysis. 2. The maximum amplitude (MA) is a measure of the strength of the fully formed clot. 3. A (MA + 60)/MA ratio of less than 0.85 is evidence of abnormal fibrinolysis. 4. The teardrop configuration usually prompts the administration of red blood cells. 27. D. Thromboelastography provides a measure of the mechanical properties of evolving clot as a function of time. A principal advantage is that the processes it measures require the integrated action of all the elements of the hemostatic process: platelet aggregation, coagulation, and fibrinolysis. The (MA + 60)/MA ratio has been used most widely. A ratio of less than 0.85 is evidence of abnormal fibrinolysis. In clinical practice, particularly in liver transplantation, a nonquantitative appreciation of the typical teardrop shape is used more often to support a diagnosis of increased fibrinolysis than are specific numerical values. (See page 394: The Thromboelastogram.)
Chapter 17 Inhaled Anesthetics 1. Which of the following statements regarding minimum alveolar concentration (MAC) is FALSE? A. Pregnancy decreases MAC. B. The MAC of inhaled drugs is additive. C. MAC is lowered in preterm neonates compared with term neonates. D. Acute ethanol administration increases MAC. E. MAC in an 80-year-old patient is only three fourths that of a young adult. 1. D. MAC is influenced by age; in humans, MAC is lower in preterm neonates than term neonates. It is higher in term infants than at any other age. Anesthetic requirements decrease with age: An 80-year-old patient requires only three fourths the alveolar concentration of anesthetic that is required for a young adult. Pregnancy decreases MAC in sheep. Acute ethanol administration decreases MAC. (See page 424: Minimum Alveolar Concentration [MAC]; page 424: Table 17-4; and page 425: Table 17-5.) 2. Which of the following statements about minimum alveolar concentration (MAC) is FALSE? A. MAC-awake is the alveolar concentration at which 50% of patients respond to the command “open your eyes.” B. Standard MAC values are roughly additive. C. MAC-block adrenergic response (BAR) is the alveolar concentration that blocks the adrenergic response to noxious stimuli in 50% of patients. D. MAC-awake for halothane is approximately equivalent to standard MAC.
E. MAC-BAR is 1.5 times the standard MAC value. 2. D. MAC-awake is the dose at which 50% of patients respond to the command “open your eyes.” The alveolar concentration at this point is approximately 50% of the standard MAC value for halothane. MAC-BAR is the alveolar concentration required to block the adrenergic response to noxious stimuli in 50% of patients; this value is approximately 1.5 times the standard MAC value. MAC values are roughly additive. (See page 424: Minimum Alveolar Concentration [MAC].) 3. Which of the following best relates the relative degree to which inhalational anesthetics decrease cerebral metabolic rate? A. Sevoflurane = Halothane < Isoflurane B. Isoflurane < Halothane < Sevoflurane C. Sevoflurane < Isoflurane < Halothane D. Isoflurane = Sevoflurane > Halothane E. Halothane < Isoflurane = Sevoflurane 3. D. Each of the potent inhaled anesthetics decreases cerebral metabolic oxygen consumption (CMRO2), with the order of effect from greatest to least being Isoflurane = Sevoflurane = Desflurane > Halothane. (See page 425: Cerebral Metabolic Rate and Electroencephalogram.) 4. Which of the following statements regarding the central nervous system (CNS) effects of inhalational agents is FALSE? A. All potent inhalational agents depress the cerebral metabolic rate (CMR). B. Desflurane and sevoflurane cause a similar decrease in CMR. C. After an isoelectric electroencephalogram (EEG) is achieved, a further increase in isoflurane concentration will further decrease the cerebral metabolic oxygen consumption (CMRO2). D. Isoflurane abolishes EEG activity at clinically used doses that are usually hemodynamically tolerable. E. Desflurane's effects on the CNS system are similar to isoflurane's.
4. C. It has been shown that after an isoelectric EEG is achieved with isoflurane, further increases in isoflurane's concentration do not lead to further decreases in CMR. Isoflurane abolishes EEG activity at clinically used doses that are usually hemodynamically tolerated. Desflurane and sevoflurane cause similar decreases in CMR. Desflurane's effects are similar to those of isoflurane. (See page 425: Cerebral Metabolic Rate and Electroencephalogram.) 5. True statements regarding inhalational agents include all of the following EXCEPT: A. A second gas effect exists for nearly every combination of inhaled drugs. B. The two major components of the second gas effect are the concentration effect and decreased solubility. C. For the more soluble anesthetics, augmentation of anesthetic delivery by increasing minute ventilation also increases the rate of increase in the ratio of the alveolar anesthetic concentration (FA) to the inspired anesthetic concentration (FI) over time (FA/FI). D. During emergence, washout of high concentrations of nitrous oxide can lower alveolar concentrations of O2 and CO2. E. The rate of alveolar concentration approaching the inspired concentration is inversely related to the blood solubility of the agent. 5. B. The rate at which the alveolar concentration approaches the inspired concentration is inversely related to the blood solubility of the anesthetic. Administration of high concentrations of one gas (e.g., nitrous oxide) facilitates the increase in alveolar concentration of another gas (e.g., halothane); this phenomenon is called the second gas effect. The two components of the second gas effect (increased ventilation [increased tracheal inflow] and the concentrating effect) are operative at the alveolar level. Although a second gas effect exists for nearly all combinations of inhaled drugs given simultaneously, it is most pronounced when nitrous oxide is used with a more soluble drug, such as halothane (the second gas). For more soluble anesthetics, increasing the
minute ventilation increases rate of increase in FA/FI. Emergence from anesthesia is more rapid with low blood or tissue anesthetic solubility, increased ventilation, and replacement of nitrous oxide with nitrogen. During washout of high concentrations of nitrous oxide, alveolar concentrations of O2 and CO2 can be lowered. This phenomenon is called diffusion hypoxia. (See page 419: Second Gas Effect and page 421: Exhalation and Recovery.) 6. True statements regarding the effects of anesthetics on the chemical control of breathing include all of the following EXCEPT: A. Subanesthetic concentrations of potent inhalational agents depress the hypoxic response in humans. B. The ventilatory response to CO2 is depressed by all inhalational agents. C. With a 2 minimum alveolar concentration (MAC) inhalational agent in a spontaneously breathing P patient, the apneic threshold is generally 5 mm Hg below the resting PaCO2. D. Residual effects of inhalation agents may impair the ventilatory drive of patients in the recovery room. E. Nitrous oxide decreases PaCO2 during spontaneous breathing. 6. E. The ventilatory response to CO2 is depressed more or less proportionately by all anesthetic agents. Apnea results if the anesthetic dose is high enough. If apnea occurs, the apneic threshold is approximately 4 to 5 mm Hg below the PaCO2 maintained during spontaneous breathing, regardless of the type of anesthesia. It should be anticipated that the PaCO2 will be 50 to 55 mm Hg at surgical planes of anesthesia when potent inhaled anesthetics are used. Surgical stimuli decrease this level by 4 to 5 mm Hg at an equivalent level of anesthesia. Nitrous oxide maintains (or may slightly increase) the PaCO2 during spontaneous breathing. Subanesthetic concentrations of halothane, enflurane, and isoflurane depress the hypoxic response in humans. Residual effects of inhalational agents may impair the ventilatory drive
of patients in the recovery room. (See page 433: Response to Carbon Dioxide and Hypoxemia.) 7. True statements concerning the hemodynamic effects of inhalational agents include all of the following EXCEPT: A. All potent inhaled agents decrease arterial pressure. B. Heart rate changes least with halothane and sevoflurane. C. Volatile anesthetics cause dose-dependent myocardial depression. D. Isoflurane causes greater slowing in the His-Purkinje system than does halothane. E. All inhalational agents attenuate baroreflex control of heart rate. 7. D. Volatile anesthetics cause dose-dependent myocardial depression. All the potent inhaled agents decrease arterial pressure in a doserelated manner. The mechanism of the decrease in blood pressure includes vasodilation, decreased cardiac output resulting from myocardial depression, and decreased sympathetic nervous system tone. The heart rate changes least with halothane and increases most with desflurane. Halothane causes a greater slowing of the His-Purkinje system than does isoflurane. (See page 427: The Circulatory System and page 428: Fig. 17-14.) 8. Which of the following statements regarding metabolism of inhaled agents is FALSE? A. The production of compound A is enhanced during low-flow anesthesia. B. Baralyme produces more compound A than soda lime. C. Compound A production is decreased by warm or very dry CO2 absorbents. D. The potential effect of compound A is renal toxicity. E. CO2 absorbents degrade all modern-day potent inhalational anesthetics.
8. C. Sevoflurane is degraded by CO2 absorbents to produce compound A. Baralyme produces more compound A than does soda lime, which can be attributed to slightly higher absorbent temperatures during CO2 extraction. The risk from compound A is renal tubular necrosis. Sevoflurane metabolism to compound A is enhanced in low-flow or closed-circuit breathing systems and by warm or very dry CO2 absorbents. All the potent inhaled agents (halothane, sevoflurane, enflurane, desflurane, and isoflurane) are degraded by CO2 absorbents. (See page 437: Anesthetic Degradation by Carbon Dioxide Absorbers.) 9. Which statement is FALSE regarding fluoride-induced nephrotoxicity? A. The treatment of choice is vasopressin. B. Sevoflurane transiently increases serum fluoride concentration. C. Fluoride-induced nephrotoxicity presents as high-output renal insufficiency. D. Obesity causes increased defluorination of isoflurane. E. Faster washout may contribute to the improved safety of sevoflurane regarding fluoride concentrations compared with enflurane. 9. A. Fluoride-induced nephrotoxicity, which is caused by inorganic fluoride, presents as high-output renal insufficiency that is unresponsive to vasopressin and is characterized by dilute polyuria, dehydration, serum hypernatremia, and hyperosmolality with elevated levels of blood urea nitrogen and creatinine. Sevoflurane undergoes 5% metabolism that transiently increases serum fluoride concentrations. The safety of sevoflurane regarding fluoride concentrations may be caused by a rapid decline in plasma fluoride concentrations because of less availability of the anesthetic for metabolism from a faster washout compared with enflurane. Factors such as total dose of anesthetic, liver enzyme induction, and obesity have been proven to enhance biotransformation (defluorination). (See page 438: Fluoride-Induced Nephrotoxicity.) 10. True statements regarding inhalational agents include all of the following EXCEPT:
A. Inhalational agents have muscle relaxant properties of their own. B. Situations that decrease hepatic blood flow make patients vulnerable to the effects of inhalational anesthetics on hepatic blood flow. C. Of the volatile anesthetics, halothane is the most potent trigger of caffeine-induced contractions. D. Volatile anesthetics cause a dose-dependent decrease in uterine smooth muscle contractility. E. No inhalational anesthetic has been shown to be teratogenic in animals. 10. E. The potent inhaled anesthetic agents not only potentiate the action of neuromuscular blocking drugs but also have muscle relaxant properties of their own. Situations that decrease hepatic blood flow or increase hepatic oxygen consumption make patients more vulnerable to the unwanted effects of volatile anesthetics on hepatic blood flow. Volatile anesthetic agents have been shown to be teratogenic in animal studies, but none has been shown to be teratogenic in humans. Halothane causes a stronger contraction to the caffeine-induced contracture test than isoflurane or enflurane. Volatile anesthetics produce a dose-dependent decrease in uterine smooth muscle contractility. (See page 435: Hepatic Effects.) 11. The FALSE statement concerning the effect of inhalational agents on cerebrospinal fluid (CSF) and cerebral blood flow (CBF) is: A. Sevoflurane at 1 minimum alveolar concentration (MAC) decreases CSF production. B. Desflurane at 1 MAC leaves CSF production unchanged or slightly increased. C. Isoflurane, sevoflurane, and desflurane cause far less cerebral vasodilation per MAC-multiple than halothane. D. Isoflurane significantly increases CSF production and decreases resistance to reabsorption. E. At high anesthetic doses, CBF is essentially pressure passive.
11. D. Isoflurane does not appear to alter CSF production but may increase, decrease, or leave unchanged the resistance to reabsorption, depending on the dose. Sevoflurane at 1 MAC depresses CSF production up to 40%. At 1 MAC, desflurane leaves CSF production unchanged or increased. All the potent agents increase CBF in a dose-dependent manner. Isoflurane, sevoflurane, and desflurane cause far less cerebral vasodilation per MAC-multiple than halothane. Because the volatile anesthetics are direct vasodilators, all of them are considered to diminish autoregulation in a dose-dependent fashion such that at high anesthetic doses, CBF is essentially pressure passive. In general, anesthetic effects on intracranial pressure via changes in CSF dynamics are clinically far less important than their effects on CBF. (See page 427: Cerebrospinal Fluid Production and Reabsorption and page 426: Cerebral Blood Flow, Flow-Metabolism Coupling, and Autoregulation.) For questions 12 and 13, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 12. TRUE statements regarding the effects of inhaled anesthetics on circulation include: 1. Spontaneous ventilation decreases systemic vascular resistance. 2. Sevoflurane provides a stable heart rate. 3. Desflurane slows sinoatrial (SA) node discharge. 4. Isoflurane is associated with an increase in heart rate. 12. E. Spontaneous ventilation is associated with higher PaCO2, causing a decrease in cerebral and systemic vascular resistance. Sevoflurane provides a stable heart rate. Desflurane, sevoflurane, and isoflurane are known to maintain cardiac output. Enflurane and isoflurane are associated with an increase in heart rate of 10% to 20% at 1 MAC. The SA node discharge rate is slowed by the volatile anesthetics. (See page 427: The Circulatory System.) 13. TRUE statements regarding inhaled anesthetics include: 1. The partial pressure is the pressure a gas exerts proportional to its fractional mass.
2. A low-solubility agent results in a fast increase in the ratio of the alveolar anesthetic concentration (FA) to the inspired anesthetic concentration (FI) over time (FA/FI). 3. The depth of anesthesia can be adjusted quickly. 4. Fat has a slow time for equilibration with blood. 13. E. The partial pressure is the pressure a gas exerts proportional to its fractional mass. The inhaled anesthetics with the lowest solubilities in the blood show the fastest increase in FA/FI. Fat has a slow time for equilibration with blood. (See page 414: Pharmacokinetic Principles.)
Chapter 18 Intravenous Anesthetics 1. The rapid onset of the central nervous system (CNS) effects of most intravenous (IV) anesthetics is best explained by their: A. low hepatic extraction ratio B. small volume of distribution C. high lipid solubility D. large ratio of ionized to unionized drug E. slow elimination half-life 1. C. The rapid onset of IV anesthetics is primarily attributable to their high lipid solubility and the relatively high proportion of cardiac output that perfuses the brain. Only the unionized fraction of a drug can cross the blood–brain barrier, so onset is also affected by the pKa of the drug relative to the pH of body fluids; onset is also more rapid when the ratio of unionized to ionized drug is high. Although the volume of distribution, elimination half-life, and hepatic extraction ratio contribute to drug pharmacokinetics, these factors are not primarily responsible for the rapid onset of anesthetic effects. (See page 445: General Pharmacology of Intravenous Hypnotics.) 2. Ketamine interacts with all of the following receptors EXCEPT: A. N-methyl-D-aspartate (NMDA) B. opioid receptors C. γ -Aminobutyric acid (GABA) D. muscarinic receptors E. monoaminergic receptors 2. C. Ketamine interacts with NMDA and opioid, muscarinic, and monoaminergic receptors, but it does not interact with GABA receptors.
This is in contrast to most intravenous anesthetics, which exert their primary effect through GABA receptors. (See page 455: Ketamine.) 3. Which of the following intravenous anesthetic agents has the highest degree of plasma protein binding? A. Thiopental B. Propofol C. Ketamine D. Methohexital E. Etomidate 3. B. Whereas about 98% of propofol is protein bound, about 85% of the barbiturates methohexital and thiopental bind to protein, and 75% of etomidate is protein bound. In contrast, only about 12% of ketamine is protein bound. (See page 447: Pharmacokinetics and Metabolism.) 4. Which of the following has the lowest hepatic extraction ratio? A. Ketamine B. Propofol C. Thiopental D. Midazolam E. Etomidate 4. C. The hepatic extraction ratio is a measure of the rate at which anesthetics are cleared from the systemic circulation by the liver. The hepatic clearance of intravenous anesthetics may be categorized into three groups: high, intermediate, and low. Thiopental, diazepam, and lorazepam have low hepatic extraction ratios, and propofol, etomidate, and ketamine have high hepatic extraction ratios. Methohexital and midazolam have hepatic extraction ratios that are intermediate between these two groups. (See page 447: Pharmacokinetics and Metabolism.) 5. Recovery of cognitive function after general anesthesia is slowest when which of the following agents is used for induction? A. Thiopental
B. Propofol C. Midazolam D. Etomidate E. Ketamine 5. C. In general, benzodiazepines such as midazolam are associated with a relatively prolonged time to recovery of cognitive function compared with other intravenous anesthetics. In contrast, recovery from propofol is usually quite rapid, making it an ideal induction agent for outpatient procedures. Recovery from ketamine, etomidate, and thiopental is intermediate between the benzodiazepines and propofol. (See page 457: Use of Intravenous Anesthetics as Induction Agents.) 6. Concerning the antiemetic effect of propofol, all of the following hypotheses have been postulated EXCEPT: A. It has antidopaminergic activity. B. It has a depressant effect on the chemoreceptor trigger zone. C. It increases the release of glutamate and aspartate in the olfactory cortex. D. It decreases the concentration of serotonin in the area postrema. E. It has a depressant effect on the vagal nucleus. 6. C. Propofol has antidopaminergic activity and depresses the chemoreceptor trigger zone and vagal nucleus. It also decreases the release of glutamate and aspartate in the olfactory cortex and reduces serotonin levels in the area postrema. All of these mechanisms are believed to contribute to propofol's antiemetic properties. (See page 451: Propofol.) 7. Context-sensitive half-time describes: A. the rate of fall of drug concentration at the effect site after discontinuation of continuous infusion B. the rate of decrease in drug concentration in the bloodstream after discontinuation of continuous infusion
C. the rate of decrease of drug concentration in the body after discontinuation of continuous infusion D. the rate of decrease of drug concentration in its volume of distribution after discontinuation of continuous infusion E. the rate of decrease of drug concentration in the liver after discontinuation of continuous infusion 7. A. Context-sensitive half-time is defined as the time necessary for the effect-compartment concentration of drug to decrease by 50% after discontinuation of continuous infusion. (See page 447: Pharmacokinetics and Metabolism.) 8. The involuntary myoclonus seen during induction with etomidate is: A. not associated with cortical seizure activity B. unaffected by prior administration of opioid analgesics C. unaffected by prior administration of benzodiazepines D. extremely uncommon E. best treated with intravenous phenytoin 8. A. A common reaction to induction with etomidate is involuntary myoclonic movements, which occur as a result of subcortical disinhibition. This response is not associated with cortical seizure activity and may be attenuated by prior administration of opioid analgesics or benzodiazepines. The use of antiseizure drugs such as phenytoin is not indicated. (See page 454: Etomidate.) 9. Rank the following induction agents in order of their degree of cardiovascular depression. A. Propofol > Etomidate > Thiopental B. Thiopental > Propofol > Etomidate C. Propofol > Thiopental > Etomidate D. Etomidate > Thiopental > Propofol E. Thiopental > Etomidate > Propofol
P
9. C. The cardiovascular effects of propofol are more profound than those of thiopental or etomidate. Etomidate is the induction agent considered to have the least impact on the cardiovascular system. (See page 450: Comparative Physiochemical and Clinical Pharmacologic Properties.) 10. Which of the following statements concerning the mechanisms of action of intravenous induction agents is NOT true? A. Barbiturates appear to increase the duration of γ aminobutyric acid (GABA)-activated opening of chloride ion channels. B. Benzodiazepines appear to increase the efficiency of coupling between GABA receptors and chloride ion channels. C. Ketamine produces dissociative amnesia through interaction with N-methyl-D-aspartic acid (NMDA) receptors. D. Thiopental appears to act as a competitive inhibitor at central nicotinic acetylcholine (Ach) receptors. E. Propofol appears to have a mechanism of action similar to that of the benzodiazepines. 10. E. Propofol appears to increase the duration of GABA-mediating chloride channel opening. Therefore, its mechanism of action is most similar to that of the barbiturates, not the benzodiazepines. However, benzodiazepines also act via the GABA receptor, increasing the efficiency of coupling between the GABA receptor and chloride ion channels. Whereas thiopental is believed to exert its effect via competitive inhibition of nicotinic Ach receptors in the central nervous system, ketamine acts via NMDA receptors. (See page 445: General Pharmacology of Intravenous Hypnotics.) 11. Which of the following is NOT a typical induction regimen for a healthy adult patient? A. Etomidate, 0.3 to 0.6 mg/kg B. Ketamine, 0.5 to 1.0 mg/kg C. Methohexital, 3 to 5 mg/kg D. Midazolam, 0.1 to 0.2 mg/kg
E. Propofol, 1.5 to 2.5 mg/kg 11. C. The typical induction dose of methohexital is 1.0 to 1.5 mg/kg intravenously. All of the other choices represent typical induction drug dosages. (See page 450: Comparative Physiochemical and Clinical Pharmacologic Properties.) 12. Ketamine is associated with all of the following physiologic effects EXCEPT: A. bronchodilation B. elevation of intracranial pressure C. decreased oral secretions D. sympathetic stimulation E. increased pulmonary artery pressure 12. C. Ketamine is a sympathetic stimulant that increases peripheral arteriolar resistance, arterial blood pressure, heart rate, and pulmonary artery pressure. It also possesses bronchodilatory activity. In contrast to the other commonly used intravenous induction agents, ketamine increases cerebral blood flow, cerebral metabolic oxygen demand, and intracranial and intraocular pressures. Ketamine also increases oral secretions. Therefore, pretreatment with an antisialogogue is sometimes useful. (See page 455: Ketamine.) 13. Which of the following induction agents may facilitate the interpretation of somatosensory evoked potentials (SSEPs)? A. Ketamine B. Propofol C. Methohexital D. Midazolam E. Etomidate 13. E. Etomidate increases the amplitude of SSEPs and can be useful in the interpretation of SSEPs when signal quality is poor. (See page 454: Etomidate.)
14. For which of the following patients would ketamine be LEAST appropriate as an induction agent? A. A 39-year-old woman with acute asthma exacerbation who is undergoing emergency appendectomy B. A 70-year-old woman with cardiac tamponade who is undergoing emergency thoracotomy C. A 50-year-old woman with glaucoma who is scheduled for elective cataract resection D. A 55-year-old man with mild renal insufficiency who is undergoing sigmoid resection for diverticulitis E. A 7-year-old child without intravenous access who is scheduled for elective tonsillectomy 14. C. Ketamine increases intraocular pressure and is therefore not an appropriate induction agent in patients with glaucoma. Ketamine is a sympathetic stimulant that has bronchodilatory effects. These properties make it a useful agent in a carefully defined subset of patients, such as those with acute bronchospasm, hypovolemic shock, right-to-left intracardiac shunts, and cardiac tamponade. However, its sympathomimetic effects may be ineffective in the context of maximal sympathetic output. Ketamine may be delivered intramuscularly in patients without intravenous access. (See page 455: Ketamine.) 15. Which of the following intravenous (IV) induction agents produces dissociative anesthesia? A. Propofol B. Etomidate C. Thiopental D. Ketamine E. Midazolam 15. D. Ketamine produces dose-dependent central nervous system depression leading to a so-called dissociative anesthetic state characterized by profound analgesia and amnesia, even though patients may be conscious and maintain protective reflexes. The proposed mechanism for this cataleptic state includes electrophysiologic inhibition
of thalamocortical pathways and stimulation of the limbic system. None of the other IV anesthetic agents produce a dissociative anesthetic state. (See page 455: Ketamine.) 16. Which of the following intravenous induction agents has metabolites that are pharmacologically inactive? A. Diazepam B. Ketamine C. Propofol D. Thiopental E. Midazolam 16. C. Propofol is rapidly and extensively metabolized to inactive, water-soluble sulphate and glucuronic acid metabolites, which are eliminated by the kidneys. Midazolam undergoes extensive oxidation by hepatic enzymes to form water-soluble hydroxylated metabolites, which are excreted in the urine. However, the primary metabolite, 1hydroxymethylmidazolam, has mild central nervous system (CNS) depressant activity. Diazepam is metabolized to active metabolites (desmethyldiazepam, 3-hydroxydiazepam), which can prolong diazepam's residual sedative effects because of their long t½β values. Thiopental is metabolized in the liver to hydroxythiopental and the carboxylic acid derivative, which are more water soluble and have little CNS activity. When high doses of thiopental are administered, a desulfuration reaction may occur with the production of pentobarbital, which has long-lasting CNS depressant activity. Ketamine is metabolized into norketamine, which is also pharmacologically active. (See page 448: Pharmacodynamic Effects.) 17. Flumazenil is an antagonist of which of the following intravenous (IV) induction agents? A. Ketamine B. Propofol C. Midazolam D. Methohexital
E. Etomidate 17. C. In contrast to all other sedative–hypnotic drugs, there is a specific antagonist for benzodiazepines. Flumazenil, a 1,4imidazobenzodiazepine derivative, has a high affinity for the benzodiazepine receptor but minimal intrinsic activity. Flumazenil acts as a competitive antagonist in the presence of benzodiazepine agonist compounds. Flumazenil is short acting, with an elimination half-life of approximately 1 hour. Recurrence of the central effects of benzodiazepines (resedation) may occur after a single dose of flumazenil because of the more slowly eliminated agonist drug. If sustained antagonism is desired, it may be necessary to administer flumazenil as repeated doses or by a continuous infusion. In general, 45 to 90 minutes of antagonism can be expected after 1 to 3 mg of flumazenil IV. However, the respiratory depression produced by benzodiazepines is not completely reversed by flumazenil. Reversal of benzodiazepine sedation with flumazenil is not associated with adverse cardiovascular effects or evidence of an acute stress response. (See page 453: Benzodiazepines.) 18. Which of the following intravenous (IV) induction agents is associated with least respiratory depression? A. Ketamine B. Propofol C. Thiopental D. Etomidate E. Lorazepam 18. A. With the exception of ketamine (and to a lesser extent, etomidate), IV anesthetics produce dose-dependent respiratory depression, which is enhanced in patients with chronic obstructive pulmonary disease. Ketamine causes minimal respiratory depression in clinically relevant doses and can facilitate the transition from mechanical to spontaneous ventilation after anesthesia. In contrast to the other IV anesthetics, protective airway reflexes are more likely to be preserved with ketamine. The respiratory depression is characterized by a decrease in tidal volume and minute ventilation, as well as a transient rightward shift in the CO2 response curve. After the rapid
injection of a large bolus dose of an IV anesthetic, transient apnea lasting 30 to 90 seconds is usually produced. (See page 455: Ketamine.) 19. Which of the following intravenous (IV) anesthetics is considered to be the most immunologically “safe?” A. Ketamine B. Etomidate C. Propofol D. Midazolam E. Methohexital 19. B. Severe anaphylactic reactions to IV anesthetics are extremely uncommon; however, profound hypotension attributed to nonimmunologically mediated histamine release has been reported with thiopental use. Although anaphylactic reactions to etomidate have been reported, it does not appear to release histamine and is considered to be the most “immunologically safe” IV anesthetic. Although propofol does not normally trigger histamine release, life-threatening anaphylactoid reactions have been reported in patients with a previous history of multiple drug allergies. With the exception of etomidate, all IV induction agents have been alleged to cause some histamine release. (See page 450: Hypersensitivity Reactions.) 20. Which of the following intravenous (IV) induction agents is contraindicated in patients who are predisposed to acute intermittent porphyria? A. Lorazepam B. Ketamine C. Etomidate D. Thiopental E. Propofol 20. D. Barbiturates can precipitate episodes of acute intermittent porphyria, so their use is contraindicated in patients who are predisposed to acute intermittent porphyria. Although the benzodiazepines, ketamine, and etomidate are reported to be safe in
humans, these drugs have been shown to be porphyrogenic in animal models. Propofol is not contraindicated in patients who are predisposed to acute intermittent porphyria. (See page 448: Pharmacodynamic Effects.) 21. Which of the following intravenous (IV) induction agents may produce adverse effects when administered in the presence of tricyclic antidepressants (TCAs)? P A. Etomidate B. Midazolam C. Thiopental D. Ketamine E. Lorazepam 21. D. Ketamine can produce adverse effects when administered in the presence of TCAs because both drugs inhibit norepinephrine reuptake and may produce severe hypotension, heart failure, or myocardial ischemia. None of the other IV induction agents produces these effects when given in the presence of TCAs. (See page 455: Ketamine.) For questions 22 to 32, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 22. Which of the following factor(s) contribute(s) to the hemodynamic changes associated with intravenous (IV) induction of anesthesia? 1. Pre-existing cardiovascular and fluid status 2. Resting sympathetic nervous system tone 3. Preanesthetic medication 4. Speed of drug injection 22. E. Many different factors contribute to the hemodynamic changes associated with IV induction of anesthesia, including the patient's preexisting cardiovascular and fluid status, the resting sympathetic nervous system tone, chronic cardiovascular drug use, use of preanesthetic
medications, the speed of drug injection, and the onset of unconsciousness. In addition, cardiovascular changes can be attributed to the direct pharmacologic actions of anesthetic and analgesic drugs on the heart and peripheral vasculature. IV anesthetics can depress the central nervous system and peripheral nervous system responses, blunt the compensatory baroreceptor reflex mechanisms, produce direct myocardial depression, and lower peripheral vascular resistance (or dilate venous capacitance vessels), thereby decreasing venous return. Profound hemodynamic effects occur at induction of anesthesia in the presence of hypovolemia because a higher than expected drug concentration is achieved in the central compartment. Not surprisingly, the acute cardiocirculatory depressant effects of all IV anesthetics are accentuated in elderly individuals and in the presence of pre-existing cardiovascular disease (e.g., coronary artery disease, hypertension). (See page 448: Pharmacodynamic Effects.) 23. TRUE statements about the use of propofol for sedation include: 1. It produces more reliable amnesia than midazolam. 2. It has little effect on hypoxic ventilatory response. 3. It is the drug of choice for patients with hemodynamic instability. 4. It allows for relatively rapid transitions from deeper to lighter levels of anesthesia. 23. D. Propofol is associated with relatively rapid recovery, facilitating transitions from deeper to lighter levels of anesthesia. In the intensive care unit setting, when compared with midazolam, propofol sedation has been associated with more rapid weaning from artificial ventilation. However, propofol produces less reliable amnesia and more pain on injection than midazolam. In addition, even at low concentrations, propofol depresses the normal hypoxic ventilatory response, so supplemental oxygen should always be used in conjunction with propofol sedation. (See page 451: Propofol.) 24. Which of the following statements concerning the pharmacology of intravenous (IV) induction agents is/are TRUE?
1. At typical clinical concentrations, the rate of drug elimination is described by zero-order kinetics. 2. Termination of initial central nervous system effects is primarily the result of drug redistribution. 3. At high steady-state plasma concentrations, the rate of drug elimination decreases as the exponential function of the drug's plasma concentration. 4. They typically undergo hepatic metabolism followed by renal excretion. 24. C. Termination of the central effects of intravenous anesthetics is primarily related to redistribution from the brain rather than elimination from the body. Most IV agents undergo hepatic metabolism into watersoluble compounds that are then excreted by the kidneys. At typical clinical concentrations, the rate of drug elimination decreases as the exponential function of the drug's plasma concentration—so-called firstorder kinetics. However, at high steady-state concentrations, the rate of drug elimination becomes independent of drug concentration resulting from saturation of enzymes responsible for their metabolism (zero-order kinetics). (See page 447: Pharmacokinetics and Metabolism.) 25. Which of the following statements concerning intravenous (IV) anesthetic agents in elderly patients compared with younger adults is/are TRUE? 1. Redistribution from vessel-rich tissue compartments is slower. 2. The steady-state volume of distribution is reduced. 3. The rate of hepatic clearance is reduced. 4. There is a decreased volume of the central compartment. 25. E. Elderly patients have increased steady-state volume of distribution for most IV anesthetics and decreased hepatic clearance, leading to prolongation of their β half-life values. They also have decreased volume of the central compartment and slower redistribution from vessel-rich tissue to intermediate compartments. As a result, the dose of anesthetic required to elicit effect is lower and the time to recovery is longer in elderly patients than in younger patients. (See page 447: Pharmacokinetics and Metabolism.)
26. Which of the following statements concerning methohexital is/are TRUE? 1. It is an oxybarbiturate. 2. It is associated with a more profound degree of hypotension compared with thiopental. 3. It can be used to evoke epileptic activity in patients with temporal lobe epilepsy. 4. It is approximately one third as potent as thiopental. 26. B. Methohexital is an oxybarbiturate that is two to three times more potent than thiopental. Compared with thiopental, it produces a relatively more robust tachycardic response, leading to a lesser degree of hypotension. Methohexital can produce epileptiform electroencephalographic (EEG) activity and is used to activate cortical EEG seizure discharges in patients with temporal lobe epilepsy. (See page 450: Barbiturates.) 27. Accidental intra-arterial injection of barbiturates is commonly treated with: 1. intra-arterial administration of papaverine 2. intra-arterial administration of lidocaine 3. heparinization 4. tourniquet application to the affected limb 27. A. Treatments for accidental intra-arterial injection of thiobarbiturates include intra-arterial administration of papaverine and/or lidocaine, heparinization, and/or regional anesthesia–induced sympathectomy. Isolation of regional blood flow via tourniquet application is not appropriate. (See page 450: Barbiturates.) 28. Concerning propofol, which of the following statements is/are TRUE? 1. It is a reasonable induction agent for patients susceptible to malignant hyperthermia. 2. It can be used safely in patients with a history of acute intermittent porphyria.
3. It can be used to decrease pruritus associated with administration of intrathecal opioids. 4. Its effects are usually prolonged in patients with pre-existing hepatic disease. 28. A. Propofol is a reasonable induction agent in patients who are susceptible to malignant hyperthermia, and it can be used safely in patients with acute intermittent porphyria. Propofol also decreases pruritus associated with intrathecal opioid use and cholestatic liver disease. Even though propofol is metabolized by the liver, its effects are generally not prolonged in patients with pre-existing hepatic disease. (See page 451: Propofol.) 29. Which of the following statements concerning etomidate is/are TRUE? 1. It does not stimulate histamine release. 2. It induces involuntary myoclonic movements, which can be attenuated by prior administration of opioid analgesics. 3. It is associated with a high incidence of postoperative nausea and vomiting. 4. A single induction dose does not cause any measurable adrenal suppression. 29. A. Etomidate sometimes induces nonepileptogenic involuntary myoclonus during induction that can be attenuated by the preinduction use of an opioid analgesic. In addition, it is associated with a high incidence of postoperative nausea and vomiting and has been shown to depress adrenocortical function for several hours after a single induction dose. Etomidate does not induce histamine release and can be safely used in patients with reactive airway disease. (See page 454: Etomidate.) 30. Which of the following statements concerning the cardiovascular effects of propofol is/are TRUE? 1. It causes arterial dilation. 2. It increases peripheral venous pooling. 3. It impairs the baroreceptor reflex response.
4. It is not a direct myocardial depressant. 30. A. Propofol causes arterial and venous dilatation as well as impairment of the baroreceptor reflex, all of which contribute to a decrease in systemic arterial pressure. In addition, propofol has myocardial depressant effects. All of these factors contribute to the decrease in systemic arterial pressure commonly observed after propofol induction. These cardiovascular effects are more profound than those associated with thiopental or etomidate. (See page 451: Propofol.) 31. Which of the following statements regarding the structure and metabolism of intravenous induction agents is/are correct? 1. Pentobarbital is a potential metabolite of thiopental that can cause long-lasting central nervous system (CNS) depressant activity. 2. Thiopental solution (2.5%) is highly acidic. 3. The hydroxyl derivative of methohexital is inactive. 4. The analgesic and anesthetic potency of the S(+) isomer of ketamine is less than that of the racemic mixture. 31. B. Thiopental is metabolized in the liver to hydroxythiopental and a carboxylic acid derivative. However, at high doses, thiopental undergoes a desulfuration reaction that leads to the production of pentobarbital, a compound associated with long-lasting CNS depression. Methohexital is metabolized in the liver to inactive hydroxyderivates. Thiopental is available in a 2.5% solution that is highly alkalotic (pH >9), and as such, inadvertent extravenous injection causes tissue irritation. The anesthetic and analgesic potency of the S(+) isomer of ketamine is greater than that of the racemic mixture. (See page 450: Comparative Physiochemical and Clinical Pharmacologic Properties.) 32. Which of the following intravenous agents has intrinsic analgesic properties? 1. Ketamine 2. Dexmedetomidine 3. Clonidine 4. Thiopental
32. A. Ketamine, dexmedetomidine, and the α 2 agonist clonidine appear to possess analgesic properties. In contrast, thiopental appears to have a mild antianalgesic effect. (See page 448: Pharmacodynamic Effects.)
Chapter 19 Opioids 1. All of the following statements regarding opioid–receptor interactions are true EXCEPT: A. The analgesic effects of opioids are thought to result primarily from the activation of μ receptors in the brain and spinal cord. B. Opioid–receptor activation in peripheral tissues may play a role in the modulation of painful stimuli. C. Naloxone is highly specific for the μ subtype of opioid receptors. D. Most opioids clinically used are highly selective for the μ subtype opioid receptor. E. Opioid receptors are coupled to G proteins that regulate the activity of adenylate cyclase. 1. C. Most observed opioid effects involve interactions with receptor systems at spinal and supraspinal sites, although clinical studies suggest that morphine can produce analgesia by peripheral mechanisms, especially when inflammation is present. Whereas the intrinsic activity, or efficacy, of an opioid is described by the dose–response curve resulting from drug–receptor interaction, affinity describes the ability of a drug to bind a receptor to produce a stable complex. Most opioids used in current clinical practice are highly selective for μ receptors, but naloxone, the most commonly used opioid antagonist, is not selective for opioid receptor type. For this reason, identification of an opioid receptor–mediated drug effect requires demonstration of naloxone reversibility. (See page 466: Endogenous Opioids and Opioid Receptors.) 2. The ability of an opioid to cross the blood–brain barrier depends on all of the following properties EXCEPT: A. lipid solubility B. ionization
C. protein binding D. μ activity E. molecular size 2. D. Physicochemical properties of the opioids influence both pharmacokinetics and pharmacodynamics. To reach its effector sites in the central nervous system (CNS), an opioid must cross biologic membranes from the blood to receptors on neuronal cell membranes. The ability of opioids to cross this blood–brain barrier depends on such properties as molecular size, ionization, lipid solubility, and protein binding (see Table 19-2). Of these characteristics, lipid solubility and ionization assume major importance in determining the rate of penetration to the CNS. (See page 468: Pharmacokinetics and Pharmacodynamics.) 3. Which of the following statements regarding opioid-induced muscle rigidity is/are TRUE? A. Muscle rigidity does not occur with morphine doses below 0.2 mg/kg. B. The phenomenon is seen only on induction of anesthesia without the use of neuromuscular blocking agents. C. Muscle rigidity is reduced by the addition of nitrous oxide. D. The effects are eliminated by naloxone. E. Opioid-induced muscle rigidity is mediated by σ receptors. 3. D. Large doses of opioids may produce profound muscle rigidity, an effect that appears to be mediated by μ receptors at supraspinal sites, most notably the nucleus raphe pontis and sites lateral to it in the hindbrain. Such muscle rigidity is most often witnessed on induction with large doses of opioids, although postoperative occurrences have been observed, as have feelings of muscle tension after small doses (10–15 mg) of morphine. Opioid-induced muscle rigidity is drastically increased by the addition of 70% nitrous oxide, but it is reduced or eliminated by naloxone, drugs that facilitate γ -aminobutyric acid agonist activity, and muscle relaxants. (See page 469: Morphine: Muscle Rigidity.)
4. Which of the following routes of opioid administration reliably reduces the incidence of opioid-induced nausea? A. Intramuscular B. Intrathecal C. Subcutaneous D. Transdermal E. None of the above 4. E. Opioid-induced nausea is thought to be a result of input to the vomiting center from stimulation of the chemotactic trigger zone in the area postrema of the medulla, which is rich in opioid receptors. Not only does the incidence of opioid-induced nausea appear to be irrespective of the route of administration, but clinical studies also reveal no differences among opioid species, including morphine, meperidine, fentanyl, sufentanil, and alfentanil. (See page 469: Morphine: Nausea and Vomiting.) 5. A 46-year-old man with a history of multiple uneventful general anesthetics is undergoing a spinal fusion procedure during which 1 mg/kg of morphine is administered over 15 minutes. Shortly thereafter, the patient exhibits modest hypotension with a concomitant decrease in systemic vascular resistance, as well as an increase in pulmonary vascular resistance as measured by a pulmonary artery catheter. These findings are unaffected by the administration of 0.2 mg of naloxone. The most likely cause of this clinical constellation is: A. morphine-induced histamine release B. a previously undiagnosed anaphylaxis C. an opioid-mediated increase in vascular permeability D. the central vagotonic effects of morphine E. direct myocardial depression by morphine 5. A. Opioids stimulate the release of histamine from mast cells and basophils in a dose-dependent manner, an effect seen commonly after high doses of morphine. Decreases in peripheral vascular resistance and corresponding increases in pulmonary vascular resistance after morphine
administration have been shown to correlate well with elevated plasma histamine concentrations. Opioid-induced histamine release is not prevented by pretreatment with naloxone, a finding suggesting a mechanism independent of opioid receptor activation. In clinically relevant doses, morphine does not depress myocardial contractibility. It does, however, produce dose-dependent bradycardia, probably by both sympatholytic and parasympathomimetic mechanisms. (See page 469: Morphine: Histamine Release.) 6. The occurrence of myoclonic activity and seizures observed after repeated or prolonged administration of meperidine is most likely the result of: A. direct central nervous system (CNS) effects resulting from the inherent local anesthetic actions of meperidine B. direct CNS excitation by meperidine C. neurotoxic effects of normeperidine, an active metabolite of meperidine D. insidious hypoxemia as a consequence of the prolonged clinical half-life of meperidine E. selective activation of spinal κ receptors with increasing serum levels of meperidine 6. C. Meperidine is metabolized primarily in the liver by N-methylation to form normeperidine, an active metabolite, and to a lesser extent by hydrolysis to form meperidinic acid. In humans, CNS effects such as restlessness, agitation, tremors, myoclonus, and seizures have been associated with increased serum levels of normeperidine. Normeperidine, which has a considerably longer elimination half-life than its parent compound, is more apt to accumulate with repeated or prolonged administration of meperidine or in patients with renal dysfunction. (See page 473: Meperidine: Active Metabolites.) 7. Which physical characteristic of fentanyl best accounts for its rapid onset of clinical effect as well as its brief duration of action? A. High lipid solubility B. High degree of ionization
C. Relatively small molecular weight D. Negligible protein binding E. Low hepatic clearance 7. A. Fentanyl's high degree of lipid solubility enables it to cross biologic membranes very rapidly and to permeate highly perfused tissue groups, such as the brain, heart, and lung. This same characteristic accounts for the relatively brief clinical duration of effect seen with fentanyl because redistribution of the drug to other tissues, including muscle and fat, also results from high lipid solubility. Similarly, accumulation of fentanyl in such tissue compartments can be extensive with prolonged administration, thus creating “reservoirs” of drug. (See page 476: Fentanyl: Disposition Kinetics.) 8. Regarding methadone, which of the statements below is FALSE? A. Methadone is primarily a μ agonist. B. After parenteral administration, the onset of analgesia is within 20 minutes. C. Methadone is not well absorbed orally, with only 10% bioavailability. D. Methadone reaches peak plasma concentration four hours after oral administration. E. Methadone is nearly 90% protein bound. 8. C. Methadone, a synthetic opioid introduced in the 1940s, is primarily a μ agonist with pharmacologic properties that are similar to morphine. Although its chemical structure is very different from that of morphine, steric factors force the molecule to simulate the pseudopiperidine ring conformation that appears to be required for opioid activity. Methadone is well absorbed after an oral dose, with bioavailability approximately 90%, and reaches peak plasma concentration at 4 hours after oral administration. Because of its long elimination half-life, methadone is most often used for long-term pain management and for treatment of opioid abstinence syndromes. After parenteral administration, the onset of analgesia is within 10 to 20 minutes. After a single dose up to 10 mg, the duration of analgesia is similar to morphine, but with large or
P
repeated parenteral doses, prolonged analgesia can be obtained. It is nearly 90% bound to plasma proteins. (See page 475: Methadone.) 9. All of the following statements regarding clinical characteristics of alfentanil are true EXCEPT: A. On a milligram basis, the clinical potency of alfentanil is roughly 10 times that of morphine and one tenth that of fentanyl. B. Alfentanil displays a significantly faster onset of action than fentanyl and sufentanil. C. Alfentanil has a longer terminal half-life than fentanyl and sufentanil. D. The incidence of nausea and vomiting associated with alfentanil is no higher than that with either fentanyl or sufentanil. E. Similar to fentanyl and sufentanil, alfentanil may produce profound muscle rigidity when it is given in high doses. 9. C. Alfentanil is a synthetic tetrazole derivative of fentanyl with a clinical potency nearly 10 times that of morphine and one fourth to one tenth that of fentanyl. Alfentanil is a weaker base than other opioids, with a pKa of 6.8. As such, nearly 90% of unbound plasma alfentanil is nonionized at physiologic pH. This property, in addition to its moderately high lipid solubility, allows alfentanil to cross the blood–brain barrier rapidly and accounts for its rapid onset of action. Alfentanil has a terminal elimination half-life of 84 to 90 minutes, considerably shorter than that of fentanyl or sufentanil, mainly because of its relatively small volume of distribution. The incidences of clinical side effects with alfentanil have been shown to be similar to those with fentanyl and sufentanil when compared at equianalgesic doses. Early reports of a higher incidence of nausea and vomiting with alfentanil have not been substantiated. (See page 482: Alfentanil.) 10. Remifentanil exhibits a markedly shorter clinical duration of action compared with other commonly used opioids because of: A. rapid redistribution resulting from high lipid solubility B. a lesser degree of opioid receptor affinity
C. a high protein-bound (α 1-acid glycoprotein) fraction D. a relatively high volume of distribution E. metabolism of an ester side chain by blood and tissue esterases 10. E. Remifentanil is a recently synthesized 4-anili-dopiperidine opioid with a methyl ester side chain that is susceptible to metabolism by blood and tissue esterases. A unique property of remifentanil compared with other clinically useful opioids is its lack of accumulation with repeated dosing or prolonged infusion. This is because its ultrashort duration of action is the result of metabolism to a substantially less active compound, rather than simply redistribution of an unchanged opioid. (See page 484: Remifentanil.) 11. Which of the following statements regarding sufentanil is TRUE? A. It has a clinical potency 100 to 200 times that of morphine. B. Bradycardia is usually not seen when pancuronium is used during anesthesia with sufentanil. C. Sufentanil has a higher volume of distribution than fentanyl because of its decreased plasma protein binding. D. Approximately 60% of an intravenous (IV) bolus dose of sufentanil is cleared from the plasma in 90 minutes. E. Sufentanil is extremely hydrophilic. 11. B. Sufentanil has a clinical potency ratio 2000 to 4000 times that of morphine. It is extremely lipophilic. Combining vecuronium and sufentanil may cause a decrease in mean arterial pressure during induction, and significant bradycardia and sinus arrest have been reported. Bradycardia is not seen when pancuronium is used during anesthesia with sufentanil. Because of a smaller degree of ionization at physiologic pH and higher degree of plasma protein binding, its volume of distribution is somewhat smaller and its elimination half-life is shorter than those of fentanyl. Plasma sufentanil concentration decreases very rapidly after an IV bolus dose, and 98% of the drug is cleared from plasma within 30 minutes. (See page 478: Cardiovascular and Endocrine Effects.) 12. Which of the following characteristics of remifentanil is FALSE?
A. Remifentanil is about 40 times more potent than alfentanil. B. Remifentanil is devoid of muscle rigidity side effects because of its rapid metabolism. C. Remifentanil has less depressant effect on motor evoked potentials than other opioids. D. Remifentanil is associated with poor postoperative pain control if it is used intraoperatively because of its rapid metabolism. E. Shivering is more common with remifentanil than with alfentanil. 12. C. Nalbuphine is a partial opioid agonist at both κ and μ receptors. Administered alone, partial agonists exhibit a more shallow dose– response curve and lower maximal effects than full agonists. The respiratory depression produced by nalbuphine has a ceiling effect equivalent to that produced by 30 mg/70 kg of morphine. Because of this, nalbuphine has been used to antagonize the adverse effects of other opioids while still providing analgesic effects. Indeed, nalbuphine has been shown to be as effective as full μ agonists in providing postoperative analgesia in some instances. However, there is still the potential for respiratory depression. As an opioid agonist–antagonist, nalbuphine may precipitate withdrawal symptoms in patients who are dependent on opioids. (See page 488: Partial Agonist and Mixed Agonist– Antagonists: Nalbuphine.) 13. All of the following statements regarding nalbuphine are true EXCEPT: A. The analgesic properties of nalbuphine exhibit a ceiling effect. B. In some instances, nalbuphine can be as effective as full μ agonists in providing postoperative analgesia. C. Significant respiratory depression is not seen with nalbuphine. D. Nalbuphine may be used to antagonize the respiratory depressant effects of another opioid while still providing analgesia. E. Nalbuphine may precipitate withdrawal symptoms in patients who are physically dependent on opioids.
13. B. Remifentanil is about 40 times as potent as alfentanil. A high incidence of muscle rigidity and purposeless movement has been seen with remifentanil. Although all opioids and propofol depress motor evoked potentials in a dose-dependent fashion, remifentanil exerts less suppression than other opioids and propofol. One drawback of remifentanil use for general anesthesia is that patients require analgesics soon after an infusion is stopped. Shivering is less common with alfentanil than with remifentanil. (See page 484: Remifentanil.) 14. Which of the following statements regarding opioid-induced nausea and vomiting is TRUE? A. Equipotent doses of opioids cause an equal incidence of nausea and vomiting. B. Morphine has no direct effect on the chemoreceptor trigger zone. C. Subcutaneous administration of opioids is associated with a lower incidence of nausea and vomiting compared with intravenous (IV) administration. D. Vestibular stimulation such as ambulation attenuates the nausea caused by morphine. E. All of the above 14. A. The incidence of opioid-induced nausea appears to be similar irrespective of the route of administration (including oral, IV, intramuscular, subcutaneous, transmucosal, transdermal, intrathecal, and epidural). Laboratory and clinical studies comparing the incidence and severity of nausea and vomiting have found no differences among opioids (including morphine, hydromorphone, meperidine, fentanyl, sufentanil, alfentanil, and remifentanil) in equianalgesic doses. (See page 469: Morphine: Nausea and Vomiting.) For questions 15 to 21, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 15. Which of the following statements regarding morphine-induced pupillary constriction (miosis) in humans is/are TRUE?
1. The presence of miosis correlates with opioid-induced respiratory depression. 2. The effect is thought to be mediated via the nucleus tractus solitarius of the oculomotor nerve. 3. A near-maximal degree of miosis is seen with as little as 0.5 mg/kg of morphine. 4. The absence of miosis virtually eliminates opioids as a cause of respiratory depression. 15. B. Morphine produces dose-dependent miosis in humans, an effect that is believed to be mediated by the Edinger-Westphal nucleus of the third cranial nerve. Although significant differences exist between opioid species and their effects on pupillary size, morphine produces a near-maximal degree of constriction with 0.5 mg/kg. In the absence of other drugs, the resultant miosis appears to correlate with opioidinduced respiratory depression, although severe hypoxemia may result in pupillary dilation. (See page 469: Morphine: Other Central Nervous System Effects.) P 16. The chemoreceptor trigger zone (CTZ) in the area posterior of the medulla is rich in which receptors? 1. Opioid 2. Dopamine 3. Histamine 4. Serotonin 16. E. The CTZ is rich in opioid, dopamine, serotonin, histamine, and (muscarinic) acetylcholine receptors and receives input from the vestibular portion of the eighth cranial nerve. Morphine and related opioids induce nausea by direct stimulation of the CTZ and can also produce increased vestibular sensitivity. (See page 471: Nausea and Vomiting.) 17. The clinical effects of meperidine that differ from those observed with other commonly used opioids include: 1. absence of histamine release from tissue mast cells
2. decrease in cardiac contractility after high doses 3. less nausea and vomiting at equianalgesic doses 4. direct local anesthetic effects 17. C. Meperidine is a synthetic opioid with an analgesic potency about one tenth that of morphine. Although the analgesic effects are primarily mediated via μ receptor activation, meperidine has demonstrated local anesthetic properties, which has led to its increasing popularity for epidural and subarachnoid administration. This local anesthetic effect is thought to be responsible for decreases in cardiac contractility observed with high plasma concentrations of meperidine, a finding not consistent with other clinically used opioids. Meperidine administration does result in histamine release, an effect that may contribute to the hemodynamic instability often encountered when high doses are used in the clinical setting. At equianalgesic doses, the respiratory depression caused by meperidine is no different from that induced by morphine, hydromorphone, meperidine, fentanyl, sufentanil, alfentanil, or remifentanil. (See page 473: Meperidine: Side Effects.) 18. Common potential disadvantages of a high-dose opioid anesthetic technique using fentanyl as the sole agent for anesthesia include: 1. hemodynamic instability and cardiac depression 2. impaired ventilation resulting from intense chest wall muscle rigidity 3. prolonged anterograde amnesia 4. the need for protracted postoperative ventilatory support 18. C. High-dose opioid-based anesthetic techniques, particularly those using synthetic opioids (e.g., fentanyl), initially gained popularity because of the reliable hemodynamic stability that is achieved with minimal cardiovascular depression. In addition, hormonal responses to surgical stimuli are significantly blunted with such a regimen. Notable disadvantages include prolonged respiratory depression, a high incidence of clinically significant muscle rigidity on induction, and frequent reports of intraoperative awareness and recall when opioids are used as the sole anesthetic agent. (See page 476: Fentanyl: Use in Anesthesia.)
19. Characteristics of buprenorphine include: 1. it does not appear to have agonist activity at the κ -opioid receptor 2. at small to moderate doses, it is 25 to 50 times more potent than morphine 3. at very high doses, it produces progressively less analgesia 4. the maximum naloxone antagonist effect may not occur until 3 hours after naloxone administration because of buprenorphine's slow dissociation from μ receptors 19. E. Buprenorphine is a highly lipophilic thebaine derivative and is a partial μ -opioid agonist. At small to moderate doses, it is 25 to 50 times more potent than morphine. Unlike nalbuphine and butorphanol, buprenorphine does not appear to have agonist activity at the κ -opioid receptor. Another unique characteristic of buprenorphine is its slow dissociation from μ receptors, which may lead to prolonged effects not easily antagonized by naloxone. Buprenorphine also appears to have an unusual bell-shaped dose–response curve such that at very high doses, it produces progressively less analgesia. (See page 490: Buprenorphine.) 20. Potential disadvantages to use remifentanil as a component to a balanced anesthetic technique include: 1. prolonged respiratory depression with infusion techniques resulting from accumulation of active metabolites 2. ultrashort duration of analgesic effect 3. a single dose of 20 μg/kg reliably produces unconsciousness when used for induction 4. intraoperative muscle rigidity 20. C. Remifentanil is rapidly metabolized by blood and tissue esterases to a substantially less active compound. The duration of the respiratory depression seen with remifentanil has been shown to parallel the duration of its analgesic effects. The side effects of remifentanil, including a high incidence of muscle rigidity with high doses, are similar to those of other commonly used opioids at equianalgesic doses. Although an ultrashort duration of action makes remifentanil an
appealing agent for opioid infusion techniques and ease of titration, this characteristic poses a potential disadvantage because patients may require additional analgesics very soon after remifentanil is discontinued. Loss of consciousness is not reliably achieved with remifentanil alone. (See page 484: Remifentanil.) 21. Potential hazards in the use of naloxone to reverse opioidinduced respiratory depression include: 1. sudden, severe pain in postoperative patients 2. precipitation of withdrawal syndromes in patients who are physically dependent on opioids 3. late respiratory depression 4. acute pulmonary edema 21. E. Naloxone is a pure opioid antagonist at μ, κ, and δ opioid receptors that is used most often in clinical practice to antagonize opioid-induced respiratory depression and sedation. Because naloxone antagonizes all opioid–receptor interactions, it interrupts μ - and κ receptor–mediated analgesia and may lead to severe pain. In some instances, acute, and sometimes fatal, pulmonary edema may ensue, an effect that is believed to result from a centrally mediated catecholamine release causing acute pulmonary hypertension. Because the duration of clinical effect seen with naloxone ranges from 1 to 4 hours, it is possible for renarcotization to occur when pre-existing opioids reactivate receptors after the effects of naloxone have subsided. (See page 490: Opioid Antagonists [Naloxone and Naltrexone].)
Chapter 20 Neuromuscular Blocking Agents 1. All of the following statements regarding a peripheral nerve are true EXCEPT: A. It is made up of a large number of axons of different threshold potentials. B. Each axon responds in an all-or-none fashion to a given stimulus. C. When a stimulating current reaches a high enough level, all axons are activated, and the amplitude of the action potential reaches a maximum level. D. There is a linear relationship between the amplitude of the muscle contraction and the current applied. E. Sodium channels in the nerve axon are activated in response to electrical stimulation. 1. D. A peripheral nerve is made up of a large number of axons of different thresholds and sizes. Each axon responds in an all-or-none fashion, but not all axons may respond to a given stimulus. The relationship between the amplitude of the muscle contraction and the current applied is sigmoid, not linear. At low currents, an insufficient number of axons is depolarized. As the current increases, increasingly more axons are depolarized to threshold, and the strength of the muscle contraction increases up to a maximum level. The mechanism of action of nerve cell activation is via the opening of sodium channels. (See page 501: Physiology and Pharmacology: Structure.) 2. The duration of the current delivered by a nerve stimulator should be approximately: A. 0.2 sec B. 0.02 sec C. 0.2 ms
D. 0.02 ms E. 2.0 ms 2. C. The duration of the current delivered by a nerve stimulator should be 0.1 to 0.2 ms. (See page 501: Physiology and Pharmacology: Nerve Stimulation.) 3. Which of the following statements regarding acetylcholine (Ach) is FALSE? A. The amount of Ach released with repetitive stimulation decreases. B. Calcium is required for vesicle binding to docking proteins and subsequent release of Ach. C. The action of magnesium augments the release of Ach from vesicle stores. D. Ach is released in quanta, each of which contains 5000 to 10,000 molecules. E. In the absence of stimulation, a small amount of Ach is released at random. 3. C. Ach is packaged into 45-nm vesicles, each of which contains 5000 to 10,000 molecules of Ach. A few vesicles are available for immediate release, but a much larger pool can be recruited with time. With repetitive stimulation, the amount of Ach released decreases rapidly because of the limited availability of immediately releasable Ach. Even in the absence of nerve stimulation, Ach is released in small quantities called quanta, producing so-called miniature end plate potentials. When an action potential reaches the nerve terminal, about 200 to 400 quanta are released simultaneously, causing a rapid increase in the concentration of Ach at the motor end plate. Calcium enters the nerve terminals through channels that open in response to depolarization and is responsible for release of Ach from vesicles. Magnesium antagonizes the action of calcium and causes inhibition of Ach release. (See page 501: Physiology and Pharmacology: Release of Acetylcholine.) 4. Which of the following statements regarding neuromuscular blocking drugs (NMBs) is FALSE?
A. The ED50 is the median dose corresponding to a 50% depression in twitch. B. The ED95 corresponds to the dose required to achieve neuromuscular blockade in 95% of patients. C. The ED95 of vecuronium is approximately 0.05 mg/kg. D. The time to maximal neuromuscular blockade can be shortened if the dose of NMB is increased. E. The duration of action of NMBs increases with increasing dose. 4. B. The ED50 and ED95 are two measures of NMB potency. The ED50 is the median dose corresponding to a 50% depression in twitch. The ED95, a more clinically relevant measure of potency, is defined as the amount of drug necessary to produce a 95% block in twitch response in half of patients. For example, the ED95 of vecuronium is approximately 0.05 mg/kg. The time needed to reach maximal neuromuscular blockade and duration of block are both affected by amount of drug given. The response time can be shortened and the duration increased when an increased amount of drug is administered. (See page 503: Neuromuscular Blocking Agents: Pharmacologic Characteristics of Neuromuscular Blocking Agents.) 5. Which of the following statements regarding the depolarizing blockade produced by succinylcholine (Sch) is FALSE? A. During phase I block, fade in response to train-of-four (TOF) stimulus is not observed. B. Phase II block is not antagonized by cholinesterase inhibitors. C. After administration of a 7 to 10 mg/kg dose of Sch, TOF and tetanic fade typically become apparent. D. The prevalence of fasciculations after injection of Sch is greater than 50%. E. Sinus bradycardia in response to Sch is more common in children than in adults. 5. B. Administration of a usual intubating dose of Sch produces a phase I block marked by a decrease in single-twitch height, but sustained
response to high-frequency stimulation and minimal, if any, TOF or tetanic fade. Phase I blockade is potentiated by inhibitors of acetylcholinesterase. After administration of larger doses of Sch (7–10 mg/kg) or within 30 to 60 minutes after initiating infusion, TOF and tetanic fade typically become apparent. This is referred to as phase II blockade. In contrast to phase I block, phase II block can be antagonized by acetylcholinesterase inhibitors. Sch produces a number of characteristic side effects. Fasciculations in response to Sch injection occur in 60% to 90% of patients and can often be reduced with the prior administration of a small dose of a nondepolarizing neuromuscular blocking drug such as rocuronium. Sinus bradycardia with nodal or ventricular escape beats is a relatively common cardiovascular side effect, more so in children than adults. (See page 504: Depolarizing Drugs: Characteristics of Depolarizing Blockade.) 6. Regarding the clinical use of succinylcholine (Sch), all of the following statements are true EXCEPT: A. Infants and children are relatively resistant to Sch compared with adults. B. The duration of neuromuscular blockade produced by Sch is significantly increased in patients homozygous for an atypical form of plasma cholinesterase. C. Increases in serum potassium levels after Sch injection can be mitigated by precurarization. D. Precurarization may be effective at blocking the increase in intragastric pressure observed after Sch administration. E. At a dose of 1 mg/kg, the duration of action of Sch is approximately 5 to 6 minutes. 6. C. Sch is the only depolarizing neuromuscular blocking drug (NMDB) regularly used in clinical practice. It has an onset of action of approximately 30 to 60 seconds and a duration of action of 5 to 6 minutes, making it a useful agent for rapid sequence intubations and for patients in whom prolonged muscle relaxation is not desired. Side effects commonly observed after administration of a neuromuscular blocking drug include muscle fasciculations and an elevation of intragastric and intraocular pressures. Both of these reactions can be
blocked (but not with 100% consistency) by the prior administration of a small dose of nondepolarizing NMB (precurarization). Sch also increases serum potassium levels by approximately 0.5 to 1.0 mEq/L. This effect is not prevented by precurarization. Therefore, Sch should be used with caution in patients at risk of developing clinically significant hyperkalemia. Sch is metabolized by plasma cholinesterase. Patients with atypical versions of this enzyme experience prolongation of neuromuscular blockade caused by succinylcholine. However, this prolongation is only significant in patients who are homozygous for atypical cholinesterase. (See page 504: Depolarizing Drugs: Succinylcholine.) 7. All of the following statements regarding the pharmacokinetics of nondepolarizing neuromuscular blocking drugs (NMBs) are true EXCEPT: A. Termination of the clinical effects of vecuronium depends primarily on redistribution rather than elimination. B. Termination of the clinical effects of cisatracurium depends primarily on elimination. C. The volume of distribution of most nondepolarizing NMBs is approximately equal to extracellular fluid (ECF) volume. D. More potent drugs have a faster onset of action than less potent agents. E. The onset and duration of action are determined by the concentration of drug at its site of action. 7. D. The duration of action of NMBs is a function of either their elimination from the body or redistribution away from the site of effect. Cisatracurium is an intermediate-duration drug whose effects are terminated as a result of elimination. By contrast, vecuronium has a long elimination half-life but an intermediate effect duration as a result of redistribution away from the motor end plate. The volume of distribution of nondepolarizing NMBs is about equal to the volume of the ECF compartment. The onset and duration of action of most NMBs are determined by the time required for drug concentrations to reach a critical level at their site of action. Drug concentration at the effect site approximately parallels plasma concentration, but drug onset lags
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slightly behind peak plasma concentration. More potent drugs actually have slower onsets of action than less potent ones because there are fewer molecules of the more potent agent than of an equivalent dose of a less potent agent. (See page 507: Nondepolarizing Drugs: Pharmacokinetics and page 507: Onset and Duration of Action.) 8. Which of the following muscle groups demonstrates the earliest recovery from neuromuscular blockade after administration of an anticholinesterase agent? A. Adductor pollicis B. Diaphragm C. Geniohyoid D. Pharyngeal E. Flexor hallucis 8. B. The diaphragm exhibits the most rapid recovery from neuromuscular blockade. Recovery of upper airway and pharyngeal muscles (e.g., geniohyoid) and the flexor hallucis muscle generally parallels that of the adductor pollicis. (See page 517: Monitoring Neuromuscular Blockade: Choice of Muscle.) 9. Which of the following is an acetylcholinesterase inhibitor with an onset of action most similar to atropine? A. Glycopyrrolate B. Edrophonium C. Neostigmine D. Pyridostigmine E. Physostigmine 9. B. Anticholinergic agents such as atropine and glycopyrrolate are frequently administered with neuromuscular reversal agents to blunt the cardiovascular effects of vagal stimulation produced by reversal agents. To achieve the best effect, agents with similar pharmacokinetics should be paired. The onset of action of atropine is rapid (∼1 min) and closely parallels that of edrophonium. The onset of action of neostigmine is about 7 to 11 minutes, and pyridostigmine's onset of action is 15 to 20
minutes. Physostigmine has an onset of about 5 minutes. It is not used as a neuromuscular reversal agent because of its central side effects. The pharmacokinetic profile of glycopyrrolate (onset, 2–3 minutes) is most similar to that of neostigmine. (See page 522: Antagonism of Neuromuscular Block: Reversal Agents.) 10. All of the following are side effects associated with anticholinesterase drugs EXCEPT: A. increased salivation B. increased peristalsis C. bradycardia D. bronchodilation E. increased bladder motility 10. D. Anticholinesterase agents produce vagal stimulation, leading to bradycardia and bradyarrhythmias. Other cholinergic effects observed with anticholinesterase drugs include increased salivation and increased bladder and bowel motility. Anticholinesterases may also be associated with bronchoconstriction, not bronchodilation. (See page 522: Antagonism of Neuromuscular Block: Anticholinesterases: Other Effects.) 11. All of the following statements about Sugammadex are true EXCEPT: A. Sugammadex has no affect on succinylcholine. B. Sugammadex has a higher affinity for rocuronium than for vecuronium and pancuronium. C. Sugammadex acts on neuromuscular blocking agents that do not contain a steroid nucleus. D. In larger doses, Sugammadex is an effective agent when neuromuscular blockade is deep. E. Sugammadex has no known major cardiovascular side effects. 11. C. Sugammadex (previously referred to as ORG 25969) reverses neuromuscular blockade by binding to neuromuscular blocking agents in the plasma, which decreases the free or unbound drug in the plasma. This creates a concentration gradient between the neuromuscular
junction and plasma, leading to the movement of the respective agents from the neuromuscular junction to the plasma and thus a decrease in neuromuscular block. Sugammadex selectively binds neuromuscular blocking agents that contain a steroid nucleus (rocuronium, vecuronium, and pancuronium), with a noted higher affinity toward rocuronium compared with vecuronium and pancuronium. There are no known major cardiovascular side effects because it does not bind to any known receptors. In larger doses, Sugammadex can be effective when blockade is deep. (See page 522: Antagonism of Neuromuscular Block: Sugammadex.) For questions 12 through 18, answer A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 12. Which of the following statements about the nondepolarizing neuromuscular blocking drugs (NMDBs) is/are TRUE? 1. Laudanosine is a metabolite of cisatracurium. 2. Pancuronium is associated with histamine release. 3. Mivacurium is metabolized by plasma cholinesterase. 4. Hypotension after administration of d-tubocurarine is mainly the result of autonomic ganglionic blockade. 12. B. Laudanosine is a compound produced by the ester hydrolysis of atracurium and cisatracurium. Similar to succinylcholine, mivacurium is metabolized by plasma cholinesterase. Several of the nondepolarizing NMBs are associated with histamine release, which may cause transient hypotension after administration. This is the primary reason for the hypotension observed after administration of d-tubocurarine; it also causes ganglionic block. Pancuronium does not release histamine but does appear to cause a transient increase in catecholamine release, leading to a temporary increase in heart rate, blood pressure, and cardiac output. (See page 507: Nondepolarizing Drugs: Individual Nondepolarizing Agents.) 13. Which of the following agents augment(s) neuromuscular blockade? 1. Isoflurane
2. Erythromycin 3. Lidocaine 4. Metronidazole 13. B. Several agents potentiate the effect of the neuromuscular blocking drugs. These include the halogenated inhalational agents such as isoflurane and local anesthetics such as lidocaine. Aminoglycosides such as neomycin and streptomycin also potentiate neuromuscular blockade. Erythromycin, penicillins, and metronidazole, however, do not produce this effect. (See page 514: Drug Interactions.) 14. Which of the following statements regarding patients with myasthenia gravis is/are TRUE? 1. They often demonstrate resistance to depolarizing neuromuscular blocking drugs (NMDBs). 2. They often demonstrate resistance to nondepolarizing NMBDs. 3. The number of acetylcholine quanta at the neuromuscular junction is generally normal or increased. 4. They demonstrate a voltage increment in response to repeated stimulation at 2 to 5 Hz. 14. B. Myasthenia gravis is an autoimmune disorder characterized by the production of antibodies to postsynaptic acetylcholine receptors. The number of acetylcholine (Ach) quanta at the neuromuscular junction is normal or increased. However, muscle contraction in response to acetylcholine is blunted by a functional decline in acetylcholine receptors. The characteristic electromyographic finding in patients with myasthenia gravis is a voltage decrement in response to repeated stimulation at the 2- to 5-Hz level. Patients with myasthenia gravis have unpredictable responses to NMBs. They are often resistant to succinylcholine, partly because of the presence of higher concentrations of Ach at the motor end plate. In contrast, sensitivity and prolonged duration of action are usually observed in response to nondepolarizing NMBs, as a result of the decreased number of functional Ach receptors present on postsynaptic membranes. (See page 515: Altered Responses to Neuromuscular Blocking Agents: Myasthenia Gravis.)
15. In which of the following patients is a greater than average increase in serum potassium in response to succinylcholine (Sch) administration found compared with the general population? 1. A 57-year-old woman who sustained extensive burns 1 week ago 2. A 19-year-old patient with T12 paralysis after a motor vehicle collision 1 month ago 3. A 69-year-old man after a major stroke 4. A 40-year-old woman diagnosed with myasthenia gravis 1 month ago 15. A. An exaggerated increase in serum potassium concentration after Sch administration is relatively more common in children with muscular dystrophies (e.g., Duchenne). It is also observed as early as 24 to 48 hours after extensive burn injuries; this response usually lessens with healing. In addition, patients with upper motor neuron lesions are more susceptible to hyperkalemia induced by Sch. This response is most prominent when the drug is given 1 week to 6 months after injury, although it may occur at any time. Hyperkalemia after Sch administration is not frequently associated with myasthenia gravis. (See page 504: Depolarizing Drugs: Side Effects.) 16. Which of the following statements regarding train-of-four (TOF) response monitoring of the degree of nondepolarizing neuromuscular blockade is/are TRUE? 1. The second twitch reappears when approximately 80% to 90% of receptors remained blocked. 2. The third twitch reappears when approximately 70% to 80% of receptors remained blocked. 3. All four twitches are visible when 65% to 75% of receptors are blocked. 4. The single-twitch height has recovered to about 100% when the TOF ratio is approximately 70%. 16. E. TOF response monitoring to nondepolarizing neuromuscular blockade involves the application of four stimuli at 0.5-second intervals
(2 Hz). Recovery from neuromuscular block is measured by the return of response to these stimuli. In general, the first twitch reappears if less than 90% to 92% of receptors are blocked (8% to 10% are unblocked). The second twitch appears when 80% to 90% of receptors remain blocked, and the third appears when 75% to 80% are blocked. All four responses are usually visible when there is less than 65% to 75% receptor blockade. At this time, single-twitch height has recovered to approximately 100% of pre-relaxant height, and the height of T4 increases to approximately 70% of the height of T1. (See page 517: Monitoring Neuromuscular Block: Monitoring Modalities.) P 17. Regarding the differential impact of neuromuscular blocking drugs (NMDBs) on specific muscle groups, which of the following statements is/are TRUE? 1. The adductor pollicis is relatively resistant to nondepolarizing NMBs compared with the diaphragm. 2. Facial nerve stimulation with monitoring of response in the eyebrow is reliably predictive of intubating conditions. 3. Time to maximal response occurs more quickly in the adductor pollicis than in the diaphragm. 4. The diaphragm and laryngeal muscles are relatively resistant to nondepolarizing agents. 17. C. Muscle groups demonstrate a differential response to NMBs. The adductor pollicis is relatively sensitive to nondepolarizing NMBs, but the diaphragm and laryngeal muscles are relatively resistant. The time to maximal blockade occurs somewhat later in the adductor pollicis compared with the more centrally located airway muscles. Facial nerve stimulation with response monitored in the eyebrow is thought to be indicative of the action of the corrugator supercilii muscle. The impact of nondepolarizing NMBs on this muscle approximates that of the laryngeal adductors, so response monitoring to eyebrow movement may be a reliable predictor of adequate intubating conditions. However, monitoring in the supraorbital region may pose some technical difficulties. (See page 517: Monitoring Neuromuscular Block: Choice of Muscle.)
18. Which of the following acetylcholinesterase inhibitors can cross the blood–brain barrier? 1. Edrophonium 2. Pyridostigmine 3. Neostigmine 4. Physostigmine 18. D. Neostigmine, edrophonium, and pyridostigmine are all charged quaternary ammonium compounds that do not cross the blood–brain barrier. Physostigmine is an uncharged molecule that can cross the blood–brain barrier. (See page 522: Antagonism of Neuromuscular Block: Reversal Agents.)
Chapter 21 Local Anesthetics 1. Which statement regarding myelinated nerves is FALSE? A. They have a diameter of more than 1 μm. B. They are surrounded by Schwann cells, which account for more than half of the nerve's thickness. C. They conduct impulses more slowly than similar-sized unmyelinated nerves. D. They have both afferent and efferent functions. E. The nodes of Ranvier are covered by negatively charged glycoproteins. 1. C. Myelinated nerves generally conduct impulses faster than unmyelinated nerves. The presence of myelin accelerates conduction velocity by increased electrical isolation of nerve fibers and by saltatory conduction. Increased nerve diameter accelerates conduction velocity both by increased myelination and by improved electrical cable conduction properties of the nerve. Myelinated and unmyelinated nerves carry both afferent and efferent functions. All nerves with a diameter larger than 1 μm are myelinated. Myelinated nerve fibers in the peripheral nervous system are segmentally enclosed by Schwann cells forming a bilipid membrane that is wrapped several hundred times around each axon. Myelinated nerve fibers in the central nervous system are segmentally enclosed by oligodendrocytes. Thus, myelin accounts for more than half the thickness of large nerve fibers. The nodes of Ranvier are separated by the myelinated regions. The nodes are covered by interdigitations from nonmyelinated Schwann cells and by negatively charged glycoproteins. (See page 531: Anatomy of Nerves.) 2. Which statement regarding neuronal conduction is FALSE? A. The resting membrane potential is predominantly maintained by a potassium gradient with a 10 times greater concentration of potassium within the cell.
B. Generation of action potentials is primarily the result of activation of voltage-gated sodium channels. C. Impulse generation is an all-or-nothing phenomenon. D. A three-state kinetic scheme conceptualizes the change in sodium channel conformation and accounts for changes in sodium conductance during depolarization and repolarization. E. The resting membrane potential of neural membranes averages -30 to -40 mV. 2. E. The resting potential of neural membranes averages –60 to –70 mV, with the interior being negative compared with the exterior. This resting potential is predominately maintained by a potassium gradient with a 10 times greater concentration of potassium within the cell. An active protein pump transports potassium into the cell and sodium out of the cell through voltage-gated potassium channels. Generation of an action potential is primarily the result of voltage-gated sodium channels. After activation (opening) of the sodium channel, it spontaneously closes into an inactive state and then reverts to a resting confirmation. Thus, a three-state kinetic scheme conceptualizes the changes in the sodium channel confirmation that account for shifts in sodium conductance during depolarization and repolarization. An action potential is generated when the depolarization threshold of an axon is reached. This threshold is not an absolute voltage but depends on the dynamics of the sodium and potassium channels. After an action potential is generated, propagation of the potential along nerve fibers is required for information to be transmitted. Both impulse generation and propagation are “all-or-nothing” phenomena. Nonmyelinated fibers require achievement of threshold potential at the immediately adjacent membrane, but myelinated fibers require generation of threshold potential at a subsequent node of Ranvier. (See page 532: Electrophysiology of Neural Conduction and Voltage-Gated Sodium Channels.) 3. The rate of absorption from injection of local anesthetic to various sites generally increases in the following order: A. intercostal, caudal, epidural, brachial plexus, sciatic/femoral B. caudal, intercostal, epidural, brachial plexus, sciatic/femoral
C. intercostal, epidural, caudal, brachial plexus, sciatic/femoral D. sciatic/femoral, brachial plexus, epidural, caudal, intercostal E. intercostal, brachial plexus, epidural, caudal, sciatic/femoral 3. D. In general, local anesthetics with decreased systemic absorption have a greater margin of safety in clinical use. The rate and extent of absorption depend on numerous factors; the most important factors are the site of injection, the dose of local anesthetic, the physicochemical properties of the local anesthetic, and the addition of epinephrine. The relative amount of fat and vasculature surrounding the site of injection interact with the physicochemical properties of the local anesthetic and affect the rate of systemic uptake. In general, areas with greater vascularity have more rapid and complete uptake than those with more fat, regardless of the type of local anesthetic. Hence, multiple injections near intercostal vascular bundles have a faster uptake than injections in the buttocks and groin. The greater the total dose of local anesthetic injected, the greater the systemic absorption and peak blood levels. (See page 536: Chemical Properties and Relationship to Activity and Potency.) 4. Which of the following descriptions of local anesthetics is FALSE? A. They are weak bases. B. The charged form of local anesthetics is lipid soluble. C. They have substituted benzene rings. D. They contain either an ester or amide linkage. E. They exert their effects on the intracellular side of the sodium channel. 4. B. The clinically used local anesthetics consist of a lipid-soluble substituted benzene ring linked to an amine group (tertiary or quaternary, depending on the pKa and pH) via an alkyl chain containing either an amide or ester linkage. The type of linkage separates the local anesthetics into either amino amides, which are metabolized in the liver, or aminoesters, which are metabolized by plasma cholinesterases. Several chemical properties of local anesthetics affect their efficacy and potency. All clinically used local anesthetics are weak bases that can exist as either the lipid-soluble (neutral) form or as the hydrophilic
(charged) form. The primary site of action of local anesthetics appears to exist on the intracellular side of the sodium channel, and the charged form appears to be the predominately active form. Penetration of the lipid-soluble (neutral) form through the lipid neural membrane appears to be the primary form of access of local anesthetic molecules. Increased lipid solubility usually hastens the rate of onset of action, increases the duration of action, and increases potency. The degree of protein binding also affects activity of local anesthetics because only the unbound form is free for pharmacologic activity. In general, increased protein binding is associated with an increased duration of action. (See page 536: Chemical Properties and Relationship to Activity and Potency.) 5. Which statement concerning pKa is FALSE? A. The pKa is the dissociation constant. B. When the pH equals the pKa of a compound, 50% of it is neutral and 50% of it is charged. C. Increasing the pKa of a local anesthetic increases the lipidsoluble form. D. Onset of action is slowed by increasing the pKa. E. Knowing the pKa of a local anesthetic allows one to predict the relative speed of its onset of action. 5. C. The combination of pH of the environment and pKa, or dissociation constant, of a local anesthetic determines how much of the compound exists in each form. Decreasing the pKa for a given environmental pH increases the percentage of the lipid-soluble form and hastens penetration of neural membranes and hence the onset of action. (See page 536: Chemical Properties and Relationship to Activity and Potency.) 6. Which statement regarding the cardiovascular toxicity of bupivacaine is FALSE? A. Vasodilation is a prominent feature. B. Bupivacaine quickly dissociates from cardiac sodium channels during cardiac diastole. C. Cardiac myocyte release and utilization of calcium are inhibited.
D. Mitochondrial energy metabolism is reduced. E. The cardiotoxicity of bupivacaine may be mediated centrally and peripherally. 6. B. It has been demonstrated that the central and peripheral nervous systems are involved with the cardiotoxic effects of bupivacaine, which may be exacerbated by its potent direct vasodilating properties. Bupivacaine exhibits a much stronger binding affinity to resting and inactivated sodium channels than lidocaine. It dissociates from sodium channels during cardiac diastole much more slowly than lidocaine, so slowly that complete sodium channel recovery is not achieved and a bupivacaine conduction block accumulates. Bupivacaine also inhibits myocyte release and utilization of calcium and reduces mitochondrial energy metabolism, especially during hypoxia. (See page 542: Toxicity of Local Anesthetics.) 7. Which statement concerning clearance and elimination of local anesthetics is FALSE? A. Ester local anesthetics are primarily cleared by plasma cholinesterases. B. Local anesthetics with higher rates of clearance have greater margins of safety. C. Renal disease is important in altering the pharmacokinetic parameters of local anesthetics. D. Protein binding of amino amide local anesthetics is important in determining the rate of clearance. E. Correlation of resultant systemic blood levels between the dose of local anesthetic and the patient's weight is often inconsistent. 7. C. Whereas clearance of ester local anesthetics is primarily dependent on plasma clearance by cholinesterase, amide local anesthetic clearance is dependent on hepatic metabolism. Thus, hepatic extraction, hepatic perfusion, hepatic metabolism, and protein binding primarily determine the rate of clearance of amide local anesthetics. In general, local anesthetics with higher rates of clearance have greater margins of safety. Renal disease has little effect on the pharmacokinetic
parameters of local anesthetics. Correlation of the resulting systemic blood levels between the dose of local anesthetic and the patient's weight often is inconsistent. (See page 538: Pharmacokinetics of Local Anesthetics.) 8. Which statement concerning treatment of systemic toxicity from local anesthetics is FALSE? A. Signs of central nervous system (CNS) toxicity typically occur before cardiovascular events. B. Propofol can terminate seizures from systemic local anesthetic toxicity. C. Succinylcholine (Sch) may terminate seizure activity. D. Ventricular dysrhythmias may be difficult to treat. E. Amiodarone is indicated in the treatment of bupivacaine toxicity. 8. C. Treatment of patients with systemic toxicity is primarily supportive. Injection of the local anesthetic should be stopped. Oxygenation and ventilation should be maintained because systemic toxicity of local anesthetics is enhanced by hypoxemia, hypercarbia, and acidosis. If needed, the patient's trachea should be intubated and positive-pressure ventilation instituted. Signs of CNS toxicity occur before cardiovascular events. Seizures may increase body metabolism and cause hypoxemia, hypercarbia, and acidosis (three well-known factors that further enhance the systemic toxicity of local anesthetics). Intravenous administration of thiopental, midazolam, and propofol may terminate seizures from systemic local anesthetic toxicity. Sch may terminate muscular activity from seizures and facilitate ventilation and oxygenation; however, Sch does not terminate seizure activity in the CNS, and increased cerebral metabolic demands continue unabated. Potent local anesthetics (e.g., bupivacaine) may produce profound cardiovascular depression and malignant dysrhythmias that should be treated promptly. Oxygenation and ventilation must be immediately instituted, with cardiopulmonary resuscitation used if needed. Ventricular dysrhythmias may be difficult to treat and may need repeated electrical cardioversion and large doses of epinephrine,
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vasopressin, and amiodarone. (See page 544: Treatment of Systemic Toxicity from Local Anesthetics.) 9. Which statement concerning transient neurologic symptoms (TNS) after spinal anesthesia is FALSE? A. An increased risk of TNS is associated with lidocaine. B. The baricity of the local anesthetic is an important factor in the development of TNS. C. The dose of local anesthetic is not an important factor in the development of TNS. D. TNS may be a manifestation of subclinical neurotoxicity. E. The incidence of TNS varies with patient position. 9. B. There is a 4% to 40% incidence of TNS after lidocaine spinal anesthesia. All local anesthetics have the potential to be neurotoxic, particularly in higher concentrations, and symptoms have been reported with multiple agents. The incidence of TNS varies with the type of surgical procedure and positioning (particularly the lithotomy position). Apparently, the incidence is unaffected by the baricity or dose. Reports of cauda equina syndrome after spinal anesthesia have led several authors to label TNS as a manifestation of subclinical neural toxicity. Other potential causes of TNS include patient positioning, early mobilization, needle trauma, neural ischemia, pooling of local anesthetics, and the addition of glucose. Clearly, the cause of TNS remains undetermined, and further studies are needed to elucidate the underlying mechanism. (See page 545: Transient Neurologic Symptoms After Spinal Anesthesia.) 10. Which of the following statements is FALSE? A. Bupivacaine 0.75% is not an acceptable concentration for obstetric use. B. Central nervous system (CNS) toxicity is more common with epidural local anesthetic injection than with peripheral nerve blocks. C. Levobupivacaine is approximately equipotent to racemic bupivacaine.
D. Both ropivacaine and levobupivacaine appear to have approximately 30% to 40% less systemic toxicity than bupivacaine on a milligram-to-milligram basis. E. Levobupivacaine is an isomer of bupivacaine. 10. B. Enhanced awareness of potential cardiovascular toxicity with long-acting local anesthetics led to withdrawal of Food and Drug Administration approval for high concentrations of bupivacaine (0.75%) for obstetric use in the United States. The incidence of CNS toxicity with epidural injection is approximately one in 10,000; with peripheral nerve blocks, it is seven in 10,000. Levobupivacaine, an isomer of bupivacaine, appears to be approximately equally potent to racemic bupivacaine for epidural anesthesia. Both ropivacaine and levobupivacaine appear to have approximately 30% to 40% less toxicity than bupivacaine on a milligram-to-milligram basis in both animal and human volunteer studies. This is likely the result of reduced affinity in brain and myocardial tissue. (See page 542: Systemic Toxicity of Local Anesthetics: Central Nervous System Toxicity.) 11. All of the following local anesthetics are racemic mixtures EXCEPT: A. lidocaine B. bupivacaine C. mepivacaine D. tetracaine E. chloroprocaine 11. A. All currently available local anesthetics, with the exception of lidocaine (achiral), ropivacaine, and levo-bupivacaine, are racemic mixtures. Stereoisomers of local anesthetics appear to have potentially different effects on anesthetic potency, pharmacokinetics, and systemic toxicity. For example, R isomers appear to have greater in vitro potency for block of both neural and cardiac sodium channels and may thus have greater therapeutic efficacy and potential systemic toxicity. (See page 536: Pharmacology and Pharmacodynamics.) For questions 12 to 19, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are
correct. 12. Which of the following statements concerning spinal administration of opioids are TRUE? 1. It is not dependent on supraspinal mechanisms. 2. Combining a local anesthetic with opioids results in synergistic analgesia. 3. 2-Chloroprocaine appears to decrease the effectiveness of epidural opioids. 4. Spinal administration of opioids provides analgesia primarily by attenuating the α δ fiber nociception. 12. A. Opioids have multiple central neuraxial mechanisms of analgesic action. Supraspinal administration of opioids results in analgesia via opiate receptors in multiple sites, including activation of descending spinal pathways. Spinal administration of opioids provides analgesia primarily by attenuating C-fiber nociception and is independent of supraspinal mechanisms. Coadministration of opioids with most local anesthetics results in synergistic analgesia. An exception to this analgesic synergy is 2-chloroprocaine, which appears to decrease the effectiveness of epidural opioids when used for epidural anesthesia. The mechanism for this action is unclear but does not appear to involve direct anatomization of opioid receptors. (See page 538: Opioids.) 13. Which of the following statements concerning peripheral opioid receptors are TRUE? 1. Peripheral opioid receptors are found primarily at the end terminals of efferent fibers. 2. Intra-articular and peri-incisional opioids have not been found to provide postoperative analgesia. 3. Local tissue inflammation does not influence the analgesic effectiveness of peripheral opioid agonists. 4. Combining local anesthetics with opioids for peripheral nerve blocks appears to be ineffective. 13. C. The recent discovery of peripheral opioid receptors offers yet another circumstance in which the coadministration of local anesthetics
and opioids may be useful. Cumulative evidence now suggests that neither intra-articular administration of local anesthetic and opioid for postoperative analgesia nor combining local anesthetics and opioids for nerve blocks increases efficacy. There are several reasons for a predicted lack of effective coadministration of local anesthetics and opioids for peripheral nerve blocks. (See page 538: Opioids.) 14. Which of the following statements concerning local anesthetics are TRUE? 1. pKa determines the onset of action. 2. Lipophilicity influences potency. 3. Protein binding influences the duration of action. 4. Clinically used local anesthetics cannot be alkalinized beyond a pH of 9 before precipitation occurs. 14. E. The physicochemical properties of local anesthetics affect systemic absorption. In general, use of the more potent agents with greater lipid solubility and protein binding results in lower systemic absorption and lower peak blood levels. Sequestration into lipid-rich compartments and locally induced vasoconstriction are two mechanisms that affect systemic absorption. The pH of commercial preparations of local anesthetics ranges from 3.9 to 6.47 and is especially acidic if they are prepackaged with epinephrine. Because the pKa of commonly used local anesthetics ranges from 7.6 to 8.9, less than 3% of the commercially prepared local anesthetic exists as the lipid-soluble neutral form. However, clinically used local anesthetics cannot be alkalinized beyond a pH of 6.05 to 8 before precipitation occurs, and such a pH will increase the neutral form only to about 10%. (See page 538: Pharmacokinetics of Local Anesthetics and page 537: Alkalinization of Local Anesthetic Solution.) 15. Systemic absorption and peak blood levels of local anesthetics are: 1. linearly related to the total dose of local anesthetic injected 2. reduced with the addition of epinephrine, especially for the less lipid-soluble, less potent, shorter-acting agents
3. diminished with the more potent agents with greater lipid solubility and protein binding 4. independent of anesthetic concentration 15. E. Epinephrine may counteract the inherent vasodilating characteristics of most local anesthetics. The reduction in blood concentration with epinephrine is most effective for the less lipidsoluble, less potent, shorter-acting agents. The greater the total dose of local anesthetic injected, the greater the systemic absorption and peak blood levels will be. This relationship is nearly linear and is relatively unaffected by the anesthetic concentration and speed of injection. (See page 537: Systemic Absorption and Additives to Increase Local Anesthetic Activity: Epinephrine.) 16. Which of the following statements concerning the central nervous system (CNS) toxicity of local anesthetics are FALSE? 1. CNS depression is a sign of high-dose local anesthetic toxicity. 2. CNS excitation is a sign of low-dose local anesthetic toxicity. 3. In general, decreased local anesthetic protein binding decreases potential CNS toxicity. 4. The seizure threshold is increased by the administration of benzodiazepines. 16. A. Decreases in local anesthetic protein binding and clearance increase potential CNS toxicity. Local anesthetics readily cross the blood–brain barrier, and generalized CNS toxicity may occur from systemic absorption or direct vascular injection. Signs of generalized CNS toxicity from local anesthetics are dose dependent. Low doses produce CNS depression, and higher doses result in CNS excitation and seizures. The rate of intravenous administration of local anesthetic affects signs of CNS toxicity because higher rates of infusion lessen the appearance of CNS depression while leaving excitation intact. This dichotomous reaction to local anesthetics may be caused by a greater sensitivity of cortical inhibitory neurons to the impulse-blocking effects of local anesthetics. External factors, such as acidosis and increased PCO2, may increase CNS toxicity, perhaps by increasing cerebral perfusion and decreasing protein binding of the local anesthetic. Seizure thresholds in response to local anesthetics are increased by
administration of barbiturates and benzodiazepines. (See page 542: Toxicity of Local Anesthetics: Central Nervous System Toxicity.) 17. Which of the following statements regarding the cardiovascular toxicity of local anesthetics are TRUE? 1. In general, much greater doses of local anesthetics are required to produce cardiovascular toxicity than neurotoxicity. P 2. Bupivacaine cardiovascular toxicity is resistant to resuscitation. 3. The central and peripheral nervous systems may be involved in the increased cardiotoxicity seen with bupivacaine. 4. Generally, the more potent, more water-soluble agents have increased cardiotoxicity. 17. A. In general, much greater doses of local anesthetics are required to produce cardiovascular toxicity than central nervous system toxicity. Similar to CNS toxicity, the potency for cardiovascular toxicity reflects the anesthetic potency of the agent. Recent attention has focused on the apparently exceptional cardiotoxicity of the more potent, more lipid-soluble agents (bupivacaine, etidocaine). These agents appear to have a different sequence of cardiovascular toxicity than the less potent agents. For example, whereas increasing doses of lidocaine lead to hypotension, bradycardia, and hypoxia, bupivacaine often results in sudden cardiovascular collapse from ventricular dysrhythmias that are resistant to resuscitation. (See page 542: Toxicity of Local Anesthetics: Cardiovascular Toxicity of Local Anesthetics.) 18. Which of the following statements concerning allergic reactions to local anesthetics are TRUE? 1. True allergic reactions to local anesthetics are rare. 2. Allergic reactions to local anesthetics usually involve a type I reaction. 3. The allergenic potential from esters may result from hydrolytic metabolism to para-aminobenzoic acid. 4. Reactions are more common with amide than with ester anesthetics.
18. A. True allergic reactions to local anesthetics are rare and usually involve type I (immunoglobulin E) or type IV (cellular immunity) reactions. Type I reactions are worrisome because anaphylaxis may occur. They are more common with ester than with amide local anesthetics. True allergy to amide agents is extremely rare. Increased allergenic potential with esters may result from hydrolytic metabolism to para-aminobenzoic acid (a documented allergen). Added preservatives, such as methylparaben and metabisulfite, may also provoke an allergic response. (See page 546: Allergic Reactions to Local Anesthetics.) 19. Intravenous (IV) lidocaine has been associated with which of the following during airway instrumentation? 1. Decreased intraocular pressure 2. Increased intracranial pressure 3. Decreased intraabdominal pressure 4. Fully intact airway reflexes 19. C. IV lidocaine may be effective for decreasing airway sensitivity to instrumentation by depressing airway reflexes and decreasing calcium flux in airway smooth muscle. It is also effective for attenuating increase in intraocular pressure, intracranial pressure, and intraabdominal pressure during airway instrumentation. IV lidocaine also has well-recognized antidysrhythmic effects and is an effective analgesic used to treat patients with postoperative and chronic neuropathic pain. (See page 540: Clinical Use of Local Anesthetics.)
Chapter 22 Drug Interactions 1. Pronounced drug interactions are not commonly seen by anesthesiologists because of all of the following EXCEPT: A. Interactions may occur, but they usually do not present a problem. B. Variability in response to anesthetic drugs is commonly seen. C. The qualitative nature of most anesthetic interactions is predictable even though the magnitude of the responses may not be known with certainty. D. Many intravenous anesthetic drugs have small safety margins, particularly when respiration is supported. E. It is likely that many instances of anesthetic drug interactions go unrecognized. 1. D. Drug interactions are not commonly seen in operating rooms even though patients routinely take antihypertensives, antidepressants, or gastrointestinal drugs in the preoperative period, and most of them receive five to 10 drugs during general anesthesia. One does not normally hear about significant complications attributable to drug interaction, and numerous explanations for this are possible. First, interactions may occur, but they usually do not present a problem. Anesthesia practitioners are always prepared to titrate drugs and deal with the possibility of significant respiratory, central nervous system, and cardiovascular depression. Toxicity from a drug interaction is likely to become a source of morbidity primarily when it occurs in a setting where it is not rapidly recognized and treated. An example of this occurred when opioid–midazolam combination agents were first used by non-anesthesia personnel for endoscopic and radiologic procedures. The unexpectedly large sedative and ventilatory effects led to numerous deaths. A second explanation is variability in response to anesthetic drugs. As a rule, different patients may have a three- to fivefold difference in the therapeutic and toxic effects of a given dose even
when a drug is given alone. Third, the qualitative nature of most anesthetic interactions is predictable, although the magnitude of the response may not be known with certainty. For example, two cardiovascular depressants will almost always produce more hypotension. Similarly, combinations of central nervous system depressants produce more (not less) depression. Drug interactions that produce a totally unexpected or dangerous effect stand out because of their rarity. Fourth, many intravenous anesthetic drugs have large safety margins, particularly when respiration is supported, so small changes in drug concentration are not extremely important. The mere fact that a measurable interaction exists does not mean that it will cause a difference in outcome or the need for intervention. It is noteworthy that clinically meaningful interactions most often involve drugs such as warfarin, digoxin, and theophylline (drugs with only small differences between therapeutic and toxic concentrations). Finally, it is likely that many instances of anesthetic drug interactions go unrecognized (the clinician must consider the possibility to make the diagnosis). Excessive drug effects are often attributed to some ill-defined “patient sensitivity.” When a drug fails to produce an effect, it is because a patient is “tolerant” or “resistant.” It is almost never considered a drug reaction or interaction. (See page 550: Problems Created by Drug–Drug Interaction.) 2. Pharmacokinetic interaction is defined as one drug altering what property of another drug? A. Absorption B. Distribution C. Metabolism D. Elimination E. All of the above 2. E. A pharmacokinetic interaction occurs when one drug alters the absorption, distribution, metabolism, or elimination of another. A pharmacodynamic interaction occurs when one drug alters the sensitivity of a target receptor to the effects of a second drug. This means that the dose–response or concentration–response curve is shifted by another medication. An example of a drug-delayed absorption by a
change in the physiologic environment is morphine's decreasing gastrointestinal motility so that absorption of orally administered acetaminophen is slowed. Another example of a drug's influencing the absorption of another is the common addition of epinephrine to a local anesthetic solution to retard uptake of the local anesthetic from the site of action. This effect also influences the distribution of the local anesthetic. Distribution of a drug may also be influenced by coadministering a second drug that changes the pH of the environment. Also, administering two drugs that compete for protein-binding sites results in an increase of the free (active) fraction of each drug. Metabolism of one drug can be either increased or decreased by the presence of another; an example is neostigmine's inhibiting both motor end plate acetylcholinesterase and plasma pseudocholinesterase, which may prolong the effect of succinylcholine (and potentially ester-type local anesthetics in the bloodstream). (See page 551: Pharmacokinetic Interactions and Pharmacodynamic Interactions.) 3. Monoamine oxidase (MAO) inhibitors: A. may increase the effect of indirect-acting sympathomimetics B. may interact with morphine to increase the brain concentration of serotonin C. may interfere with beta-blockers D. may be safely given with meperidine E. should be discontinued for 24 hours before elective surgery to return enzyme levels to baseline levels 3. A. MAO is found in tissues throughout the body, but the largest amounts are found in the liver, kidney, and brain. MAO acts to regulate the presynaptic pool of norepinephrine, dopamine, epinephrine, and serotonin available for synaptic transmission. MAO exists in two isoforms: MAO-A preferentially metabolizes serotonin, dopamine, and norepinephrine, and MAO-B preferentially metabolizes phenylethylamine and tyramine. MAO inhibitors are used mainly for the treatment of patients with refractory depression and certain other mood disorders. Interaction with indirect-acting sympathomimetic drugs (ephedrine, amphetamine, metaraminol) occurs because MAO inhibitor treatment increases the amount of presynaptic transmitters that can be released
by these drugs. Normal doses of ephedrine may produce exaggerated sympathetic responses, including a severe hypertensive crisis. Deaths have been attributed to severe hyperpyrexia and cerebral hemorrhage. The “wine and cheese reaction” is essentially the same interaction. Many foods, such as aged cheese, contain tyramine, a phenylethyl-amine that has ephedrine-like actions at sympathetic nerve endings. Normal exogenous tyramine is degraded by MAO in the gut wall and liver, but patients taking MAO inhibitors may achieve high systemic concentrations and consequently have a hypertensive crisis. Because MAO plays little role in the metabolism of compounds in the synaptic cleft, the response to sympathomimetics, which act directly on postsynaptic receptor sites (phenylephrine, norepinephrine, epinephrine), should be less affected by such interactions. Beta-blockers can be safely used in these patients. Unquestionably, the most important interaction of MAO inhibitors is with meperidine. When meperidine is given to a patient who is taking an MAO inhibitor, a life-threatening reaction may occur accompanied by excitation, hyperpyrexia, hypertension, profuse sweating, and rigidity. This may progress to seizures, coma, and death. This reaction does not occur in every instance. The mechanism of the interaction between meperidine and MAO inhibitors is unknown, but animal modes suggest that it involves elevation in the brain concentration of serotonin. Current clinical opinion probably favors continuing MAO inhibitor therapy up to the time of therapy. Most patients are receiving these drugs for moderate to severe psychiatric disorders that have not responded to other treatments. It is unpleasant and possibly risky for a patient with refractory depression to endure 2 to 3 weeks without effective therapy. But if a general anesthetic is planned, it seems prudent to use as few drugs as possible. Avoiding drugs with substantial sympathetic effects probably makes sense. Because opioids, such as fentanyl, appear safe and there are no major interactions with local anesthetics or nonsteroidal anti-inflammatory analgesics, providing anesthesia without meperidine should not be a hardship. (See page 553: Monoamine Oxidase Interactions.) 4. Which statement concerning hepatic biotransformation is FALSE? A. Drugs undergo oxidative metabolism by cytochrome P450. B. Cytochrome P450 has low substrate specificity.
C. Removal of drug from blood by hepatic clearance is a function of hepatic blood flow and intrinsic clearance. D. With drugs that have low extraction ratios, hepatic blood flow is the major rate-limiting factor in overall hepatic clearance. E. With drugs that have low extraction ratios, hepatic enzyme activity is a rate-limiting factor. 4. D. Many anesthetic drugs undergo oxidative metabolism by one of the isoforms of the cytochrome P450 found in liver microsomes. The P450 isoforms have low substrate specificity, meaning that drugs of diverse structures can be biotransformed by a single group of enzymes. The removal of drug from the blood by hepatic biotransformation (hepatic clearance) is a function of two independent variables, the hepatic blood flow and the intrinsic clearance (the maximal ability of the liver to metabolize that drug). The intrinsic clearance is often expressed as the extraction ratio, which is defined as the fraction of drug that can be metabolized in a single pass through the liver. Drugs may be classed broadly as high extraction or low extraction, a distinction with important implications for drug interactions. For drugs with high extraction ratios (e.g., lidocaine, propranolol), hepatic blood flow is a rate-limiting factor in overall hepatic clearance (i.e., the delivery of drug to the liver determines the amount cleared). Clearance is decreased by drugs or maneuvers that lower hepatic blood flow. Clearance of these rapidly metabolized drugs is much less sensitive to changes in enzyme activity. Plasma-protein binding does not have a large effect, either. Low-extraction drugs (e.g., diazepam, mepivacaine) behave quite differently because hepatic enzyme activity is rate limiting (hepatic clearance is limited by intrinsic clearance). Stimulation or inhibition of enzyme activity can have a large effect on overall pharmacokinetics. Protein binding is also more likely to affect clearance because the bound forms of these drugs are protected from hepatic metabolism. (See page 554: Hepatic Biotransformation.) 5. Which statement about drug interactions is FALSE? A. A pharmacodynamic interaction occurs when one drug alters the sensitivity of a target receptor or tissue to the effects of a second drug.
B. Additive interactions are most likely to occur when drugs with identical mechanisms are combined. C. There is usually an additive effect between succinylcholine and the nondepolarizing relaxants. D. Synergistic interactions are characterized by small doses of two or more drugs that produce very large effects. E. Isobolographic analysis is used for quantitatively assessing the effects of drug combinations to see whether synergism occurs. 5. C. A pharmacodynamic interaction occurs when one drug alters the sensitivity of a target receptor or tissue to the effects of a second drug. This means that the dose–response or concentration–response curve for one drug is shifted by another. Additive interactions are most likely to occur when drugs with identical mechanisms are combined. There is an antagonistic interaction between succinylcholine and the nondepolarizing relaxants. Antagonistic drug interactions involve deliberate reversal with drugs that compete at the same receptor site. Synergistic drug interactions, in which small doses of two or more drugs can produce very large effects, are most likely to occur when drugs of different classes, or even those with slightly different mechanisms, are used to produce the same effects. Two of the most common techniques used by experimental pharmacologists to study the effects of drug combinations are algebraic (fractional) analysis and isobolographic analysis. (See page 556: Pharmacodynamic Interactions.) For questions 6 to 8, choose A if 1, 2, and 3 are correct, B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 6. Which of the following statements are examples of a pharmaceutical reaction? 1. Bicarbonate added to bupivacaine causes a precipitation reaction. 2. Halogenated anesthetics have been shown to interact with dry soda lyme or baralyme to produce carbon monoxide. 3. Nitric oxide reacts with oxygen to form nitrogen dioxide. 4. Orally administered tetracycline can be inactivated by chelation when it is given with antacids containing magnesium,
calcium, or aluminum. 6. A. A pharmaceutical interaction is a chemical or physical interaction that occurs before a drug is administered or absorbed systemically. The most obvious pharmaceutical drug interactions are the incompatibilities that may occur between intravenous drugs and solution (e.g., precipitation of barbiturate when thiopental is injected together with succinylcholine into an intravenous line). In addition, two drugs may interact chemically to form a toxic compound (e.g., when halogenated anesthetics produce carbon monoxide when interacting with dry soda lyme or nitric oxide forming nitrogen dioxide when it contacts oxygen). Tetracycline inactivation by antacids is an example of a pharmacokinetic reaction. (See page 551: Pharmacokinetic Interactions.) 7. Distribution changes resulting from drug–drug interactions may occur secondary to: 1. alterations in hemodynamics 2. changes in drug ionization 3. changes in binding to plasma and tissue proteins 4. changes in drug metabolism 7. A. Many drug–drug interactions occur when one drug alters the distribution of a second drug. This may result from alterations in hemodynamics, drug ionization, or binding to plasma or tissue proteins. Drug-induced hemodynamic compromise may affect pharmacokinetics. Drugs such as beta-blockers, calcium channel blockers, and vasodilators may decrease cardiac output by a variety of mechanisms and may produce significant changes in drug distribution. For a given rate of drug administration, a decrease of cardiac output will increase the arterial drug concentration to highly perfused tissues such as the brain and myocardium. Drug-induced changes in pH in a particular body region or fluid compartment may alter the distribution of other drugs by so-called “ion trapping.” A drug that is protein bound will not be filtered by a normal glomerulus and (for some drugs) will not be acted upon by drugmetabolizing enzymes. A drug that is highly bound to plasma protein effectively exists as a depot, similar to a deep intramuscular injection. The potential therefore exists that one drug can alter the disposition, clearance, or biologic effect of another by altering its binding. An
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example of this is illustrated by a highly bound potentially toxic drug such as warfarin, which is more than 98% bound to albumin. When another drug is given (e.g., phenylbutazone) that competes for the same binding sites, it displaces warfarin and increases the free fraction, increasing the anticoagulant effect. (See page 551: Pharmacokinetic Interactions.) 8. Which of the following are TRUE? 1. Enzyme induction is an explanation for increased intrinsic clearance. 2. A single inducer can affect the products of several gene families. 3. Phenobarbital may increase the amount of P450 enzyme and may therefore increase the clearance of many drugs. 4. Cimetidine forms an inactive complex with cytochrome P450 and therefore inhibits the metabolism of many drugs, including warfarin and diazepam. 8. E. The most common reason for increased intrinsic clearance is enzyme induction. Many drugs of importance in anesthesiology are metabolized by the cytochrome P450 enzymes. Hundreds of drugs and environmental toxins can stimulate (or induce) microsomal enzymes. Typically, a single inducer can affect the products of several gene families. Phenobarbital increases the amount of many P450 enzymes. The increase in the quantity of enzyme protein can therefore simultaneously increase the clearance of many drugs. Cimetidine has an imidazole group that binds to the heme iron of cytochrome P450 and forms an inactive complex. Cimetidine inhibits the metabolism of many drugs, including warfarin, diazepam, phenytoin, and morphine. (See page 554: Hepatic Biotransformation.)
Chapter 23 Preoperative Patient Assessment and Management 1. All of the following are important predictors of cardiac postoperative complications EXCEPT: A. preoperative serum creatinine of 1.0 mg/dL B. history of cerebrovascular accident C. preoperative treatment with insulin D. history of congestive heart failure E. major vascular surgery 1. A. The Revised Cardiac Risk Index identified six independent predictors of complications: high-risk type of surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, and preoperative serum creatinine above 2.0 mg/dL. (See page 572: Cardiovascular Disease.) 2. After an episode of asthma, airway hyperreactivity may persist up to: A. 24 hours B. 48 hours C. 72 hours D. 4 days E. several weeks 2. E. After an episode of asthma, airway hyperreactivity may persist for several weeks. (See page 579: Asthma.) 3. The current recommendation of the National Blood Resource Education Committee is that a hemoglobin of ________________
g/dL is acceptable in patients without systemic disease. A. 9 B. 6 C. 7 D. 10 E. 8 3. C. The current recommendation of the National Blood Resource Education Committee is that a hemoglobin of 7 g/dL is acceptable in patients without systemic disease. (See page 584: Complete Blood Count and Hemoglobin Concentration.) 4. Which of the following tests, if done preoperatively in a patient without risk factors, can lead to more harm than benefit? A. Electrocardiography (ECG) B. Blood urea nitrogen (BUN)/creatinine C. Chest radiography (CXR) D. Urinalysis (U/A) E. None of the above 4. C. A preoperative CXR can identify abnormalities that may lead to either a delay or a cancellation of the planned surgical procedure or modification of perioperative care. However, routine testing in the population without risk factors can lead to more harm than benefit. The American College of Physicians suggests that a CXR is indicated in the presence of active chest disease and before intrathoracic procedures but not solely on the basis of advanced age. (See page 585: Chest Radiography.) 5. Postoperatively, functional residual capacity may take up to ________________ to return to baseline. A. 24 hours B. 48 hours C. 3 days
D. 7 days E. 14 days 5. E. Functional residual capacity may take up to 2 weeks to return to baseline. (See page 578: Pulmonary Disease.) 6. As a general rule, oral medications should be given to the patient ________________ before arrival in the operating room. A. 60 to 90 minutes B. 30 to 60 minutes C. 20 minutes D. 10 minutes E. 5 minutes 6. A. As a general rule, oral medications should be given to the patient 60 to 90 minutes before arrival in the operating room. It is acceptable to administer oral drugs with up to 150 mL of water. Intravenous agents produce effects after a few circulation times, but for full effect, intramuscular medications should be given at least 20 minutes and preferably 30 to 60 minutes before the patient's arrival in the operating room. (See page 586: Pharmacologic Preparation.) 7. All of the following are true regarding patients with obstructive sleep apnea (OSA) EXCEPT: A. Chronic pulmonary hypertension and right heart failure may be present. B. Increased neck circumference is a risk factor. C. Patients with OSA are more susceptible to the respiratory depressant effects of narcotics. D. Initiation of continuous positive airway pressure (CPAP) preoperatively does not reduce the perioperative risk. E. Patients with OSA are considered to have difficult airways. 7. D. Patients with OSA have chronic sleep deprivation, with daytime hypersomnolence and even behavioral changes in children. Depending on the frequency and severity of events, OSA may lead to changes such as
chronic pulmonary hypertension and right heart failure. Increased neck circumference, body mass index above 35 kg/m2, severe tonsillar hypertrophy, and anatomic abnormalities of the upper airway are factors commonly associated with OSA. These patients are especially susceptible to the respiratory depressant and airway effects of sedatives, narcotics, and inhaled anesthetics. Preoperative initiation of CPAP reduces the perioperative risk, and the difficult airway algorithm should be followed, with emergency airway equipment readily available. (See page 579: Obstructive Sleep Apnea.) For questions 8 to 13, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 8. Which of the following place(s) a patient at risk for increased perioperative cardiovascular morbidity and should be considered in a preoperative evaluation? 1. Peripheral arterial disease 2. Diabetes mellitus 3. Hypertension with left ventricular hypertrophy (LVH) 4. Diminished exercise tolerance 8. E. Peripheral arterial disease has been shown to be associated with coronary artery disease in multiple studies; at least 60% of the patients scheduled for major vascular surgery exhibit at least one coronary vessel with critical stenosis. Although a critical coronary stenosis delineates an area of risk for developing myocardial ischemia, this area may or may not be the underlying cause for a perioperative myocardial infarction that occurs. In the ambulatory population, many infarctions are the result of acute thrombosis of a noncritical stenosis. Diabetes mellitus is common in elderly individuals, represents a disease that affects multiple organ systems, is associated with coronary artery disease, and increases the chance of silent myocardial ischemia and infarction. Hypertension can also be associated with an increased risk of silent myocardial ischemia and infarction, especially if the hypertension is associated with LVH with a strain pattern on electrocardiography. A strain pattern usually suggests a chronic ischemic state. An excellent exercise tolerance suggests that the myocardium can be stressed without failing.
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If patients experience dyspnea associated with chest pain during minimal exertion, the probability of extensive coronary artery disease is high; this has been associated with greater perioperative risk. (See page 572: Cardiovascular Disease.) 9. The hallmark features of Cushing syndrome include: 1. easy bruisability 2. truncal “thinning” 3. moon facies 4. hypotension 9. B. The prolonged use of glucocorticoids may lead to Cushing syndrome. Truncal obesity, moon facies, skin striations, easy bruisability, and hypertension are hallmark signs of Cushing syndrome. Preoperative preparations include correction of fluid and electrolyte abnormalities (e.g., hypokalemia, hyperglycemia). In patients with long-term corticosteroid use, perioperative steroid supplementation is indicated to cover the stress of anesthesia and surgery. (See page 580: Endocrine Disease.) 10. Which of the following should be included in the preoperative history to rule out a bleeding abnormality? 1. Easy bruising 2. Unusual bleeding after a tooth extraction 3. Liver disease 4. Use of chemotherapeutic agents 10. E. Coagulation disorders can have significant impact on the surgical procedure and perioperative management. Abnormal laboratory study results require preoperative evaluation of the patient; however, in the absence of a clinical bleeding diathesis, complications are extremely rare. Analyses of prothrombin time and partial thromboplastin time are indicated in the presence of previous bleeding disorders (e.g., after injuries, tooth extraction, or surgical procedures) and in patients with known or suspected liver disease, malabsorption or malnutrition, or taking certain medications (e.g., chemotherapeutic agents). (See page 584: Coagulation Studies.)
11. A preoperative electrocardiogram (ECG) should be ordered and evaluated in which of the following patient populations? 1. Patients with a prior myocardial infarction 2. Patients with a history of hypertension, diabetes mellitus, or peripheral vascular disease 3. Patients without cardiac risk factors who are about to undergo vascular surgery 4. Women older than age 70 years 11. E. The preoperative 12-lead ECG can provide important information on the status of the patient's myocardium and coronary circulation. Abnormal Q waves in high-risk patients are highly suggestive of a past myocardial infarction. Patients with Q-wave infarctions are known to be at increased risk of perioperative cardiac events and have worse longterm prognoses. Patients who exhibit left ventricular hypertrophy or ST segment changes on a preoperative ECG are also at an increased risk of perioperative cardiac events. Reasonable recommendations for a preoperative ECG include patients with systemic cardiovascular disease, diabetes mellitus, men older than age 60 years, women older than age 70 years, and patients with no clinical risk factors about to undergo vascular surgical procedures. (See page 576: Cardiovascular Tests and page 574: Table 23-4.) 12. TRUE statements about cessation of smoking include: 1. Stopping for 48 hours reduces the amount of carboxyhemoglobin. 2. Cessation between 48 hours and 6 weeks is associated with increased mucociliary clearance. 3. Cessation for 48 hours abolishes the effects of nicotine. 4. Stopping for 1 week is sufficient to eliminate the increased incidence of postoperative pulmonary complications. 12. B. Cessation of smoking for 2 days may decrease carboxyhemoglobin levels, abolish the effects of nicotine, and improve mucous clearance. Between 2 days and 6 weeks, there is no real improvement because mucociliary clearance does not improve during this time. A prospective
study showed that smoking cessation for at least 8 weeks was necessary to reduce the rate of postoperative pulmonary complications. (See page 579: Tobacco.) 13. A resting echocardiogram provides information about: 1. ventricular function 2. regional wall motion 3. ventricular wall thickness 4. valvular function 13. E. A resting echocardiogram can determine the presence of ventricular dysfunction, regional wall abnormalities, ventricular wall thickness, and valvular function. Pulsed-wave Doppler can be used to obtain the velocity–time integral. Ejection fraction then can be calculated by determining the cross-sectional area of the ventricle. (See page 576: Assessment of Ventricular and Valvular Function.)
Chapter 24 Malignant Hyperthermia and Other Inherited Disorders 1. What is the earliest sign of malignant hyperthermia (MH) in an intubated, paralyzed patient? A. Ventricular arrhythmia B. Tachycardia C. Tachypnea D. Fever E. Increased end-tidal CO2 1. E. Elevation of end-tidal CO2 is one of the earliest signs of MH. Tachypnea does not occur in intubated, paralyzed patients. Tachycardia and hypertension result from sympathetic nervous system stimulation secondary to underlying hypermetabolism and hypercarbia. Ventricular dysrhythmias may occur and are induced by sympathetic nervous system stimulation, hypercarbia, hyperkalemia, or catecholamine release. (See page 599: Classic Malignant Hyperthermia.) 2. Which statement regarding masseter muscle rigidity (MMR) is TRUE? A. It is not associated with malignant hyperthermia (MH). B. MMR is only seen in children. C. MMR most commonly occurs after administration of succinylcholine (Sch) after administration of an intravenous (IV) induction agent. D. It is predictive of MH susceptibility in up to 25% of cases. E. Repeat doses of a depolarizing muscle relaxant relieve MMR.
2. D. Although MMR probably occurs in patients of all ages, it is more common in children and young adults. In most cases of MMR, anesthesia was induced by inhalation of halothane or sevoflurane after which Sch was administered. Although less common, MMR may occur after Sch administration after IV induction. MMR may even occur after induction with any IV or inhalation anesthetic agent. Repeat doses of Sch do not relieve MMR, and nondepolarizing relaxants do not reliably relieve MMR. (See page 600: Masseter Muscle Rigidity.) For questions 3 to 13, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 3. Which of the following are signs and symptoms of neuroleptic malignant syndrome? 1. Bradycardia 2. Hypertension 3. Flaccid paralysis 4. Acidosis 3. C. The symptoms and signs of neuroleptic malignant syndrome include fever, rhabdomyolysis, tachycardia, hypertension, agitation, muscle rigidity, and acidosis. The mortality rate is unknown but may be significant. Dantrolene is an effective therapeutic modality in many cases of neuroleptic malignant syndrome. (See page 602: Neuroleptic Malignant Syndrome and Other Drug-Induced Hyperthermia Reactions.) 4. Which of the following may occur during an episode of malignant hyperthermia (MH)? 1. Hyperkalemia 2. Myoglobinuria 3. Lactic acidosis 4. Hypocalcemia 4. A. Hyperkalemia, hypercalcemia, lactic acidosis, and myoglobinuria are characteristic of MH episodes. A mixed venous sample will show even
more dramatic evidence of increased CO2 production and metabolic acidosis. (See page 599: Classic Malignant Hyperthermia.) 5. Which of the following statements regarding masseter muscle rigidity (MMR) are TRUE? 1. It is most commonly seen in children. 2. Peripheral nerve stimulation typically does not reveal muscle relaxation. 3. Tachycardia is frequent. 4. Repeat doses of succinylcholine (Sch) cause relaxation. 5. B. Although MMR probably occurs in patients of all ages, it is distinctly most common in children and young adults. Several studies have shown a peak incidence at age 8 to 12 years. A peripheral nerve stimulator on the arm usually reveals flaccid paralysis. However, increased tone of other muscles may also be noted. Repeat doses of Sch do not relieve the problem. Tachycardia and dysrhythmias are frequent. (See page 600: Masseter Muscle Rigidity.) 6. Which of the following should be considered as a possibility in the differential diagnosis of masseter muscle rigidity (MMR)? 1. Myotonic syndrome 2. Low dose of succinylcholine (Sch) 3. Insufficient time to intubation after Sch administration 4. Temporomandibular joint (TMJ) syndrome 6. E. The differential diagnosis of MMR includes myotonic syndrome, TMJ dysfunction, underdosing with Sch, or not allowing sufficient time for Sch to act before intubation. (See page 600: Masseter Muscle Rigidity.) 7. Which of the following statements regarding neuroleptic malignant syndrome are TRUE? 1. Symptoms usually occur after an acute exposure to a triggering agent. 2. Haloperidol is a cause. 3. Bromocriptine administration often precipitates this disorder.
4. Sudden withdrawal of levodopa may cause onset of symptoms. 7. C. Although the resemblance of neuroleptic malignant syndrome to malignant hyperthermia (MH) is striking, there are significant differences between the two disorders. MH is acute, but neuroleptic malignant syndrome often occurs after long-term drug exposure. Phenothiazines and haloperidol or other antipsychotic agents are the usual triggering agents for neuroleptic malignant syndrome. Sudden withdrawal of drugs used to treat Parkinson's disease may also trigger neuroleptic malignant syndrome. Electroconvulsive therapy with succinylcholine does not appear to trigger the syndrome. A variety of drugs have been found useful in the treatment of neuroleptic malignant syndrome, including benzodiazepines, bromocriptine, and dantrolene. (See page 602: Neuroleptic Malignant Syndrome and Other Drug-Induced Hyperthermia Reactions.) 8. Which of the following can trigger malignant hyperthermia (MH)? 1. Ether 2. Succinylcholine (Sch) 3. Methoxyflurane 4. Decamethonium 8. E. It is clearly established that potent inhalational agents, including sevoflurane, desflurane, isoflurane, halothane, methoxyflurane, cyclopropane, and ether, may trigger MH. Sch and decamethonium (depolarizing muscle relaxants) also are triggers. (See page 602: Drugs That Trigger Malignant Hyperthermia.) 9. Which of the following statements regarding treatment of malignant hyperthermia (MH) are TRUE? 1. A reasonable initial dose of dantrolene is 2.0 to 2.5 mg/kg. 2. Calcium channel blockers are useful in acute phase treatment. 3. Lidocaine is effective in managing dysrhythmias. 4. The recommended maximum dose of dantrolene is 7.5 mg/kg. 9. B. Initial intravenous therapy should be started with a minimum dose of 2.5 mg/kg, with repeat doses as needed. Although it has been
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recommended that the maximum dose of dantrolene is 10 mg/kg, more should be given as dictated by clinical circumstances. Dysrhythmia control usually occurs after hyperventilation, dantrolene therapy, and correction of acidosis. Lidocaine can be safely used during MH crises. Calcium channel blockers should not be used in the acute treatment of MH. Several studies have shown that verapamil may interact with dantrolene to produce hyperkalemia and myocardial depression. (See page 606: The Treatment of Malignant Hyperthermia.) 10. Which of the following statements regarding dantrolene are TRUE? 1. It acts intracellularly. 2. It inhibits excitation contraction coupling. 3. In usual clinical doses, it has little effect on myocardial contractility. 4. It increases the reuptake of intracellular calcium. 10. A. Dantrolene acts within the muscle cell itself by reducing intracellular levels of calcium. This most likely results from a reduction of calcium release by the sarcoplasmic reticulum. In usual clinical doses, dantrolene has little effect on myocardial contractility. (See page 607: Dantrolene.) 11. Which of the following may result in legal judgment in favor of the plaintiff if an episode of malignant hyperthermia (MH) occurs? 1. Failure to obtain a complete history 2. Not having a temperature monitor 3. Having an inadequate supply of dantrolene 4. Not investigating unexplained fever 11. E. Most of the common themes underlying the basis of litigation in MH cases include failure to obtain a thorough personal history, failure to continuously monitor temperature, failure to have an adequate supply of dantrolene, and failure to investigate an unexplained increase in body temperature. (See page 608: Medicolegal Aspects.) 12. Which of the following statements regarding porphyria are TRUE?
1. It is a defect in heme synthesis. 2. Inducible porphyria may cause a neurologic syndrome. 3. Conjugation of succinyl coenzyme A is the limiting step. 4. All barbiturates are contraindicated in patients with porphyria. 12. E. All the porphyrias result from a defect in heme synthesis. The very limiting step in heme synthesis is the conjugation of succinyl coenzyme A with glycine to form D-aminolevulinic acid. The inducible porphyrias are those in which the acute symptoms are precipitated during drug exposure. These porphyrias may cause an acute neurologic syndrome. Barbiturates are contraindicated in patients with porphyria. (See page 615: The Porphyrias.) 13. Which of the following may be characteristic of glucose-6phosphate deficiency? 1. Hyperglycemia 2. Poor tolerance to fasting 3. Alkalosis 4. Prolonged bleeding time 13. C. Glucose-6-phosphate deficiency is an autosomal recessive disorder. The prognosis is moderately good, with many patients surviving into adulthood. These patients tolerate fasting very poorly. Hypoglycemia, acidosis, and convulsions may be problems. Prolonged bleeding time has been described. (See page 617: Defects in Glucose Metabolism.)
Chapter 25 Rare and Co-existing Diseases 1. Which of the following statements about Duchenne muscular dystrophy is TRUE? A. The underlying defect is the lack of the muscle protein dystrophin, a major component of the muscle membrane. B. Cardiac muscle is spared from the disease process. C. Painful degeneration and atrophy of skeletal muscle is a hallmark of the disease. D. It is a genetic dominant trait. E. Death rarely occurs. 1. A. Duchenne muscular dystrophy is a sex-linked recessive disorder that is evident in boys and young men. In Duchenne muscular dystrophy, the underlying defect is a lack of the muscle protein dystrophin. Progressive painless muscle degeneration with atrophy of skeletal muscle occurs. Cardiac muscle and smooth muscle are not spared. Pneumonia and congestive heart failure are common causes of death, which may occur between the ages of 15 and 25 years. (See page 622: Duchenne Muscular Dystrophy.) 2. Anesthetic management of patients with muscular dystrophy involves attention to all of the following EXCEPT: A. myocardial depressant sensitivity to inhalational agents B. avoidance of succinylcholine (Sch) secondary to massive release of potassium C. malignant hyperthermia precautions D. use of high doses of nondepolarizing muscle relaxants (NDMRs) because of resistance to these drugs E. use of drugs for aspiration precautions
2. D. Patients with muscular dystrophy have increased susceptibility to the myocardial depressant effects of inhalation anesthetics. Use of NDMRs should be modified because of increased sensitivity to these drugs from pre-existing muscle weakness. Use of Sch may result in increased potassium secondary to membrane instability. Some patients with muscular dystrophy may be susceptible to malignant hyperthermia, but this is unpredictable. Smooth muscle involvement causes intestinal hypomobility, delayed gastric emptying, and gastroparesis. (See page 622: Muscular Dystrophy: Management of Anesthesia.) 3. All of the following statements about myotonia are true EXCEPT: A. Myotonia results in delayed skeletal muscle relaxation. B. Myotonia diseases are similar to muscular dystrophy in that the underlying defect is a membrane-stabilizing protein. C. Reversal with neostigmine may provoke a myotonic contracture. D. Pulmonary function studies demonstrate a restrictive type of lung disease pattern. E. There are two types of myotonic dystrophy that are caused by abnormalities in two distinct gene loci. 3. B. The myotonias are a group of illnesses characterized by delayed relaxation of skeletal muscle. There are two types of myotonic dystrophies that are caused by abnormalities in two different gene loci. Myotonic dystrophy is the most common form. The underlying defect is secondary to defects in sodium channels that alter ion channel function. Reversal with neostigmine may provoke a myotonic contracture. Pulmonary function studies demonstrate a restrictive type of lung disease pattern, mild arterial hypoxia, and diminished ventilatory response to hypoxia and hypercapnia. (See page 624: Myotonias.) 4. What is an important consideration in the anesthetic management of patients with familial periodic paralysis? A. Maintenance of hypokalemia in all forms of myotonia B. Use of succinylcholine (Sch) is acceptable in the presence of normokalemia
C. Maintaining mild hypothermia D. No change in dosing of nondepolarizing muscle relaxants (NDMRs) E. Avoidance of large carbohydrate loads 4. E. Familial periodic paralysis includes a subgroup of skeletal muscle channelopathies. This group includes hyperkalemic, hypokalemic, paramyotonic congenital, normokalemic periodic paralysis, and potassium-aggravated myotonia. All have persistent sodium inward current depolarization causing membrane inexcitability and subsequent muscle weakness. Anesthetic management consists of maintenance of a normal potassium level and avoiding precipitating weakness. During episodes of weakness, patients are more sensitive to NDMRs. Sch should be avoided to prevent changes in serum potassium levels. Serial potassium measurements during the perioperative period are recommended. Avoidance of hypothermia and of large carbohydrate loads is also recommended. (See page 625: Familial Periodic Paralysis.) 5. All of the following statements about myasthenia gravis are true EXCEPT: A. It is a disease of the neuromuscular junction involving the muscarinic acetylcholine (Ach) receptors. B. It is an autoimmune disorder with the production of antibodies against Ach receptors. C. The mainstay of medical therapy involves the cholinesterase inhibitor pyridostigmine, corticosteroids, immunosuppressive agents, and intravenous immunoglobulin. D. The hallmark of myasthenia gravis is skeletal muscle weakness. E. The process most likely originates in the thymus gland. 5. A. Myasthenia gravis is a disease of the neuromuscular junction in which antibodies are formed against the nicotinic Ach receptors; Thelper cells assist in this antibody production. The hallmark of myasthenia gravis is skeletal muscle weakness. The disease probably originates in the thymus gland; 90% of patients have histiologic abnormalities such as thymoma, thymic hyperplasia, or thymic atrophy. Thymectomy may help in controlling the symptoms. The mainstay
therapy is medical treatment with the cholinesterase inhibitor pyridostigmine. Other treatment modalities may include corticosteroids, immunosuppressants, plasmapheresis, and thymectomy. (See page 626: Myasthenia Gravis.) 6. Intraoperative management of myasthenia gravis may include all of the following EXCEPT: A. consideration of increased sensitivity to nondepolarizing muscle relaxants (NDMRs) B. use of a defasciculating dose of NDMR to facilitate intubation C. use of a short-acting NDMR with neuromuscular monitoring D. consideration of resistance to succinylcholine (Sch) E. use of an anesthetic technique that avoids the use of muscle relaxants 6. B. Patients with myasthenia gravis are exquisitely sensitive to NDMRs, so a defasciculating dose of an NDMR may result in excessive muscle relaxation. Use of a short-acting NDMR is recommended to avoid prolonged postoperative paralysis. Response to Sch includes greater resistance and prolonged duration of action (which may partially be attributable to use of pyridostigmine in the treatment of the disease). Use of regional anesthesia may avoid respiratory depression associated with opioids. Use of an anesthetic technique that avoids use of muscle relaxants may be useful. (See page 626: Myasthenia Gravis: Management of Anesthesia.) 7. All of the following statements about Lambert-Eaton syndrome are true EXCEPT: A. It is a disorder of neuromuscular transmission associated with carcinomas. B. Antibodies against the acetylcholine (Ach) receptor are produced. C. Treatment involves treating the underlying malignancy. D. 3,4-Diaminopyridine may be used in the treatment to increase release of Ach.
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E. A typical patient is a man older than age 40 years with proximal extremity weakness. 7. B. Lambert-Eaton syndrome is a disorder of neuromuscular transmission associated with carcinomas, especially small cell carcinoma of the lung. A typical patient is a man older than age 40 years with proximal extremity weakness. The onset may precede detection of carcinoma by years. Immunoglobulin G antibodies are produced against presynaptic calcium channels; this inhibits the proper release of Ach. Autonomic dysfunction may also occur. Patients are sensitive to both depolarizing muscle relaxants and nondepolarizing muscle relaxants. In addition to treating the underlying malignancy, the most effective symptomatic therapy includes 3,4-diaminopyridine, which improves synaptic transmission by opening voltage-gated potassium channels and increasing release of Ach. Pyridostigmine may also be used to treat symptoms of weakness. Treatment may also include immunoglobulin and plasmapheresis. (See page 627: Myasthenic Syndrome [Lambert-Eaton Syndrome].) 8. Which of the following statements about Guillain-Barré syndrome (polyradiculoneuritis) is TRUE? A. It is an autoimmune disorder triggered by a bacterial or viral infection. B. The autoimmune response is against myocytes of skeletal muscle. C. Ventilatory support is rarely needed. D. Eighty-five percent of patients do not recover. E. Administration of succinylcholine (Sch) is not associated with hyperkalemia. 8. A. Guillain-Barré syndrome is an autoimmune disorder triggered by bacterial or viral infections. Antibodies are produced against myelin, which results in demyelination of nerve tissue. Symptoms include subacute or acute skeletal muscle weakness, which may result in respiratory compromise. Prognosis is good, with 85% of patients achieving full recovery. Treatment consists of plasmapheresis or highdose immunoglobulin. Patients are exquisitely sensitive to Sch, so this
drug should be avoided. This response may persist after symptoms have resolved. (See page 628: Guillain-Barré Syndrome.) 9. Multiple sclerosis may have all of the following anesthetic considerations EXCEPT: A. Patients with multiple sclerosis should be advised that an exacerbation of their neurologic symptoms may occur during the perioperative period. B. It is speculated that demyelinated areas of the spinal cord are more sensitive to the neurotoxicity of local anesthetics. C. A thorough neurologic examination before surgery or anesthesia is helpful. D. Autonomic dysfunction is not a concern in patients with multiple sclerosis. E. Multiple sites of demyelination of the brain and spinal cord are the hallmarks of the disease. 9. D. Multiple sclerosis is an acquired disease of the central nervous system (CNS) that results in demyelination of the brain and spinal cord. The cause is multifactorial, and the disease occurs in genetically susceptible individuals. A viral cause has been suspected but not proven. Symptoms of multiple sclerosis are related to the site of demyelination. It is speculated that demyelinated areas of the spinal cord are sensitive to the neurotoxicity of local anesthetics. The course of the disease process is characterized by waxing and waning of symptoms. Therapy for patients with multiple sclerosis is directed at modulating the immunologic and inflammatory responses that damage the CNS. Corticosteroids are used to control acute exacerbations of symptoms but have no influence on long-term outcome. Corticosteroids have diverse effects that suppress cellular immune responses and inflammatory edema. Other treatments include interferon, glatiramer, mitoxantrone, and symptomatic treatment with baclofen and carbamazepine. Interferon alters the inflammatory response, augments natural disease suppression, and has been shown to reduce the relapse rate. Mitoxantrone, which may be cardiotoxic, can be used to treat patients with aggressive multiple sclerosis. Patient response to immunosuppressants has been variable. Patients with multiple sclerosis
should be advised that an exacerbation of their neurologic symptoms may occur during the perioperative period. A thorough neurologic examination before surgery or anesthesia is helpful. Hyperthermia and metabolic and hormonal changes induced by surgery or anesthesia may exacerbate symptoms. Autonomic dysfunction caused by multiple sclerosis may exaggerate the hypotensive effects of volatile anesthetics. (See page 628: Multiple Sclerosis.) 10. All of the following statements concerning epilepsy are true EXCEPT: A. Many different types of central nervous system (CNS) disorders may cause excessive discharge of neurons to synchronously depolarize and thereby generate seizures. B. Grand mal seizures are characterized by tonic-clonic motor activity with respiratory arrest and hypoxemia. C. In status epilepticus, skeletal muscle activity diminishes over time, and seizure activity can only be detected on electroencephalography (EEG). D. Use of ketamine for induction is a reasonable choice. E. Maintenance of chronic antiseizure medication is critical throughout the perioperative period. 10. D. Seizures may be the manifestation of many disorders of the CNS. Seizures result from excessive discharge of neurons that synchronously depolarize. Symptoms are related to the area of neuronal activity. There are more than 40 different types of epilepsy based on the clinical features. Grand mal seizures are characterized by tonic-clonic motor activity that results in respiratory arrest and arterial hypoxemia. Patients with status epilepticus have recurrent grand mal seizures with loss of consciousness lasting more than 30 minutes; mortality is high unless the condition is treated effectively. In status epilepticus, skeletal muscle activity diminishes over time, and seizure activity can only be seen on EEG. Lack of muscular activity may confuse and prevent proper diagnosis as a seizure progresses. During the perioperative period, antiseizure medication should be continued. In the event of seizure activity, benzodiazepines are the drug of choice for treatment. Use of muscle relaxants abolishes muscular activity; however, CNS neuronal
activity continues. Ketamine and methohexital may produce seizures in patients with known seizure disorders. (See page 629: Epilepsy.) For questions 11 to 20, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 11. Anesthetic management of patients with a medically treated seizure disorder involves which of the following considerations? 1. Sevoflurane may be epileptogenic, but the significance of this is not certain. 2. Patients receiving phenytoin or carbamazepine exhibit resistance to nondepolarizing muscle relaxants. 3. Potent opioids may produce myoclonic activity or chest wall rigidity, which can be confused with seizure activity. 4. Use of ketamine for induction is indicated. 11. A. Most inhaled anesthetics, including nitrous oxide, have been reported to produce seizure activity, but it is rare with isoflurane and desflurane. Sevoflurane may be epileptogenic, but the clinical significance is uncertain. There is a potential for significant drug interaction for the same reason. Potent opioids may produce myoclonic activity or chest wall rigidity, which may be confused with seizure activity. Use of ketamine may produce seizure-like activity, so this drug is relatively contraindicated in these patients because better alternative medicines exist. Patients receiving phenytoin or carbamazepine exhibit resistance to nondepolarizing muscle relaxants. (See page 629: Epilepsy: Management of Anesthesia.) 12. Which of the following statements regarding Parkinson's disease are TRUE? 1. It is a disease of the central nervous system characterized by destruction of dopamine-containing nerve cells in the substantia nigra of the basal ganglion. 2. Parkinson's disease is commonly caused by a virus. 3. γ -Aminobutyric acid (GABA) levels increase with resultant suppression of cortical motor function.
4. Decreasing dopamine levels in the brainstem result in resolution of symptoms. 12. B. Parkinson's disease is a disabling neurologic disease that primarily affects adults older than 65 years of age. It is characterized by the destruction of dopamine-containing nerve cells in the substantia nigra of the basal ganglia of the brain. Deficiency of dopamine results in increases in activity of GABA. This acid results in inhibition of brainstem nuclei, which suppress cortical motor function. This causes the characteristic features of the disease, such as resting tremor, akinesia, and postural abnormalities. Treatment of the disease is directed at increasing dopamine levels in the brain with minimal peripheral side effects. The etiology of Parkinson's disease is multifactorial, with genetic and environmental factors. It may also develop after encephalitis. There is little evidence for a viral cause. (See page 630: Parkinson's Disease.) 13. Management of anesthesia in patients with Parkinson's disease includes which of the following? 1. Use of phenothiazines and butyrophenones is contraindicated. 2. Gastrointestinal dysfunction is manifested by salivation, dysphagia, and esophageal dysfunction. 3. Autonomic dysfunction is a common manifestation. 4. Drug therapy should be discontinued before induction of anesthesia. 13. A. In Parkinson's disease, use of butyrophenones (droperidol) and phenothiazines is contraindicated because of their effects on dopamine levels in the central nervous system. Autonomic dysfunction is common; symptoms include orthostatic hypotension, gastrointestinal dysfunction, and an exaggerated response to inhalational agents. Drug therapy should not be discontinued because muscular rigidity may interfere with the ability to extubate a patient. Gastrointestinal manifestations include dysphagia, esophageal dysfunction, and salivation. Patients with Parkinson's disease should be considered at risk of aspiration pneumonitis. (See page 630: Parkinson's Disease.)
14. Which of the following statements regarding Huntington's chorea are TRUE? 1. Disordered movement and dementia are clinical hallmarks of the disease. 2. Mental depression and suicide are common. 3. Specific therapy is directed at control of the movement disorder. 4. Duration of disease averages 17 years from the time of diagnosis to death. 14. E. Huntington's disease is a neurodegenerative disease of the corpus striatum and cerebral cortex. It is an inherited disorder that is autosomal dominant. Clinical symptoms include disordered movement, dementia, clinical depression, athetosis, and dystonia. Mental depression and suicide are common. The duration of the disease averages approximately 17 years from diagnosis to death. There is no specific therapy; treatment is directed at both depression and control of movement disorders. (See page 631: Huntington's Disease.) P 15. Amyotrophic lateral sclerosis is manifested by which of the following? 1. It is a degenerative disease involving motor cells of the central nervous system (CNS). 2. Although the cause is unknown, glutamate excitotoxicity and oxidant stress secondary to exposure to metal toxicity or environmental toxins are hypothesized factors. 3. There is an increased sensitivity to nondepolarizing muscle relaxants (NDMRs). 4. There is sparing of pulmonary function. 15. A. Amyotrophic lateral sclerosis is a degenerative disease of the anterior horn cell (motor cells) throughout the CNS. It is believed to be viral in origin and bears similarity to poliomyelitis. Glutamate excitotoxicity and oxidant stress secondary to exposure to toxic metals or other environmental toxins have been implicated. It is a rapidly
progressive disorder in which death results within 3 to 5 years of diagnosis. Pulmonary function is severely affected, with all patients eventually requiring mechanical ventilation. Neuromuscular transmission is altered, and patients have increased sensitivity to NDMRs. These patients may also exhibit a hyperkalemic response to succinylcholine because of the emergence of extrajunctional acetylcholine receptors. (See page 632: Amyotrophic Lateral Sclerosis.) 16. Which of the following facts should be considered when anesthetizing a patient with anemia? 1. Healthy individuals do not develop symptoms until hemoglobin (Hgb) levels decrease to below 7 g/dL. 2. Physiologic compensation includes increased plasma volume, increased cardiac output, and increased 2,3-diphosphoglycerate (2,3-DPG) levels. 3. Symptoms are highly variable and depend on concurrent disease processes and the speed of developing anemia. 4. There is no accepted Hgb level at which transfusion should be administered. 16. E. There are numerous causes of anemia. Compensations include an increase in plasma volume, cardiac output, and 2,3-DPG levels as well as decreased viscosity. Symptoms depend on concurrent disease processes, and most healthy individuals can tolerate an Hgb level of 7 g/dL without significant symptoms. No specific Hgb level exists below which a transfusion should be administered. Concurrent disease and the need for increased oxygen-carrying capacity influence the need for transfusion. (See page 632: Anemias.) 17. Which of the following facts are TRUE regarding nutritional deficiency anemias? 1. All deficiency anemias result in microcytic hypochromic red blood cells (RBCs). 2. Deficiency anemias can be categorized into three subtypes based on the cause: iron deficiency, vitamin B12, and folic acid.
3. The use of nitrous oxide (N2O) is contraindicated in patients with iron deficiency anemia. 4. Causes of folic acid deficiency include alcoholism, pregnancy, and malabsorption syndromes. 17. C. Nutritional deficiency anemias are categorized into three subtypes: iron, vitamin B12, and folic acid deficiency. Only iron deficiency anemia produces RBCs that are microcytic and hypochromic. This anemia may be from poor iron intake or from rapid turnover of RBCs. Hemoglobin and ferritin levels are good clinical tests for iron deficiency. In vitamin B12 and folate deficiency, the RBCs are enlarged. Causes of folic acid deficiency include alcoholism, pregnancy, and malabsorption syndromes. N2O is not contraindicated in iron deficiency anemia. The clinical significance of an N2O effect on vitamin B12 metabolism is controversial. (See page 632: Nutritional Deficiency Anemia.) 18. Which of the following statements regarding hemolytic anemias are TRUE? 1. Spherocytosis is a disorder of the hemoglobin-carrying capacity of the red blood cell (RBC). 2. Glucose-6-phosphate dehydrogenase (G6PD) deficiency results in an inability to reduce methemoglobin; therefore, sodium nitroprusside is contraindicated. 3. The life span of an RBC in a patient with hereditary spherocytosis is 120 days. 4. Splenectomy may be indicated in patients with hereditary spherocytosis. 18. C. Hereditary spherocytosis is a disorder of the proteins that comprise the skeleton of the RBC membrane and renders the membrane unstable; this predisposes the patient to chronic hemolysis. G6PD deficiency is a hemolytic disorder in which nicotinamide adenine dinucleotide phosphate (NADPH) is not produced. This results in an increased sensitivity to oxidation. G6PD deficiency also results in a reduced level of glutathione. The cells become rigid, which accelerates clearance by the spleen. Numerous drugs induce hemolysis. Patients
with G6PD deficiency are unable to reduce methemoglobin, so nitroprusside and prilocaine should not be administered. Treatment of patients with hereditary spherocytosis consists of a splenectomy; however, splenectomy is rarely indicated before age 6 years because of the high incidence of pneumococcal infection. The life span of a normal RBC is 120 days. Because the RBC membrane in hereditary spherocytosis is altered, the life span of the RBC is shortened. (See page 633: Hemolytic Anemias.) 19. Anesthetic management of a patient with sickle cell disease (SCD) involves which of the following? 1. Adequate systemic oxygenation and hydration 2. Maintenance of the hematocrit between 40% and 42% is optimal 3. Maintenance of normothermia for all types of surgery 4. Always avoiding tourniquets 19. B. SCD is a hereditary disorder associated with the formation of abnormal hemoglobin (Hgb). This Hgb has the tendency to sickle under specific environmental conditions (e.g., hypoxia, hypothermia, and acidosis). Individuals who are homozygous have a greater tendency to develop sickling because of the greater proportion of abnormal Hgb. Arterial tourniquets have been used safely in patients with SCD; however, these devices should be used only when they are critical to the surgical procedure because of the possibility of local hypoxia and acidosis. Most commonly used anesthetic medications do not have an effect on the sickling process. Maintenance of a hematocrit between 30% and 35% is desired. (See page 634: Sickle Cell Disease.) 20. Which of the following statements concerning rheumatoid arthritis are TRUE? 1. It is characterized by chronic inflammation of multiple organ systems. 2. Polyarthropathy is the hallmark of the disease. 3. Rheumatoid arthritis is a multisystem disease that causes subclinical cardiac and pulmonary dysfunction.
4. Rheumatoid arthritis may affect the joints of the larynx with generalized edema and limitation of vocal cord movement. 20. E. Rheumatoid arthritis is a chronic inflammatory disease with symmetric polyarthropathy and involvement of other systemic organs. It often causes subclinical cardiac and pulmonary dysfunction. Polyarthropathy initially occurs in the hands and wrists but may involve the joints of the lower extremities, atlantoaxial joints, temporomandibular joint, cervical spine, and joints of the larynx. Involvement of the larynx may result in generalized edema and limitation of vocal cord movement. Other potential systemic manifestations include pericarditis, aortitis, pulmonary nodules, interstitial lung disease, renal failure, and anemia. Felty syndrome is the clinical triad of rheumatoid arthritis, leukopenia, and hepatosplenomegaly. (See page 636: Rheumatoid Arthritis.)
Chapter 26 The Anesthesia Workstation and Delivery Systems 1. The anesthesia machine has been redefined by the American Society for Testing and Materials (ASTM). What is the new term? A. Anesthesia pump system B. Anesthesia supply station C. Anesthesia workstation D. Anesthesia sleep station E. Magic sleeping machine 1. C. Modern anesthesia systems administer anesthetics by a gas supply system and ventilator. There are also built-in monitors and protection devices. This integration of technologies is now termed the “anesthesia workstation” by the ASTM. Although the unit is a variation of a pump and it does supply anesthetics, these two labels are incomplete. Our surgical colleagues sometimes refer to the unit as a “magic sleeping machine,” but this is also inaccurate. (See page 645: Anesthesia Workstation Standards and Pre-Use Procedures.) 2. To comply with the 2005 American Society for Testing Materials (ASTM) standards, newly manufactured anesthesia work stations must have all of the following EXCEPT: A. exhaled tidal volume monitors B. anesthetic vapor concentration monitors C. a prioritized alarm system D. a way to measure supplied O2 pressure E. a low-pressure circuit leak alarm 2. E. To comply with the 2005 ASTM standards, newly manufactured workstations must have monitors that measure the following
parameters: continuous breathing system pressure, exhaled tidal volume, ventilatory CO2 concentration, anesthetic vapor concentration, inspired O2 concentration, O2 supply pressure, arterial hemoglobin oxygen saturation, arterial blood pressure, and continuous electrocardiogram. The anesthesia workstation must have a prioritized alarm system that groups alarms into three categories: high, medium, and low priority. (See page 646: Standards for Anesthesia Machines and Workstations.) 3. Considering the O2 cylinder supply source, which of the following statements is TRUE? A. Anesthesia machines hold reserve D cylinders. B. The hanger yoke assemblies that attach the cylinders to the anesthesia machine are equipped with a pin index safety system to eliminate cylinder interchange. C. The cylinder supply source is the primary gas source for the anesthesia machine. D. A cylinder exchange cannot take place while gas is flowing from another cylinder into the machine. E. The cylinder should be left open when the machine is in use in case of a pipeline failure. 3. B. The anesthesia machines hold reserve E cylinders if a pipeline supply source is not available or if the pipeline fails. Each hanger yoke is equipped with the pin index safety system, which is a safeguard that eliminates cylinder interchanging and the possibility of accidentally placing the incorrect gas on a yoke designed to accommodate another gas. A check valve is located downstream from each cylinder. It minimizes gas transfer from a cylinder at high pressure to one with low pressure. It also allows an empty cylinder to be exchanged for a full one while gas continues to flow from another cylinder. The cylinder should be turned off except during the preoperative machine checking period or when a pipeline source is unavailable. (See page 654: Cylinder Supply Source.) 4. Piston-type anesthesia ventilators use less oxygen per minute than conventional gas-driven ventilators: True or false?
4. True. Pneumatic gas-driven ventilators consume more oxygen from pipeline sources or cylinder sources than piston-type ventilators or ventilating by hand. (See page 654: Cylinder Supply Source.) 5. If there is a suspected pipeline crossover malfunction (non-oxygen gas is substituted into the oxygen designated pipeline), what action should the anesthesia provider take? A. Nothing. The oxygen E-cylinder is already on, and it will automatically provide an oxygen source to the patient. B. Simply switch on the backup E-cylinder oxygen source. C. Switch on the backup E-cylinder source and disconnect the pipeline gas sources until the gases being piped in are identified. D. None of the above. 5. C. This situation is a good example of why understanding the underlying details of anesthesia equipment design and function is essential in caring for anesthetized patients. Intuitively, the correct action is to have the backup E cylinder in the “on” position at all times to provide an automatic source of 100% oxygen; however, this would lead to an undetected exhausted oxygen backup supply. The second intuitive answer is to switch on the backup supply when a gas pipeline crossover event is suspected; however, this would ignore that the pressure difference between pipeline and E cylinder regulators ensures a preferential supply from the compromised pipeline. (See page 653: Pipeline Supply Source.) 6. The flow meter assembly includes all of the following EXCEPT: A. a physically distinguishable O2 flow control knob B. a high-flow alarm to prevent turbulent flow C. a series arrangement when two flow tubes are present for a single gas D. float stops at the top and bottom of the flow tubes E. flow meter scales individually hand calibrated using a specific float
6. B. Contemporary flow control valve assemblies have numerous safety features. The O2 flow control knob is physically distinguishable from other gas knobs. It is distinctively fluted, projects beyond the control knobs of the other gases, and is larger in diameter than all the other flow control knobs. If a single gas has two flow tubes, the tubes are arranged in series and are controlled by a single control valve. Flow tubes are equipped with float stops at the top and bottom of the tube. The upper stop prevents the float from ascending to the top of the tube and plugging the outlet. It also ensures that the float will be visible at maximum flows (instead of being hidden in the manifold). The bottom float provides a central foundation for the indicator when the flow control valve is turned off. Flow meter scales are individually hand calibrated using a specific float. There is no high-flow alarm to prevent turbulent flow. (See page 656: Components of Flow Meter Assembly.) 7. Considering the flush valve, which of the following statements is TRUE? A. Using it intraoperatively may lead to patient awareness. B. Using it intraoperatively may cause barotrauma, especially if it is used during the expiratory phase of positive-pressure ventilation. C. It is never suitable as a high-pressure O2 source for jet ventilation. D. Flow from the flush valve enters the low-pressure circuit upstream from the vaporizer. E. Using it never leads to retrograde flow. 7. A. The O2 flush valve is associated with several hazards. Improper use of a normally functional O2 valve may also result in problems. Overzealous intraoperative O2 flushing may dilute inhaled anesthetics and lead to patient awareness. O2 flushing during the inspiratory phase of positive-pressure ventilation may cause barotrauma. Flow from the O2 flush valve enters the low-pressure circuit downstream from the vaporizers and downstream from the Ohmeda machine check valve. Inappropriate preoperative use of the O2 flush valve to evaluate the lowpressure circuit for leaks may be misleading, particularly on the Ohmeda
machine, which has the check valve at the common outlet. Back pressure from the breathing circuit closes the check valve airtight, and large low-pressure circuit leaks may go undetected. Some machines, including the Ohmeda Modulus 2+, do not have check valves; thus, O2 may flow in retrograde fashion through an internal relief valve located upstream from the O2 flush valve. The O2 flush valve may provide a highpressure O2 source suitable for jet ventilation. (See page 660: Oxygen Flush Valve.) 8. Most modern vaporizers are classified as all of the following EXCEPT: A. out-of-circuit B. temperature compensated C. flow-over D. pressure compensated E. variable bypass 8. D. Most modern vaporizers, including the Ohmeda Tec 4, Tec 5, and Tec 7 along with the North American Drager Vapor 19.n and 20.n, are classified as variable bypass, flow-over, temperature-compensated, agent-specific, out-of-circuit vaporizers. Variable bypass refers to the method of regulating output concentration. As gas enters the vaporizer's inlet, the setting of the concentration control valve determines the ratio of flow that goes through the bypass chamber and through the vaporizing chamber. The gas channel to the vaporizing chamber flows over the liquid anesthetic and becomes saturated with vapor. Thus, flow-over refers to the method of vaporization. These vaporizers are temperature compensated because they are equipped with an automatic temperature-compensating device that maintains a constant vapor output over a wide range of temperatures. These vaporizers are also agent specific and out-of-circuit because they are designed to accommodate a single agent and to be located outside the breathing circuit. Most modern vaporizers are not pressure compensated. However, vaporizers for desflurane do need to be pressure compensated because desflurane has a vapor pressure that is three to four times that of other contemporary inhaled anesthetics. (See page 662: Variable Bypass Vaporizers.)
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9. When considering flow rate and vaporizer output, which of the following statements is TRUE? A. The vaporizer output is most consistent at extremes of flow rates. B. The output of variable bypass vaporizers is less than the dial setting at high flow rates. C. At high flow rates, the vaporizer output can be higher than the dial setting secondary to increased resistance to bypass flow. D. Incomplete mixing leads to the output being higher than the dial setting at extremely high flow rates. E. The low level of turbulence at low flow rates affects the number of molecules vaporized. 9. E. With a fixed dial setting, vaporizer output varies with the rate of gas flowing through the vaporizer. This variation is particularly notable at extremes of flow rates. The output of all variable bypass vaporizers is less than the dial setting at low flow rates ( Pulmonary diastolic pressure (PDP) 2. Ability to aspirate blood from the distal port when the PAC is wedged
3. Nonphasic PCOP tracing 4. Chest radiograph showing the catheter tip below the level of the left atrium 26. C. To use a PAC to estimate left ventricular end-diastolic pressure (LVEDP) through the measurement of PCOP, the PAC must be positioned in the lungs at a site where a continuous column of blood will be present from the tip of the catheter to the left atrium when the balloon is inflated. This condition occurs in west zone 3. A PAC positioned in west zone 2 will measure airway pressure during the respiratory cycle because the alveolar pressure exceeds the capillary pressure at peak inspiration. Conditions that increase west zones 2 and 1 (e.g., hypovolemia, positive end-expiratory pressure) may convert a properly placed PAC into an improperly placed one, rendering the PAC useless for pulmonary capillary wedge pressure monitoring. A PAC in west zone 4 will be compressed by interstitial pressure, which is greater than left atrial pressure and thus gives falsely elevated PCOP values. The following characteristics suggest that a PAC is not in west zone 3: PCOP > PDP (if no pulmonary hypertension is present), nonphasic PCOP tracing, and an inability to withdraw blood when wedged. The location of a PAC may be confirmed by lateral chest radiography to ascertain that the catheter tip is below the level of the left atrium. (See page 707: Alveolar–Pulmonary Artery Pressure Relationships.) 27. Pulmonary capillary occlusion pressure (PCOP) is not a valid reflection of left ventricular end-diastolic pressure (LVEDP) in which of the following conditions? 1. Ischemic left ventricle 2. Aortic regurgitation 3. Mitral valve stenosis 4. Prolonged Q-T interval 27. A. PCOP as an accurate estimation of LVEDP is predicated on normal LV compliance, the absence of aortic or mitral valve disease (aortic regurgitation, mitral stenosis, or mitral regurgitation), normal pulmonary airway pressures, normal size of pulmonary vascular bed, and normal pulmonary vascular resistance. Altering these assumptions results
in the inability to predict LV loading conditions with PCOP values. (See page 707: Intracardiac Factors.) 28. Factors that increase the risk of mortality after a pulmonary artery catheter (PAC)–induced pulmonary artery rupture include: 1. coagulopathy 2. pulmonary hypertension 3. heparinization 4. hypotension 28. A. Pulmonary artery rupture is a rare but serious and possibly fatal complication of a PAC. The risk of rupture is increased in patients with pulmonary hypertension. Mortality after the rupture is aggravated further in patients who are heparinized or coagulopathic. (See page 707: Complications of Pulmonary Artery Catheter Monitoring.) 29. Which of the following statements are TRUE? 1. Convection is heat loss resulting from contact with surfaces. 2. Radiation is heat loss resulting from infrared irradiation. 3. Conduction is heat loss resulting from movement of air. 4. Evaporation is heat loss resulting from energy required for vaporization of water. 29. C. Convection is the change in heat content resulting from the movement of air over the surface of the object. Conduction is the change in heat content resulting from the object's contact with another surface. Radiation is the change in heat content resulting from absorption or emission of photons. Evaporation is heat loss resulting from the vaporization of water. (See page 711: Temperature Monitoring.) 30. Which of the following statement(s) about pulse oximetry are true? 1. Pulse oximetry combines the technology of plethysmography and spectrophotometry. 2. Ambient light, nail polish, and motion may compromise the accuracy of pulse oximetry.
3. Electrocautery can interfere with pulse oximetry. 4. Pulse oximetry measures the fractional oxygen saturation. 30. A. Pulse oximetry combines the technology of plethysmography and spectrophotometry. Ambient light, nail polish, and motion may compromise the accuracy of pulse oximetry. Electrocautery may interfere with pulse oximetry. Whereas pulse oximetry measures the functional oxygen saturation, co-oximetry measures the fractional oxygen saturation. (See page 700: Pulse Oximetry.)
Chapter 28 Echocardiography 1. Understanding the principles of ultrasound and echocardiographic instrumentation is essential to optimizing image quality. Which of the following statements regarding image resolution is TRUE? A. Image resolution increases with long wavelength sound waves. B. The greatest axial resolution is offered by long pulses of highfrequency ultrasound. C. Broadening beam size improves the lateral and elevational resolution. D. High frame rates and high pulse repetition frequencies (PRF) enhance resolution. 1. D. The PRF is the rate at which sound pulses are triggered. The greater the PRF, the greater the number of scan lines that are emitted in a given period. This enhances the motion display. Short pulses of highfrequency ultrasound offer the greatest axial resolution but have a decreased tissue penetration. Because resolution is highest along the axial plane, echocardiographic measurements are most precise when taken parallel to the beam's axis. The frame rate is the frequency at which the sector is rescanned. A high frame rate improves the capture of movement. Increases in sector size and depth come at the cost of a decreased frame rate and decreased PRF, respectively, producing poor motion imaging. High-frequency, short-wavelength ultrasound is more easily focused and directed to a specific target location. Image resolution increases with short-wavelength sound waves, so ultrasonic frequencies of 2 to 10 MHz are preferred in clinical echocardiography. The shorter the length of the sound pulses, the better the axial resolution of the system. The beam size determines the lateral and elevational resolution. Whereas broad beams produce a “smeared” image of two nearby objects, narrow beams can identify each object individually. (See page 716: Properties of Sound Transmission in Tissue.)
2. Which of the following is an important factor in determining the potential for tissue damage with ultrasonography? A. Frequency B. Wavelength C. Propagation velocity D. Amplitude 2. D. The amplitude of a sound wave represents its peak pressure and is appreciated as loudness. The level of sound energy in an area of tissue is referred to as intensity. The intensity of the sound signal is proportional to the square of the amplitude and is an important factor regarding the potential for tissue damage with ultrasound. The Food and Drug Administration limits the intensity output of cardiac ultrasonography systems to be less than 720 W/cm2 because of concerns of potential tissue injury. Sound waves are also characterized by their frequency (f), or pitch, expressed in cycles per second or Hertz (Hz), and by their wavelength (λ). These attributes significantly impact the depth of penetration of a sound wave in tissue and the image resolution of the ultrasound system. The propagation velocity of sound (v) is determined solely by the medium through which it passes. In soft tissue, the speed of sound is approximately 1540 m/s. (See page 716: Physics of Sound.) 3. The figure below shows an M-mode image across the aortic valve. Which of the following statements regarding M-mode (motion-mode) imaging is FALSE?
A. M-mode imaging displays a series of sequentially collected brightness-mode (B-mode) images. B. M-mode imaging remains the best technique for examining the timing of cardiac events. C. M-mode imaging provides a one-dimensional, single-beam view through the heart. D. M-mode imaging can display shape and lateral motion information about cardiac anatomy. 3. D. Ultrasonic imaging is based on the amplitude and time delay of the reflected signals. By timing the interval between transmission and return of the reflections, the echocardiography system can precisely calculate the distance of a structure from the transducer. Current imaging is based on B-mode technology. With B-mode imaging, the amplitude of the returning echoes from a single pulse determines the display brightness of the representative pixels. M-mode imaging adds temporal information to B-mode imaging by displaying a series of sequentially collected Bmode images. M-mode echocardiography provides a one-dimensional, single-beam view through the heart but updates the B-mode images at a very high rate, providing dynamic real-time imaging. M-mode imaging remains the best technique for examining the timing of cardiac events. Two-dimensional (2-D) echocardiography is a modification of B-mode echocardiography and is the mainstay of the echocardiographic
examination. Instead of repeatedly firing ultrasound pulses in a single direction, the transducer in 2-D echocardiography sequentially directs the ultrasound pulses across a sector of the cardiac anatomy. In this way, 2-D imaging displays a tomographic section of the cardiac anatomy, and unlike M-mode, reveals shape and lateral motion. (See page 716: Instrumentation.) 4. Transesophageal echocardiography (TEE) is the favored approach to intraoperative echocardiography because: A. Compared with transthoracic echocardiography (TTE), TEE offers additional “windows” to view the heart. B. TEE examination is not limited by obesity, emphysema, surgical dressings, or prosthetic valves. C. The TEE probe can be left in situ, providing continuous, realtime hemodynamic information. D. All of the above. 4. D. TEE is the favored approach to intraoperative echocardiography. Compared with TTE, TEE offers additional “windows” to view the heart, often with improved image quality because of the anatomic proximity of the esophagus and heart. In the operating room, TEE is useful because the probe does not interfere with the operative field and can be left in situ, providing continuous, real-time hemodynamic information used to diagnose and manage critical cardiac events. TEE is also useful in situations in which the transthoracic examination is limited by various factors (obesity, emphysema, surgical dressings, prosthetic valves) and for examining cardiac structures that are not well visualized with TTE (e.g., the left atrial appendage). (See page 718: Two-Dimensional and Three-Dimensional Transesophageal Echocardiography Examination.) 5. Which of the following preclude the placement of a transesophageal echocardiography (TEE) probe? A. Esophageal stricture, rings, or webs B. Recent bleeding of esophageal varices C. Zenker's diverticulum D. Recent gastric bypass surgery
E. None of the above 5. E. To maintain the safety profile of TEE, each patient should be evaluated before the procedure for signs, symptoms, and history of esophageal pathology. The most feared complication of TEE is esophageal or gastric perforation. For skilled practitioners, this complication is extremely rare. Patients with extensive esophageal and gastric disease are at highest risk of perforation. Contraindications to TEE probe placement include esophageal stricture, rings, or webs; esophageal masses (especially malignant tumors); recent bleeding of esophageal varices; Zenker's diverticulum; recent radiation to the neck; and recent gastric bypass surgery. In the rare case in which TEE is essential and is the only alternative, placement of the TEE probe can be performed under direct visualization with a combined gastroscopic and echocardiographic examination. (See page 719: Transesophageal Echocardiography Safety.) 6. The midesophageal ascending aorta short-axis (ME AA SAX) view shown on the next page is useful for evaluating:
A. the ascending aorta for dimensions and the presence of dissection flaps B. the pulmonary artery (PA) or the position of a PA catheter or to rule out thrombus C. blood flow in the main PA D. all of the above
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6. D. The ME AA SAX view is obtained by advancing the probe slightly from the upper esophagus until the ascending aorta (AA) is seen and then rotating the multiplane angle from 0 to 45 degrees to obtain a true short axis. This “great vessel view” images the AA in short axis and the main PA with its bifurcation and right pulmonary artery in long axis. The main uses of the ME AA SAX view are to evaluate the AA for dimensions and presence of dissection flaps, evaluate the PA (position of catheter or rule out thrombus), and assess PA blood flow (by aligning the Doppler beam parallel to the blood flow in the main PA). (See page 720: Goals of the Two-Dimensional Examination.) 7. Which of the following monitors is the most accurate indicator of ventricular preload? A. Central venous pressure (CVP) trends B. Pulmonary capillary wedge pressure (PCWP) C. Transesophageal echocardiography (TEE) D. Mixed venous saturation E. Urine output 7. C. The most accurate preload indicator for the left ventricle is the TEE probe because it can assess actual intracardiac chamber size and thus preload. Urine output is another very accurate method of detecting adequacy of left ventricular (LV) preload; however, in healthy people with inadequate LV preload, urine output may be maintained. Conversely, in numerous conditions, urine output is inadequate despite adequate LV preload. CVP trends can be altered by abnormalities within the right ventricle, pulmonary circulation, and left side of the heart. PCWP is accurate only if there are no complicating matters within the lungs (excessive positive end-expiratory pressure), left atrial abnormalities (mitral stenosis), and LV abnormalities (ischemia). Mixed venous O2 saturation is an accurate indicator of the total body O2 supply–demand balance but does not directly measure LV preload; it may be normal despite inadequate LV preload if the heart rate is increased to maintain cardiac output. (See page 719: Monitoring Applications.) 8. Which of the following is the most sensitive indicator of myocardial ischemia?
A. Central venous pressure (CVP) trends B. Pulmonary artery catheter (PAC) C. Transesophageal echocardiography (TEE) D. ST analysis of the electrocardiographic (ECG) tracing in leads II and V5 E. Cardiac output 8. C. Of all the answers, TEE and ST analysis of the ECG are the most accurate of the monitors for detecting myocardial ischemia. The most sensitive and specific of the two is TEE. The regional wall motion abnormalities that occur during ischemia are readily detected by TEE. Abnormal wall thickening and inward motion of the ischemic segment occur within seconds of the segment's becoming ischemic. However, not all wall motion abnormalities are caused by ischemia. When comparing TEE with ECG ST segment analysis, TEE picks up more ischemic episodes. ST analysis is very sensitive for ischemia. Increasing its sensitivity and specificity can be accomplished by placing the leads in the areas most likely to become ischemic. CVP, PAC readings, and cardiac output become abnormal with ischemia; however, they become abnormal late and are not very specific for ischemia. (See page 726: Monitoring Applications.) 9. All of the following statements regarding the transgastric midpapillary short-axis (TG mid-SAX) view shown here are true EXCEPT:
A. It allows the immediate diagnosis of a hypovolemic state or pump failure. B. The left ventricle (LV) is visualized as doughnut shaped in cross-section, and both papillary muscles should be seen. C. It visualizes all the LV walls perfused by each of the three major coronary arteries. D. Doppler assessment of blood flow velocities is most accurate in this view. 9. D. The TG mid-SAX view is obtained by advancing the TEE probe from the midesophageal position into the stomach and anteflexing and then withdrawing it until contact is made with the gastric wall. The LV is visualized as a doughnut shape in cross-section, and both papillary muscles should be seen. Advancement of the probe allows visualization of the LV apex in cross-section. The TG mid-SAX view is unique in that it visualizes all the LV walls perfused by each of the three major coronary arteries. The view is considered to be the most useful one in situations of intraoperative hemodynamic instability because it allows immediate diagnosis of hypovolemic state, pump failure, and coronary ischemia. The primary uses of the TG mid-SAX include assessment of the LV size (enlargement, hypertrophy) and cavity volume and global ventricular systolic function and regional wall motion. Two-dimensional echocardiography captures high-fidelity motion images of cardiac
structures but not blood flow. Blood flow indices such as blood velocities, stroke volume, and pressure gradients are the domain of Doppler echocardiography. (See page 720: Goals of Two-Dimensional Examination.) 10. Doppler assessments are an essential element of the echocardiographic examination. Which of the following statements regarding Doppler measurements is FALSE? A. By monitoring the frequency pattern of reflections from red blood cells (RBCs), Doppler echocardiography can determine the speed, direction, and timing of blood flow. B. The requirement of near parallel orientation to blood flow for Doppler examinations contrasts with the near-perpendicular orientation to cardiac structures preferred for two-dimensional (2-D) imaging. C. When the beam angle divergence is greater than 30 degrees, the Doppler system will markedly overestimate blood velocity. D. Two Doppler techniques, pulsed-wave Doppler (PWD) and continuous-wave Doppler (CWD), are commonly used to evaluate blood flow. 10. C. Unlike 2-D imaging, which relies on the time delay and amplitude of reflected ultrasound, Doppler technologies are based on the change in frequency that occurs when ultrasound interacts with moving objects. Reflections from RBCs are used to determine the blood flow velocity and calculate the hemodynamic parameters. The requirement of nearparallel orientation to blood flow for Doppler examinations contrasts with the near-perpendicular orientation to cardiac structures preferred for 2-D imaging. The Doppler equation Δ f = v × cos&thetas; × 2ft/c describes the relationship between the alteration in ultrasound frequency and blood flow velocity. Conceptually, the equation is simplified by observing that the change in ultrasound frequency is related to just two variables: blood flow velocity and cos &thetas;. When the beam angle divergence is greater than 30 degrees, the value of cos &thetas; decreases rapidly, and the Doppler system markedly underestimates blood velocity. PWD and CWD are commonly used to evaluate blood flow. (See page 728: Doppler Techniques.)
11. Which of the following statements regarding pulsed-wave Doppler (PWD) is FALSE? A. By time gating, PWD offers the ability to sample only signals associated with a specific location, referred to as the sample volume. B. Because PWD data are collected intermittently, the maximal frequency and blood flow velocity that can be accurately measured are limited. C. Aliasing appears on the spectral display as a signal on the other side of the baseline. D. With continuous reception of the PWD signal, the Nyquist limit is not applicable. 11. D. PWD offers the echocardiographer the ability to sample blood flow from a particular location. The PWD system transmits a short burst of ultrasound toward the target and then switches to receive mode to interpret the returning echoes. Because the speed of sound (c) in tissue is constant, the time delay for a signal to reach its target and return to the transducer depends solely on the distance (d) to the target. By time gating, the electronic circuitry of the PW transducer interprets returning echoes only after a predetermined time delay after the transmission of an ultrasound pulse. In this way, only signals associated with a location, referred to as the sample volume, are selected for evaluation. Doppler data are frequently presented as a velocity–time plot known as the spectral display. Because the PWD data are collected intermittently, the maximal frequency and blood flow velocity that can be accurately measured by PWD are limited. The maximal frequency, which equals 50% of the pulse repetition frequency, is known as the Nyquist limit. At blood velocities above the Nyquist limit, analysis of the returning signal becomes ambiguous, with the velocities appearing to be in the opposite direction. The ambiguous signal from frequencies above the Nyquist limit, known as aliasing, appears on the spectral display as a signal on the other side of the baseline, hence the term wraparound. (See page 728: Doppler Techniques.) 12. Given the following data, which of these hemodynamic calculations is CORRECT? The left ventricular outflow tract (LVOT)
time velocity integral (VTI) is 7, the LVOT diameter is 2 cm, the aortic valve (AoV) VTI is 22, and the heart rate is 100 bpm. A. The cardiac output is above 3 L/min. B. The aortic valve area is 1 cm2. C. The LVOT area is about 4 cm2. D. The stroke volume (SV) is about 40 cc. 12. B. Volumetric parameters are calculated using the principle that volumetric flow (Q) equals the blood flow velocity (v) times the crosssectional area (CSA) of the conduit, that is, Q = v × CSA. In effect, the VTI (in centimeters, traced from the spectral Doppler display) represents the distance blood traveled during systole (i.e., stroke distance). By multiplying the VTI by the CSA (cm2) of the conduit through which the blood traveled, the SV (in cm3) is obtained: SV = VTI × CSA. The principle of conservation of mass is the basis of the continuity equation, which is commonly used to measure the AoV area. The continuity equation simply states that the volume of blood passing through one site in the heart (e.g., the LVOT) is equal to the mass or volume of blood passing through another site (e.g., the AoV). Volumetric flow1 = Volumetric flow2 Therefore, CSA1 × VTI1 = CSA2 × VTI2 and CSA1 = CSA2 × VTI2/VTI1 Based on the given data, because the LVOT diameter is 2 cm, the radius is 1 cm. The LVOT cross-sectional area or LVOT CSA is Π × (Radius)2 or approximately 3.14 × 1 cm2. The SV is LVOT VTI × LVOT CSA. This equals 22 cc for the given data. Cardiac output is SV × Heart rate. This equals 2200 cc/min or 2.2 Lpm for the given data. Aortic valve area = LVOT CSA × LVOT VTI/AV VTI. Based on the given data, this works out to exactly 1 cm2. (See page 730: Hemodynamic Assessments.) 13. Given the following data, calculate the estimated pulmonary artery (PA) systolic pressure. The central venous pressure (CVP) is 4 mm Hg. The maximum velocity of the regurgitant tricuspid jet (TR jet) is 3 cm/sec. There is no evidence of a stenotic pulmonary valve. A. 40 mm Hg B. 36 mm Hg
C. 32 mm Hg D. More data are needed. 13. A. Pressure gradients (PGs) are used to estimate intracavitary pressures and to assess conditions such as valvular disease (e.g., aortic stenosis), septal defects, outflow tract obstruction, and major vessel pathology (e.g., coarctation). As blood flows across a narrowed or stenotic orifice, the blood flow velocity increases. The increase in velocities relates to the degree of narrowing. In the clinical situation, the simplified Bernoulli equation describes the relation between the increases in blood flow velocity and the pressure gradient across the narrowed orifice ΔP = 4V2 where ΔP in mm Hg is the pressure gradient across the narrowed orifice and V in meters per second is the maximum velocity across that orifice measured by Doppler. Based on the given data, the pressure gradient across the tricuspid valve should equal 4 × 32 = 36 mm Hg. Because the CVP (approximating the right atrial pressure) is 4 mm Hg, the right ventricular systolic pressure should equal 40 mm Hg (36 + 4). Given no stenosis across the pulmonic orifice, a reasonable estimate of the PA systolic pressure is 40 mm Hg. (See page 732: Intracardiac Pressure Assessment: The Bernoulli Equation.) P 14. Which of the following statements regarding echocardiographic evaluation of left ventricular (LV) systolic function is FALSE? A. Global LV systolic function is influenced by load and contractility alterations. B. Wall motion is the most reliable marker of regional systolic function. C. The most frequently used technique to evaluate global LV function is visual estimation of the fractional area change (FAC). D. Ejection fraction (EF) and stroke volume are not always indicators of intrinsic systolic function. 14. B. Abnormal myocardial wall thickening is a sensitive marker of myocardial ischemia that appears earlier than electrocardiographic and hemodynamic changes. The evaluation of segmental wall motion to detect ischemia is not error free. In addition to being a subjective
assessment, wall motion may be affected by tethering, regional loading conditions, and stunning. Epicardial pacing of the free wall of the right ventricle (as in postbypass period) produces a left bundle block and induces septal wall motion abnormalities. Interobserver reproducibility is better for normally contracting segments than for dysfunctional segments. Because of these issues, wall thickening is a more reliable marker of regional function. EF is the most frequently used estimate of LV systolic function. The evaluation of EF provides prognostic information about mortality and morbidity. EF and stroke volume are affected by factors such as preload, afterload, and heart rate and thus are not always indicators of intrinsic systolic function. Typical clinical scenarios in which EF does not represent LV systolic function include the hypercontractile LV in mitral regurgitation (in which more than half of ED volume may regurgitate inside the left atrium) or the hypocontractile LV in aortic stenosis (in which LV systolic performance is poor despite preserved contractility). The most frequently used technique to evaluate global LV function as well as preload is visual estimation of fractional area change (FAC), often referred to as “eyeball” EF. Although highly subjective, it is practiced widely and is accurate when determined by experienced echocardiographers, especially in patients with normally contracting ventricles. (See page 732: Echocardiographic Evaluation of Systolic Function.) For questions 15 to 20, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 15. Which of the following statements regarding color-flow Doppler (CFD) shown in the image below are TRUE? 1. CFD provides a display of both blood flow and cardiac anatomy by combining two-dimensional (2-D) echocardiography and pulsedwave Doppler (PWD) methods. 2. CFD performs multiple sample volume recordings along each scan line as the beam is swept through the sector. 3. In the most widely accepted color code, red hues indicate flow toward the transducer, and blue hues indicate flow away from the transducer.
4. Aliasing in the color-flow map can be useful to calculate blood flow in mitral valve disease using the proximal isovelocity surface area (PISA) method. 15. E. CFD provides a dramatic display of both blood flow and cardiac anatomy by combining 2-D echocardiography and PWD methods. The PWD used for CFD performs multiple sample volume recordings along each scan line as the beam is swept through the sector. This approach provides flow data at each location in the sector, which can be overlaid on the structural data obtained by 2-D imaging. The Doppler velocity data from each sample volume are color coded and superimposed on top of the grayscale 2-D image. In the most widely accepted color code, red hues indicate flow toward the transducer, and blue hues indicate flow away from the transducer. An important caveat to CFD use in the clinical setting is that CFD is susceptible to alias artifacts. Aliasing in the colorflow map can be useful in calculating blood flow in mitral valve disease using the PISA method. (See page 730: Color-Flow Doppler.) 16. A 67-year-old man is scheduled to have an infra-abdominal aortic aneurysm repaired. The surgeon desires a pulmonary artery catheter (PAC) to be placed in the patient, but the anesthesiologist wants to place a transesophageal echocardiography (TEE) probe. Which of the following statements regarding TEE are TRUE?
1. TEE gives a more accurate estimation of left ventricular (LV) preload than a PAC. 2. Left arterial filling pressures can be calculated by measuring blood flow rates from the pulmonary veins into the left atrium.
3. TEE can accurately identify myocardial ischemia. 4. TEE is free from major complications. 16. A. TEE gives the most accurate estimation of LV preload. It gives a very early indication of myocardial ischemia by its ability to detect wall motion abnormalities. By determining flows across the mitral valve or from the pulmonary veins, LV and left arterial filling pressures can be calculated. TEE is not without its complications. Damage to the esophagus, hemodynamic instability, and dysrhythmias have been reported. (See page 718: Transesophageal Echocardiography: Monitoring Applications.) 17. Which of the following statements regarding the evaluation of left ventricular (LV) diastolic function are TRUE? 1. Diastolic dysfunction is defined as the inability of the LV to fill at normal left atrial (LA) pressures. 2. The transmitral flow curve of an individual with impaired relaxation is represented by a high E wave, low A wave, and shortened deceleration time (DT). 3. Tissue Doppler imaging, which directly measures myocardial velocities, provides a more load-independent methodology of diastolic function assessment. 4. During the “pseudonormal” stage, there is a higher systolic/diastolic (S/D) ratio on the pulmonary vein flow curves. 17. B. Diastolic dysfunction is defined as the inability of the LV to fill at normal LA pressures and is characterized by a decrease in relaxation, LV compliance, or both. The early manifestation of diastolic dysfunction is characterized by impaired relaxation, implying that the rate and duration of decrease in LV pressure after systolic contraction are prolonged, resulting in an inability of the LV to fill adequately during the rapid filling phase. A compensatory increase in filling occurs with atrial contraction. This stage of disease is known as grade I diastolic dysfunction. In more advanced stages of disease (grades II and III of diastolic dysfunction), a decrease in LV compliance ensues. The transmitral flow Doppler (TMF) curve of an individual with abnormal relaxation is represented by a low E, high A, and prolonged DT. Progression of diastolic disease is marked by decreases in LV compliance.
LA pressure increases as a compensatory mechanism to normalize the pressure gradient across the MV. In this scenario, the TMF velocities resemble the normal curve; thus, this stage is known as “pseudonormal.” Because of the high LA pressure, there is less flow from the pulmonary veins during ventricular systole; this generates a lower S wave on the pulmonary vein flow (PVF) curves and thus a lower S/D ratio. One of the important caveats to assessing diastolic function using pulsed-wave Doppler is that the flow patterns depend on pressure gradients and therefore are affected by both preload and afterload. In settings in which the load conditions vary at a fast pace, such as the operating room, changes in TMF or PVF velocities may be difficult to interpret. Tissue Doppler imaging, which directly measures myocardial velocities, provides a more load-independent methodology of diastolic function assessment. (See page 736: Evaluation of Left Ventricular Diastolic Function.) 18. Which of the following statements regarding the echocardiographic evaluation of aortic regurgitation (or incompetence) is FALSE? 1. Associated findings may include dilated aortic root, endocarditis lesions, dilated ascending aorta, calcified aortic valve, or aortic dissection. 2. Vena contracta, the narrowest “neck” of the aortic insufficiency (AI) jet as it traverses the atrioventricular (AV) plane, is usually best appreciated in the midesophagus long-axis (ME AV LAX) view. P 3. Retrograde diastolic flow in the descending and abdominal aorta is sensitive and specific for severe AI. 4. A prolonged pressure half time (PHT) (≥220 ms) is related to severe AI. 18. D. Findings associated with aortic incompetence include a dilated aortic root (Marfan's syndrome), endocarditis lesions, dilated ascending aorta, calcified aortic valve, aortic dissection (may be associated with acute AI), fluttering of the anterior mitral leaflet and restricted diastolic opening of the MV from the AI jet, or a dilated LV in chronic AI. In either
of the ME or the transgastric views of AV, a color-flow Doppler (CFD) sector over the AV and the left ventricular outflow tract (LVOT) demonstrate the presence or absence of the AI regurgitant jet. Vena contracta, the narrowest “neck” of the AI jet as it traverses the AV plane, is usually best appreciated in the ME AV LAX view. The largest diameter of the vena contracta in diastole is selected. The size of the vena contracta is relatively load independent and provides a reliable way to quantitate AI intraoperatively in the presence of fluctuating hemodynamics. The pressure half time (PHT) of the AI jet is recorded in the TG LAX or deep TG LAX views. PHT expresses the pressure equilibration of the diastolic blood pressure (“driving” pressure) and the diastolic left ventricular pressure (“resistance” pressure). A short PHT (69% of the FRC) with oxygen to provide a reservoir for diffusion into the alveolar capillary blood after the onset of apnea. Even under ideal conditions, patients breathing room air (FIO2 = 0.21) will experience oxyhemoglobin desaturation to a level of less than 90% after approximately 2 minutes of apnea. Preoxygenation with 100% O2 via a tight-fitting face mask for 5 minutes in spontaneously breathing patients can furnish up to 10 minutes of oxygen reserve after apnea (in patients without significant cardiopulmonary disease and normal oxygen consumption). A modified vital capacity technique, in which the patient is asked to take eight deep breaths in a 60-second period, shows promise in terms of prolonging the time to desaturation. In obese patients, BiPAP and the head-up position (∼25 degrees) have been advocated to both reach maximal preinduction arterial oxygenation and to delay oxyhemoglobin desaturation. The most common reason for not achieving a maximum alveolar oxygen store during preoxygenation is use of a loose-fitting mask, which allows the entrainment of room air. Leaks as small as 4 mm
(cross-section) may cause significant reductions in the inspired oxygen content. (See page 754: Preoxygenation.) 7. The maximum recommended intracuff pressure for a #4 laryngeal mask airway (LMA) is: A. 20 cm H2O B. 40 cm H2O C. 60 cm H2O D. 80 cm H2O E. none; a volume of air (30 mL) is inserted regardless of pressure 7. C. Before attachment of the anesthesia circuit, the LMA is inflated with the minimum amount of gas to form an effective seal. Although it is difficult to suggest a particular volume of gas to be used, the operator should be accustomed to the feel of the pilot bulb when it is inflated to 60 cm H2O pressure, the maximum suggested seal pressure. (See page 757: Supraglottic Airways.) 8. All of the following statements regarding endotracheal intubation in children are true EXCEPT: A. Elevation of the head on a pillow is not usually necessary. B. Cricoid pressure may be needed to displace an anteriorappearing larynx into view. C. A Macintosh blade is generally more useful because of a larger tongue-to-mouth ratio in children. D. The cricoid cartilage is the narrowest part of the child's airway. E. Hyperextension at the atlanto-occipital joint may cause airway obstruction. 8. C. Because of the relatively larger size of the occiput in children, which produces an “anatomic sniffing position,” elevation of the head (as done in adults) is not needed. On occasion, the thorax may need to be elevated instead. The relatively short neck in children gives the impression of an anterior position of the larynx. Posterior cricoid pressure is often helpful to place the laryngeal inlet into view. A straight
P
blade is more helpful than a curved blade in displacing the stiff, omegashaped, high epiglottis. Because the cricoid cartilage is the narrowest aspect of the airway until children are 6 to 8 years of age, one must be sensitive to resistance to advancement of the endotracheal tube that has easily passed the vocal folds. Hyperextension at the atlanto-occipital joint, as done in adults, may cause airway obstruction in children because of the relative pliability of the trachea. (See page 762: Tracheal Intubation: Use of the Direct Laryngoscope Blade.) 9. Which of the following statements regarding innervation of the airway is TRUE? A. The oropharynx is innervated by branches of the facial, glossopharyngeal, and vagus nerves. B. The oropharynx is innervated by branches of the vagus, glossopharyngeal, and hypoglossal nerves. C. The hypoglossal nerve provides for sensation over the posterior third of the tongue, vallecula, and epiglottis. D. The internal branch of the superior laryngeal nerve provides all sensory innervation below the vocal cords. E. The external branch of the superior laryngeal nerve provides all sensory innervation above the vocal cords. 9. A. The oropharynx is innervated by branches of the vagus, facial, and glossopharyngeal nerves. The glossopharyngeal nerve travels anteriorly along the lateral surface of the pharynx. Its three branches supply sensory innervation to the posterior third of the tongue, the vallecula, the anterior surface of the epiglottis (lingual branch), the walls of the pharynx (pharyngeal branch), and the tonsils (tonsillar branch). The internal branch of the superior laryngeal nerve, which is a branch of the vagus nerve, provides sensory innervation to the base of the tongue, epiglottis, aryepiglottic folds, and arytenoids. The remaining portion of the superior laryngeal nerve, the external branch, supplies motor innervation to the cricothyroid muscle. The hypoglossal nerve provides purely motor innervation to the tongue. (See page 773: Awake Airway Management.)
For questions 10 to 21, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 10. Laryngospasm is commonly caused by: 1. saliva 2. hypercapnia 3. light anesthesia 4. hypoxemia 10. B. Obstruction to mask ventilation may be caused by laryngospasm, which is a reflex closure of the vocal folds. Laryngospasm may occur as a result of foreign body (oral or nasal airway), saliva, blood, or vomitus touching the glottis, or it may occur during a light plane of anesthesia. (See page 756: The Anesthesia Face Mask.) 11. Which of the following statements regarding use of a laryngeal mask airway (LMA) and gastroesophageal reflux is/are TRUE? 1. The LMA fits in the esophageal inlet but does not reliably seal it. 2. There is a high incidence of aspiration when an LMA is used in the presence of a “full stomach.” 3. Aspiration is more common when a bag-valve mask device is used for cardiopulmonary resuscitation than when an LMA is used. 4. If regurgitation is noted when an LMA is in place, it should be removed immediately. 11. B. Although the distal tip of the LMA's mask sits in the esophageal inlet, it does not reliably seal it. A predominant clinical perception is that the LMA does not protect the trachea from regurgitated gastric contents. During cardiopulmonary resuscitation, the incidence of gastroesophageal regurgitation is four times greater with a bag-valve mask than with an LMA. If regurgitated gastric contents are noted in the LMA, maneuvers similar to those applied when using an endotracheal tube should be instituted (i.e., the Trendelenburg position, 100% oxygen, and leaving the LMA in place and using a flexible suction device down the barrel). When populations of patients considered to have a “full
stomach” are studied (in controlled trials, prospective series, or case reports), there is a very low incidence of aspiration noted with elective or emergency LMA use. (See page 758: The Laryngeal Mask Airway Classic.) 12. Which of the following statements regarding the laryngeal mask airway (LMA) is/are TRUE? 1. Positive-pressure ventilation is generally not useful. 2. Gastric inflation is much more likely when positive-pressure ventilation with a pressure of 10 cm H2O is used with an LMA than with an endotracheal tube (ETT). 3. An LMA cannot be used in the lateral position. 4. Tidal volumes of up to 8 mL/kg and airway pressure below 20 cm H2O can be used in positive-pressure ventilation with an LMA. 12. D. Although first introduced for use with spontaneous ventilation, the LMA has shown to be useful when positive-pressure ventilation is either desired or preferred. There is no difference found in gastric inflation with positive pressures below 17 cm H2O when comparing LMA with the ETT. When using the LMA, tidal volumes should be limited to 8 mL/kg and airway pressure to 20 cm H2O because this is the sealing pressure of the device under normal circumstances. Patients' airways have been managed with the LMA in the supine, prone, lateral, oblique, Trendelenburg, and lithotomy positions. (See page 758: The Laryngeal Mask Airway Classic.) 13. Which of the following statements regarding the Sellick maneuver is/are TRUE? 1. It can obliterate the esophageal lumen while maintaining the tracheal opening. 2. It is contraindicated when there is active vomiting. 3. It can be used in conjunction with gentle positive-pressure ventilation. 4. It should be used for rapid sequence induction in patients with laryngeal fractures who have full stomachs.
13. A. Cricoid pressure entails the downward displacement of the cricoid cartilage against the cervical vertebral bodies. In this manner, the lumen of the esophagus is ablated while the completely circular nature of the cricoid cartilage maintains the tracheal lumen. Early cadaveric studies showed that correctly applied cricoid pressure is effective in preventing gastric fluids (80 mm Hg) and maintaining the PaO2 above 95, the ICP below 20 to 25 mm Hg, and the CPP at 50 to 70 mm Hg. Maintaining the CPP above 70 mm Hg (the former standard) is no longer advised because it may be associated with an increased incidence of adult respiratory distress syndrome. The patient is kept at 30 degrees of head elevation, sedation and paralysis are given as necessary, and cerebrospinal fluid is drained through a ventriculostomy catheter, if available. Until about 1995, hyperventilation to a PaCO2 of 25 to 30 mm Hg was a mainstay of therapy of patients with head injury. However, brain ischemia, which is probably the most threatening consequence of head injury, is likely to occur during the first 6 hours after trauma even when the CPP is maintained above the generally recommended 50 to 70 mm Hg. This hypoperfusion seems to be caused largely by increased cerebral vascular resistance, which may be enhanced by hyperventilation. However, some degree of hyperventilation may be necessary for short periods in patients who have severe injuries and elevated ICP that does not respond to normal ventilation and diuretics, although this should not be used during the first 24 hours after injury. (See page 898: Head Injury.) For questions 11 to 22, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are
correct. 11. Which statement(s) regarding neck and chest injuries is/are TRUE? 1. Signs of airway injury include respiratory distress, subcutaneous crepitus, and laryngeal tenderness. 2. First rib fractures are an indication of severe underlying trauma. 3. The most definitive test for pneumothorax in supine patients is computed tomography (CT). 4. After placement of a thoracostomy tube, drainage of 1000 mL of blood and collection of more than 200 mL/hr are indications for thoracotomy. 11. E. Respiratory distress, cyanosis, and stridor are obvious signs of airway injury. Other signs that strongly suggest airway injury are dysphonia, hoarseness, cough, hemoptysis, air bubbling from the wound, subcutaneous crepitus, laryngeal tenderness, pneumothorax, and hemothorax. First rib fractures, because of the high amount of injury required for fracture, indicate severe underlying trauma, particularly to the aorta, subclavian vessels, heart, brain, or spinal cord. Likewise, scapula fractures suggest severe thoracic injury, particularly cardiac and lung injuries. Paradoxically, sternal fractures are usually not associated with serious trauma to the thoracic or abdominal viscera. Upright plain radiographs provide the best opportunity for detection of pleural air. This position, however, may be impossible or contraindicated in some trauma patients. Although chest radiography and an ultrasonography may complement each other, CT is the most definitive radiologic test for detecting pneumothorax. Initial drainage of 1000 mL of blood, or collection of above 200 mL/hr for several hours after thoracostomy, is an indication for thoracotomy. Additional indications are a “white lung” appearance on the anteroposterior chest radiograph, a continuous major air leak from the chest tube, and evidence of pericardial tamponade. (See page 903: Neck Injury, Chest Wall Injury, and Pleural Injury.) 12. Which of the following statements regarding pelvic and extremity injuries is/are TRUE?
1. After pelvic fracture, retroperitoneal hematomas may lead to respiratory difficulty because of pressure on the diaphragm. 2. Angiographic embolization is indicated to treat arterial bleeding after pelvic fracture. 3. Open fractures of the extremities should be repaired within 6 hours to reduce the likelihood of sepsis. 4. Immediate surgery is indicated for extremity compartment syndrome when intracompartmental pressure exceeds 15 cm H2O. 12. A. Pelvic fractures may often result in significant bleeding, but the bleeding tends to be venous in nature and often tamponades itself. Arterial bleeding, in turn, may lead to large retroperitoneal hematomas and thus respiratory difficulty. Thus, angiography and embolization are indicated for treatment of arterial bleeding. Delayed fracture repair is associated with an increased risk of sepsis, pneumonia, deep venous thrombosis, and cerebral complications of fat embolism. Therefore, fixation should occur as soon as possible. In particular, open fractures should be repaired within 6 hours to reduce the risk of sepsis. Compartment syndrome, which is characterized by severe pain in the affected extremity, should be recognized early so emergency fasciotomy can be effective in preventing irreversible muscle and nerve damage. The definitive diagnosis is made by measuring compartment pressures. Pressures exceeding 40 cm H2O are an indication for immediate surgery. (See page 908: Fractures of the Pelvis and Extremity Injuries.) 13. Which statement(s) regarding burns is/are TRUE? 1. Fourth-degree burns involve muscle, fascia, and bone and thus necessitate complete excision, leaving the patient with limited function. 2. Full-thickness burns involving more than 10% of the total body surface area are considered major burns. P 3. Sources of airway compromise after burns include upper airway edema from fluid resuscitation and copious, thick secretions. 4. Because swelling of the airway after thermal injury is only minimal in children, intubation is often not necessary in pediatric
patients. 13. A. The pediatric airway can be greatly compromised by even minimal amounts of swelling because of its small diameter. Prophylactic intubation may often be required in children who are suspected of having an inhalational injury even though they are not yet in respiratory distress. Burns are classified as first, second, third, and fourth degree. First- and second-degree burns are partial thickness, and third- and fourth-degree burns are full thickness. Fourth-degree burns are the most severe and leave the patient with the highest likelihood of decreased function. Major burns include the following: (1) full-thickness burns of more than 10% of the total body surface area; (2) partial-thickness burns of more than 25% of the total body surface area in adults and more than 20% of the total body surface area at extremes of age; (3) burns involving the face, hands, feet, or perineum; (4) inhalational, chemical, or electrical burns; and (5) burns in patients with severe pre-existing medical conditions. In the upper airway, glottic and periglottic edema as well as copious, thick secretions may produce respiratory obstruction; this may be aggravated by fluid resuscitation even in the absence of significant inhalation injury. (See page 908: Burns and Airway Complications.) 14. Which statement(s) regarding carbon monoxide and cyanide poisoning is/are TRUE? 1. Methylene blue is the main treatment for cyanide toxicity. 2. The classic cherry red color of the blood occurs only at carboxyhemoglobin (HbCO) concentrations above 40%. 3. Patients with an HbCO level of above 10% at admission are recommended for hyperbaric O2 therapy. 4. Immediate O2 administration and removal from the toxic environment often obviate the need for specific treatment of cyanide toxicity resulting from smoke inhalation. 14. C. Carbon monoxide interferes with mitochondrial function and produces tissue hypoxia by shifting the hemoglobin dissociation curve to the left. The ultimate effect is impaired release of O2 to tissues. This effect can be offset by high concentrations of inspired O2. The classic
cherry red color of blood occurs at an HbCO concentration of above 40%, but this may be obscured by coexistent hypoxia and cyanosis. Therefore, HbCO concentration by co-oximetry is the most sensitive indicator of carbon monoxide toxicity. The most effective treatment to date for carbon monoxide toxicity is hyperbaric O2 therapy. An HbCO level of 30% or more is an indication for this therapy. Cyanide toxicity may also accompany smoke inhalation in victims of fires within a closed space. Specific treatments for cyanide toxicity include amyl nitrate, sodium nitrite, and thiosulfate. The half-life of cyanide, however, is short (∼1 hour), so removal from the toxic environment and treatment with O2 are often all that are necessary to reduce cyanide levels. (See page 909: Carbon Monoxide Toxicity and Cyanide Toxicity.) 15. Which statement(s) regarding the management of burn injuries is/are TRUE? 1. Fluid flux in burn patients is enhanced by increased intravascular hydrostatic and interstitial osmotic pressures and decreased interstitial hydrostatic pressure. 2. Colloid solutions are preferred for resuscitation during the first day after a burn injury. 3. Fluid resuscitation is essential in the early care of burned patients with injuries of more than 15% of the total body surface area; smaller burns can be managed with replacement at 150% of the calculated maintenance rate. 4. The hematocrit in burn patients should be kept above 30%. 15. B. Fluid flux in burn patients is enhanced by increased intravascular hydrostatic and interstitial osmotic pressures and decreased interstitial hydrostatic pressure. Intravascular volume may be restored with either crystalloid or colloid solutions. Crystalloid solutions are preferred for resuscitation during the first day after a burn injury; leakage of colloids during this phase may increase edema. Fluid resuscitation is essential in the early care of burned patients with injuries of more than 15% of the total body surface area; smaller burns can be managed with replacement at 150% of the calculated maintenance rate and careful monitoring of fluid status. Patients often tolerate a decreased hematocrit after a burn injury. Transfusion is usually not initiated until
the hematocrit is below 15% to 20% in healthy patients, approximately 25% in healthy patients who need extensive procedures, and 30% or more in patients with a history of pre-existing cardiac disease. (See page 910: Fluid Replacement.) 16. Which statement(s) regarding markers for adequate resuscitation is/are TRUE? 1. Sublingual PCO2 is an acceptable marker of organ perfusion. 2. An O2 delivery index of 500 mL/m2/min is an acceptable goal for optimal shock resuscitation. 3. An arterial–end-tidal–arterial CO2 difference above 10 mm Hg predicts mortality after resuscitation in trauma patients. 4. Unrecognized hypoperfusion may allow the passage of luminal micro-organisms across the intestinal wall and may lead to sepsis and multiple organ failure. 16. E. O2 transport variables, base deficit, blood lactate levels, gastric intramucosal pH, and sublingual PCO2 are considered acceptable markers of organ hypoperfusion in apparently resuscitated patients and may be used to set the optimal endpoints of resuscitation. An O2 delivery index of 500 mL/m2/min has been shown to be an acceptable goal for optimal shock resuscitation. A parameter that has been recently used intraoperatively as a guide to resuscitation during emergency surgery for trauma patients is the end-tidal–arterial CO2 difference (PaET)CO2. Values above 10 mm Hg after resuscitation predict mortality. It may also be useful in the decision about when to perform damage control surgery and intraoperatively in guiding resuscitation with fluids, inotropes, and vasopressors. Unrecognized hypoperfusion may lead to splanchnic ischemia with resulting acidosis in the intestinal wall, permitting the passage of luminal micro-organisms into the circulation and release of inflammatory mediators and causing sepsis and multiple organ failure. (See page 914: Organ Perfusion and Oxygen Utilization.) 17. Which statement(s) regarding early postoperative complications in trauma patients is/are FALSE?
1. The wake-up time after a midazolam infusion for postoperative sedation can be up to six times longer than the wake-up time after a propofol infusion. 2. A urine output below 0.5 mL/kg is the most sensitive indicator of acute renal failure. 3. Intra-abdominal pressures above 20 to 25 mm Hg indicate the need for immediate abdominal decompression. 4. In trauma patients, deep venous thrombosis (DVT) usually occurs more than 1 week after the injury. 17. C. Postoperative sedation with midazolam for mechanically ventilated patients can result in mean wake-up times of 660 ± 440 minutes; the wake-up time for a similar group of patients sedated with propofol was 110 ± 50 minutes. Although both drugs are safe and effective, propofol clearly results in a faster wake-up time and earlier ability to extensively examine a patient's neurologic status. Urine output is a relatively insensitive test for diagnosing acute renal failure. More objective data are obtained by calculating free-water clearance or creatinine clearance. A creatinine clearance below 25 mL/min or freewater clearance above 15 mL/hr suggests the likelihood of acute renal failure. Abdominal compartment syndrome results from increased intraabdominal pressure and associated decreased organ perfusion pressure, leading to multiple organ failure and death. A normal intra-abdominal pressure is 3 to 10 mm Hg; values above 20 to 25 mm Hg indicate the need for immediate decompression. Clinically, a tense, distended abdomen should direct the clinician to measure the intravesical pressure via a Foley catheter, which reflects the intra-abdominal pressure. Trauma patients are at extreme risk for DVT. The overall incidence of DVT is approximately 18% in trauma patients. Almost 50% of all cases of pulmonary embolus occur within the first week, suggesting that DVT develops shortly after trauma. (See page 922: Early Postoperative Considerations: Sedation and Analgesia, Acute Renal Failure, Abdominal Compartment Syndrome, and Thromboembolism.) 18. Airway management in the presence of potential cervical spine injury should include which of the following consideration(s)? 1. Associated head injury
2. Manual in-line stabilization of the neck 3. “Clearance” of the cervical spine at the earliest possible time 4. Radiographic studies in comatose patients 18. E. Approximately 2% to 10% of head trauma victims have cervical spine injuries, and 25% to 50% of patients with cervical spine injuries have an associated head injury. In conscious patients, neck pain, tenderness, and extremity paresthesias are strong indicators of spine injury. It is a priori necessary to protect the neck during airway maneuvers in any patient with a possibly unstable cervical spine. Clearance of the neck should be performed at the earliest possible time, not necessarily to facilitate airway management but to minimize the risk of pressure ulceration by the collar. In awake patients with suggestive findings by the NEXUS or Canadian criteria and those who are in a coma or obtunded, the diagnosis of cervical spine injury necessitates the use of radiographic studies in addition to the clinical examination. Stabilization of the head, neck, and torso in neutral position for airway management in patients whose cervical spines are yet to be cleared is best accomplished by manual in-line immobilization. (See page 892: Cervical Spine Injury.) 19. In patients with pulmonary contusions, which of the following statement(s) is/are TRUE? 1. Low tidal volumes, positive end-expiratory pressure (PEEP), and low plateau pressures decrease the likelihood of acute respiratory distress syndrome (ARDS)–related lung injury. 2. Airway pressure release ventilation (APRV) may provide improved V/Q matching. 3. Double-lumen tubes may be used to provide differential lung ventilation. 4. High-frequency jet ventilation (HFJV) may enhance oxygenation in life-threatening hypoxemia. 19. E. In patients with pulmonary contusion, respiratory insufficiency or failure despite adequate analgesia, clinical evidence of severe shock, associated severe head injury or injury requiring surgery, airway obstruction, and significant pre-existing chronic pulmonary disease are
indications for tracheal intubation and mechanical ventilation. PEEP with low tidal volumes (6–8 mL/kg) and low inspiratory alveolar or plateau pressures should be used to decrease the likelihood of ARDS if ventilation is controlled. In intubated, spontaneously breathing patients, airway pressure release ventilation, in which spontaneous breathing is superimposed on mechanical ventilation by intermittent sudden, brief decrease of continuous positive airway pressure, provides improved V/Q matching and systemic blood pressure, lower sedation requirements, greater O2 delivery, and shorter periods of intubation. Patients with severe, unilateral pulmonary contusion unresponsive to these measures may be treated by differential lung ventilation via a double-lumen endobronchial tube. In bilateral severe contusions with life-threatening hypoxemia, HFJV may enhance oxygenation and cardiac function, which may be compromised by concomitant myocardial contusion or ischemia. (See page 894: Thoracic Airway Injuries: Management of Breathing Abnormalities.) 20. During the initial management of shock in trauma patients: 1. normal heart rate and blood pressure indicate adequate tissue perfusion 2. an elevated base deficit may reflect oxygen debt 3. blood lactate levels decline promptly with adequate resuscitation 4. maximal fluid therapy may be delayed until surgical control of bleeding 20. C. Some of the proven markers of organ perfusion may be used during the early management of patients with shock to set the goals of resuscitation. Of these, the base deficit and blood lactate level are the most useful and practical tools during all phases of shock, including the earliest. The base deficit reflects the severity of shock, the oxygen debt, changes in O2 delivery, the adequacy of fluid resuscitation, and the likelihood of multiple organ failure and survival with reasonable accuracy in previously healthy adult and pediatric trauma patients. The normal plasma lactate concentration is 0.5 to 1.5 mmol/L; levels above 5 mmol/L indicate significant lactic acidosis. The half-life of lactate is approximately 3 hours, so the level decreases rather gradually after
correction of the cause. Equating a normal heart rate and systemic blood pressure with normovolemia during initial resuscitation may lead to loss of valuable time for treating underlying occult hypovolemia or hypoperfusion. Bickell et al showed that delaying fluid resuscitation until surgical control of bleeding in victims of penetrating trauma improved survival to hospital discharge and decreased the length of hospital stay. Vigorous fluid therapy increases arterial and venous pressures, dilutes clotting factors and platelets, and decreases blood viscosity, so it may reinitiate bleeding already stopped by a soft thrombus. In contrast, slow infusion of isotonic or hypertonic crystalloids, preferably of packed red blood cells, titrated to lower than normal systemic pressure had beneficial effects on animal survival without tissue injury or organ failure. (See page 895: Management of Shock.) 21. Secondary brain injury (after initial traumatic brain injury) may occur as a result of: 1. hypotension 2. hypoxemia 3. anemia 4. hyperglycemia 21. E. Approximately 40% of deaths from trauma are caused by head injury, and even a moderate brain injury may increase the mortality rate of patients with other injuries. In nonsurvivors, progression of the damaged area beyond the directly injured region (i.e., secondary brain injury) can be demonstrated at autopsy. The primary objective of the early management of patients with brain trauma is to prevent or alleviate the secondary injury process that may follow any complication that decreases the oxygen supply to the brain, including systemic hypotension, hypoxemia, anemia, increased intracranial pressure, acidosis, and possibly hyperglycemia (serum glucose >200 mg dL-1). (See page 898: Management of Injuries: Head Injury.) 22. Which statement(s) regarding hypothermia is/are TRUE? 1. Hypothermia is an independent predictor of mortality after trauma.
2. The risk for hypothermia is higher during trauma surgery than for elective surgery. 3. Rapid rewarming may cause hypotension. 4. Convective surface warming effectively treats serious hypothermia. 22. A. Admission hypothermia, which is present in approximately 50% of trauma patients, is an independent risk factor after major trauma, and the mortality rate increases with decreasing temperature. The intraoperative risk of hypothermia is also higher for trauma victims than for patients undergoing elective surgery. Heat loss increases, especially in patients with spinal cord, extensive soft tissue, and burn injuries and in patients who consumed ethanol before surgery or are undergoing body cavity surgery. Rewarming after hypothermia, especially at a rapid rate, may release accumulated metabolic products into the central circulation, causing further myocardial depression, hypotension, and increased acidosis. Convective warming with forced dry air at 43°C may prevent a temperature decrease in most trauma victims but cannot effectively treat severe hypothermia. Because the low specific heat of air has little heat content to give to the cold trauma patient and often because of the nature of the surgical procedure, only a limited body surface area is exposed to warming. (See page 918: Hypothermia.)
Chapter 37 Epidural and Spinal Anesthesia 1. All of the following statements regarding epidural anesthesia are true EXCEPT: A. It can be used to provide postoperative analgesia. B. It has been shown to decrease some postoperative complications. C. It may improve surgical outcome. D. It has become absolutely indicated as the standard of care for certain procedures. E. It has been shown to reduce intraoperative blood loss. 1. D. There are no absolute indications for spinal or epidural anesthesia. Spinal and epidural anesthesia have been shown to blunt the stress response to surgery, decrease intraoperative blood loss, lower the incidence of postoperative thromboembolic events, and decrease morbidity and mortality in high-risk surgical patients. Also, both spinal and epidural techniques may be used to extend analgesia into the postoperative period and to provide analgesia to nonsurgical patients. (See page 927: Introduction.) 2. All of the following statements are true EXCEPT: A. The epidural space is bounded inferiorly by the intervertebral ligament. B. The interspinous ligament attaches to the ligamentum flavum anteriorly. C. The ligamentum nuchae continues inferiorly as the supraspinous ligament. D. Elastin is the primary component of the ligamentum flavum. E. The ligamentum flavum is thickest in the midline.
2. A. The epidural space is bounded inferiorly by the sacrococcygeal ligament covering the sacral hiatus. The interspinous ligament attaches between the spinous processes and blends anteriorly with the ligamentum flavum. Above T7, the supraspinous ligament continues as the ligamentum nuchae. The ligamentum flavum is a tough, wedgeshaped ligament composed of elastin. The ligamentum flavum is thickest in the midline, measuring 3 to 5 mm at the L2–L3 interspace in adults. (See page 929: Ligaments.) 3. The epidural space: A. terminates cranially at C1 B. communicates with the intervertebral space by way of the paravertebral foramina C. surrounds the vertebral canal D. contains a rich network of veins posteriorly E. becomes discontinuous upon injection of liquid 3. C. The epidural space is the space that lies between the spinal meninges and the sides of the vertebral canal. It is bounded cranially by the foramina magnum. The epidural space is not a closed space but communicates with the paravertebral space by way of the intervertebral foramina. The epidural space is composed of a series of discontinuous compartments that become continuous when the potential space separating the compartments is opened by injection of air or liquid. A rich network of valveless veins courses through the anterior and lateral portions of the epidural space, with few, if any, veins present in the posterior epidural space. (See page 929: Epidural Space.) 4. Which of the following statements regarding spinal needle insertion is TRUE? A. The first significant resistance encountered when advancing a needle using the paramedian approach is the interspinous ligament. B. If bone is repeatedly encountered at the same depth when the needle is advanced, the needle is likely walking down the inferior spinous process.
C. The midline approach is preferred in patients with heavily calcified interspinous ligaments. D. Free flow of cerebrospinal fluid (CSF) after resolution of a paresthesia usually indicates that the needle is in a good position. E. Penetration of the dura mater is more easily detected with a beveled needle. 4. D. If a paresthesia occurs upon insertion of a spinal needle, the practitioner should immediately stop advancing the needle, remove the stylet, and look for CSF at the needle hub. Obtaining CSF after resolution of a paresthesia indicates that the needle encountered a cauda equina nerve root in the subarachnoid space and the needle tip is in a good position. Of course, one should not inject local anesthetic in the presence of a persistent paresthesia. The first significant resistance encountered using the paramedian approach should be the ligamentum flavum because the interspinous ligament is bypassed. If bone is repeatedly encountered at the same depth when the needle is advanced, the needle is likely off the midline and walking along the vertebral lamina. The paramedian approach to the epidural and subarachnoid space is useful in situations in which the patient's anatomy does not favor the midline approach (e.g., the inability to flex the spine or heavily calcified intraspinous ligaments). Penetration of the dura mater produces a subtle “pop” that is most easily detected with pencilpoint needles. (See page 933: Midline Approach.) 5. The epidural test dose: A. if negative, confirms that the catheter is in the epidural space B. must be administered before giving a therapeutic dose C. may be omitted if aspiration of the catheter is negative for blood or cerebrospinal fluid (CSF) D. should have an increased concentration of epinephrine if the patient is taking β -adrenergic blockers E. contains epinephrine, which, if given intravenously, typically produces an immediate increase in heart rate within 10 seconds 5. B. Because of the risk of undetected intravenous or subarachnoid migration of the catheter, additional test doses must be administered
before a therapeutic dose is given through the catheter. Aspiration of the catheter or needle to check for blood or CSF is helpful if positive, but the incidence of false-negative aspirations is too high to rely on this technique alone. The most common test dose is 3 mL of local anesthetic containing 5 μg/mL of epinephrine. Intravascular injection of this dose of epinephrine typically produces an average heart rate increase of 30 bpm between 20 and 40 seconds after the injection. Heart rate increases may not be as evident in some patients taking β -adrenergic blockers. In β -blocked patients, systolic blood pressure increases of 20 mm Hg or more may be a more reliable indicator of intravascular injection. (See page 936: Epidural Test Dose.) 6. Rank the following local anesthetics in order of increasing duration for spinal anesthesia. A. Procaine, mepivacaine, tetracaine B. Lidocaine, mepivacaine, procaine C. Lidocaine, procaine, mepivacaine D. Procaine, bupivacaine, mepivacaine E. Tetracaine, procaine, bupivacaine 6. A. The principal determinant of spinal block duration is the local anesthetic drug used. Procaine is the shortest-acting local anesthetic for subarachnoid use. Lidocaine and mepivacaine are agents of intermediate duration, and bupivacaine and tetracaine are the longest-acting drugs currently available in the United States. (See page 940: Local Anesthetic.) 7. The duration of spinal anesthesia is most prolonged when 100 μg of clonidine is added to which of the following local anesthetics? A. Mepivacaine B. Lidocaine C. Tetracaine D. Procaine E. Bupivacaine
7. C. Tetracaine is the local anesthetic that is most dramatically prolonged by addition of adrenergic agonists. Clonidine prolongs tetracaine spinal block by 50% to 70%, with a larger effect occurring at lumbar dermatomes. (See page 940: Adrenergic Agonists.) 8. Rank the following local anesthetics in order of increasing duration P for epidural anesthesia. A. Ropivacaine, bupivacaine, mepivacaine B. Etidocaine, mepivacaine, ropivacaine C. Chloroprocaine, etidocaine, mepivacaine D. Ropivacaine, chloroprocaine, mepivacaine E. Chloroprocaine, mepivacaine, etidocaine 8. E. Chloroprocaine is the shortest-duration local anesthetic used for epidural anesthesia. Lidocaine and mepivacaine provide blocks of intermediate duration, and bupivacaine, ropivacaine, and etidocaine produce the longest-duration epidural blocks. (See page 940: Duration.) 9. All of the following statements regarding complications associated with epidural and spinal anesthesia are true EXCEPT: A. Use of fluid instead of air for loss of resistance during epidural anesthesia reduces the risk of headache upon accidental meningeal puncture. B. An epidural blood patch immediately relieves postdural puncture headache (PDPH) symptoms in approximately 99% of patients. C. Transient reduction in hearing acuity after spinal anesthesia is more common in female than in male patients. D. Back pain is more common after epidural anesthesia than after spinal anesthesia. E. Neurologic injury occurs in about 0.03% to 0.1% of all central neuraxial blocks. 9. B. An epidural blood patch is effective in relieving symptoms within 1 to 24 hours in 85% to 95% of patients; approximately 90% of patients in whom an initial blood patch has failed do respond to a second blood
patch. The use of fluid instead of air for loss of resistance during attempted epidural anesthesia does not alter the risk of accidental meningeal puncture, but it does markedly decrease the risk that the patient will subsequently develop PDPH. Compared with spinal anesthesia, back pain after epidural anesthesia is more common and lasts longer. It has been demonstrated that a 1- to 3-day transient, mild decrease in hearing acuity is common after spinal anesthesia, with an incidence of roughly 40% and a 3:1 female-to-male predominance. Multiple large studies of spinal and epidural anesthesia report that neurologic injury occurs in approximately 0.03% to 0.1% of all central neuraxial blocks, although the block was not clearly proven to be causative in most of these series. (See page 947: Complications.) 10. All of the following statements regarding spinal or epidural anesthesia and spinal hematoma are true EXCEPT: A. Patients taking nonsteroidal anti-inflammatory drugs (NSAIDs) and receiving mini-dose heparin are not at increased risk. B. Patients treated with enoxaparin are at increased risk. C. Patients most commonly present with numbness or lower extremity weakness. D. Spinal hematoma occurs at an estimated incidence of less than one in 150,000. E. The removal of an epidural or an intrathecal catheter presents nearly as great a risk for spinal hematoma as its insertion. 10. A. Drugs not considered putting patients at increased risk of neuraxial bleeding and spinal hematoma formation when used alone may actually increase the risk when they are combined. This may be the case when mini-dose unfractionated heparin and NSAIDs are used concurrently. Patients receiving fractionated low-molecular-weight heparin (e.g., enoxaparin) are considered to be at increased risk for spinal hematoma. Patients with spinal hematoma most commonly present with numbness or lower extremity weakness. Spinal hematoma is a rare but potentially devastating complication of spinal and epidural anesthesia, with an incidence estimated to be less than one in 150,000. The removal of an epidural or intrathecal catheter places the patient at nearly as great a risk of hematoma as catheter insertion. The timing of
removal and anticoagulation should be coordinated. (See page 950: Complications: Spinal Hematoma.) 11. Structures traversed by a properly placed needle in the subarachnoid space via the midline approach include all the following EXCEPT: A. interspinous ligament B. dura mater C. posterior longitudinal ligament D. supraspinous ligament E. ligamentum flavum 11. C. In the midline, the needle penetrates the skin, subcutaneous tissue, supraspinous ligament (superficial to the spinous processes), interspinous ligament (between the spinous processes), ligamentum flavum, epidural space, dura mater, and arachnoid membrane. The anterior and posterior longitudinal ligaments are anterior to the subarachnoid space, attaching to the anterior and posterior surfaces of the vertebral bodies. (See page 928: Anatomy: Ligaments.) 12. A patient receives a spinal anesthetic with a sensory level of T5. Which of the following is likely to occur? A. The small bowel will be dilated and relaxed. B. Glomerular filtration will be decreased by one third. C. Tidal volume will be reduced by one third. D. The cardioaccelerator nerves will be unaffected. E. Blood pressure will lower predominantly by decreasing venous return. 12. E. Spinal anesthesia to a level that affects the sympathetic nervous system (which originates from the intermediolateral cell column between T1 and L2) causes peripheral vasodilation (venodilation and arterial dilation). Blood pressure decreases as a result of decreased venous return. The cardioaccelerator nerves arise from the T1–T4 dermatomes; they are affected by spinal anesthesia to T5 because the level of sympathetic blockade can be two to six dermatomal levels
higher than the sensory block. Renal blood flow and glomerular filtration rate tend to be maintained during spinal anesthesia unless the mean blood pressure decreases markedly. Spinal anesthesia causes contraction of the intestines and increased peristalsis because of unopposed vagal activity. High thoracic levels of spinal anesthesia have virtually no effect on resting ventilatory mechanics, but they compromise active exhalation. Intercostal paralysis interferes with the patient's ability to cough and clear secretions. (See page 945: Cardiovascular Physiology: Spinal Anesthesia.) 13. Which of the following has the lowest baricity? A. Lidocaine 5% in dextrose 7.5% B. A mixture obtained by mixing equal volumes of tetracaine 1% and water C. Bupivacaine 0.75% in dextrose 8.25% D. A mixture obtained by mixing equal volumes of tetracaine 1% and dextrose 10% E. Procaine 10% 13. B. Solutions of local anesthetic that have dextrose are hyperbaric. When an additive such as dextrose is not added, then density, and hence baricity, depend on the concentration (g%) of local anesthetic. Hence, 0.5% tetracaine has a lower baricity than 10% procaine. (See page 936: Block Height.) 14. At 37°C, the average density of cerebrospinal fluid (CSF) is ________________ g/mL. A. 1.3 B. 1.03 C. 1.003 D. 1.0003 E. 0.03 14. D. The average density of CSF is 1.0003 g/mL at 37°C. (See page 936: Block Height.)
15. Intravenous (IV) injection of a typical epidural test dose of an epinephrine-containing solution causes an average increase in heart rate of ________________ bpm. A. 0 B. 2 C. 6 D. 30 E. 60 15. D. The most common test dose is 3 mL of local anesthetic containing 5 μg/mL of epinephrine (1:200,000). IV injection of this dose of epinephrine typically produces an average heart rate increase of 30 bpm between 20 and 40 seconds after injection. Heart rate increases may not be as evident in some patients taking beta-blockers; systolic blood pressure increases of more than 20 mm Hg may be a more reliable indicator of intravascular injection in these patients. (See page 936: Epidural Test Dose.) 16. Which of the following statements concerning the addition of epinephrine to a local anesthetic solution during spinal anesthesia is TRUE? A. It is more effective at increasing the duration of lidocaine than tetracaine. B. It is important for modulating the systemic blood level of local anesthetic. C. It may inhibit antinociceptive afferents in the spinal cord. D. It is typically administered in a concentration of 10 g/mL. E. It is typically administered in a concentration of 1:200,000. 16. C. Epinephrine is frequently added to local anesthetic solutions to increase the duration of spinal anesthesia. This effect is believed to result, at least in part, from vasoconstriction of spinal cord and dural vessels. This leads to decreased vascular uptake of the local anesthetic. The fact that it is more effective for tetracaine than for lidocaine or bupivacaine may be attributed to the finding that of the three drugs, tetracaine causes the greatest (and bupivacaine the least)
vasoconstriction in spinal cord blood flow. Blood concentrations of local anesthetic during spinal anesthesia are not clinically significant; hence, epinephrine is not important for modulating the systemic levels of local anesthetic. Epinephrine and related agents may cause inhibition of antinociceptive afferents, an effect that is mediated by stimulation of α 2 receptors in the spinal cord. The dose of epinephrine during spinal anesthesia usually is 0.2 to 0.3 mg (0.2–0.3 mL of 1:1000 solution). Lesser concentrations are used during epidural anesthesia, typically 1:200,000 (1 g/200,000 mL or 5 μg/mL). (See page 940: Adrenergic Agonists.) 17. Which of the following statements concerning the choice of local anesthetic solution for epidural use is TRUE? A. Agents of high anesthetic potency and duration of action necessarily have slow onsets. B. Etidocaine is an excellent choice for obstetric use because of wide sensory/motor discrimination. C. Ropivacaine has a time course similar to that of lidocaine. D. Prilocaine has less cardiovascular toxicity than bupivacaine and etidocaine. E. The onset and duration of epidural anesthesia are most closely related to the volume of local anesthetic used. 17. D. Bupivacaine and etidocaine are highly potent, long-duration local anesthetics. The onset of bupivacaine epidural anesthesia is relatively slow (15–20 minutes); the onset of etidocaine is more rapid. Bupivacaine has excellent sensory/motor discrimination; when used in obstetrics as a 0.125% solution, it may provide good sensory analgesia with minimal motor block. Etidocaine has relatively little sensory/motor discrimination and generally induces profound motor block. Prilocaine has less cardiovascular and central nervous system toxicities than lidocaine or bupivacaine, but it may cause methemoglobinemia when given in doses above 600 mg. Ropivacaine has a time course similar to that of bupivacaine. Within limits, the onset and duration of epidural blockade are more closely related to the mass of drug rather than to variations in volume or concentration. (See page 940: Duration.)
P 18. The first function to be lost during the onset of spinal anesthesia is: A. touch B. motor power C. temperature sensation D. vibration E. autonomic activity 18. E. The onset of block is fastest at sympathetic fibers. The level of sympathetic block may extend two to six dermatomes higher than loss of pinprick sensation and four to eight dermatomes higher than motor blockade. (See page 944: Differential Nerve Block.) 19. Which of the following statements concerning a decrease in blood pressure of 30% during spinal anesthesia is TRUE? A. It is primarily the result of arteriolar dilation. B. It should be treated with a modest head-up position to prevent further cephalad spread of the local anesthetic. C. It must be treated aggressively in all patients. D. It may be treated effectively with a venoselective constrictor. E. It indicates that the patient was hypovolemic before induction of spinal anesthesia. 19. D. Hypotension during spinal anesthesia that is below that which blocks cardioaccelerator fibers is primarily caused by venodilation leading to venous pooling and decreased cardiac output as well as decreased systemic vascular resistance resulting from arterial dilation. The amount of hypotension is related to the level of the sympathectomy. Although the cephalad spread of a hyperbaric solution may be limited by placing the patient in a head-up position, this should not be done to treat patients with existing hypotension because it will further decrease venous return. A decrease in blood pressure of 20% to 30% is usually well tolerated, but selected patients with cardiac, renal, or cerebrovascular disease may require treatment. Potential treatments may include
modest head-down position, vasoconstrictors, and fluid administration. (See page 947: Complications of Spinal and Epidural Anesthesia.) 20. All of the following statements about postdural puncture headaches (PDPHs) are true EXCEPT: A. They are frequently unilateral. B. They are improved by recumbency. C. They are usually frontal or occipital. D. They may be accompanied by tinnitus and photophobia. E. They are usually self-limiting. 20. A. PDPHs are classically described as bilateral, in the occipital or frontal regions. They are worsened by the upright position, improved in the supine position, and may be accompanied by tinnitus or photophobia. Nearly all PDPHs resolve over time without invasive therapy; however, an epidural blood patch may be indicated when the symptoms are severe. (See page 947: Postdural Puncture Headache.) 21. Measures to decrease the incidence of postdural puncture headache (PDPH) include all of the following EXCEPT: A. use of a paramedian approach B. use of small-gauge spinal needles C. lowering the glucose concentration of the local anesthetic solution D. maintaining the patient in the supine position for at least 12 hours after surgery E. inserting the spinal needle bevel parallel to the dural fibers 21. D. The incidence of PDPH is increased in young patients, women, and pregnant patients. The paramedian approach results in less CSF leakage and thus decreases the chance for development of PDPH. Smallgauge and closed-tip needles are associated with a lower incidence of PDPH. Interestingly, there appears to be a direct relationship between the glucose concentration in the local anesthetic and the incidence of PDPH. Although bed rest is indicated in the treatment of patients with
PDPH, it does not decrease the likelihood of developing PDPH. (See page 947: Postdural Puncture Headache.) 22. Which of the following statements concerning high spinal anesthesia is TRUE? A. It is less common in parturients. B. It carries a high mortality rate. C. If it occurs, phrenic nerve paralysis is relatively short-lived. D. It is most likely to occur 30 minutes after the induction of spinal anesthesia. E. Apnea is virtually always a consequence of either ventilatory muscle paralysis or sedative medications. 22. C. Excessive spread of spinal anesthesia may occur in any patient, but parturients are most susceptible. It is most likely to occur shortly after induction of spinal anesthesia, but block height may be influenced for as long as 60 minutes after injection. When recognized early and treated with pressor support and ventilation, high spinal anesthesia should be merely an inconvenience, with no mortality. If phrenic nerve paralysis occurs, it usually is short-lived. Respiratory arrest may occur as a result of respiratory muscle paralysis or dysfunction of brainstem respiratory control centers. (See page 948: Total Spinal Anesthesia.) 23. Which of the following vertebrae has the most prominent spinous process? A. C5 B. C2 C. T1 D. T12 E. L5 23. C. The most prominent spinous process is T1. (See page 928: Anatomy: Vertebrae.) For questions 24 to 36, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are
correct. 24. Which of the following statements is/are TRUE? 1. The vertebral canal is formed by two laminae anteriorly. 2. The spinous process for C1 serves as a site for muscle and ligament attachments. 3. Six sacral vertebrae are fused together to form the sacrum. 4. The first cervical vertebra does not have a vertebral body. 24. D. With the exception of C1, the cervical, thoracic, and lumbar vertebrae consist of a body anteriorly, two pedicles that project posteriorly from the body, and two laminae that connect the pedicles. The first cervical vertebra differs from this typical structure in that it does not have a body or a spinous process. The five sacral vertebrae are fused together to form the wedge-shaped sacrum. (See page 928: Vertebrae.) 25. Which of the following statements regarding vertebral anatomy is/are TRUE? 1. The sacral cornu are located on either side of the sacral hiatus. 2. The twelfth thoracic rib can be helpful in identifying the twelfth thoracic vertebrae. 3. A horizontal line at the level of the iliac crests corresponds to the L4–L5 interspace. 4. C5 is the most prominent spinous process encountered upon palpation of the posterior neck. 25. A. The sacral cornu are bony prominences on either side of the sacral hiatus and aid in identifying it. The spine of C7 is the first prominent spinous process encountered while running the hand down the back of the neck. The twelfth thoracic vertebrae can be identified by palpating the twelfth rib and tracing it back to its attachment to T12. A line drawn between the iliac crests crosses the body of L5 or the L4–L5 interspace. (See page 928: Vertebrae.) 26. Which of the following statements is/are FALSE?
1. The subdural space lies between the arachnoid mater and the pia mater. 2. The dura mater fuses with the filum terminale at the level of the second sacral vertebrae. 3. The plica medianis dorsalis is usually the structure responsible for inadequate spread of epidural anesthesia. 4. At birth, the spinal cord ends at about the level of the third lumbar vertebra. 26. B. Distally, the dura mater ends at approximately S2, where it fuses with the filum terminale. At birth, the spinal cord ends at about the level of the third lumbar vertebrae. In adults, the caudal tip of the spinal cord typically lies at the level of the first lumbar vertebrae. The inner surface of the dura mater abuts the arachnoid mater. There is a potential space between these two membranes called the subdural space. The plica medianis dorsalis is thought to be a connective tissue band running from the dura mater to the ligamentum flavum. The plica medianis dorsalis does not appear to be clinically relevant with respect to clinical epidural anesthesia. (See page 929: Dura Mater.) 27. Which of the following statements regarding spinal needles is/are TRUE? 1. The Quinke needle has a cutting edge. 2. The Sprotte needle requires more insertion force than the Greene needle. 3. Use of a stylet in a spinal needle may prevent formation of dermoid tumors in the subarachnoid space. 4. The Whitacre needle has a “pencil-point” tip. 27. E. The Whitacre and Sprotte needles each have a pencil-point tip with a needle hole on the side of the shaft. The Greene and Quinke needles have beveled tips with cutting edges. Pencil-point needles require more force to insert than beveled-tip needles, but they provide a better tactile feel of the various tissues encountered as the needle is inserted. All spinal and epidural needles come with a tight-fitting stylet. The stylet prevents the needle from being plugged with skin or fat and
dragging the skin into the epidural or subarachnoid spaces, where the skin may grow and form dermoid tumors. (See page 932: Needles.) 28. Combined spinal–epidural anesthesia (CSEA): 1. has proven to be a technique without risk or limitation 2. requires an epidural needle with a second lumen for the spinal needle P 3. has recently fallen out of favor as a viable anesthetic option 4. may result in high subarachnoid concentrations of medication administered via the epidural catheter 28. D. CSEA is growing in popularity because it combines the rapidonset, dense block of spinal anesthesia with the flexibility afforded by an epidural catheter. Special epidural needles with a separate lumen to accommodate a spinal needle are available for CSEA. However, the technique is easily performed by first placing a standard epidural needle in the epidural space and then inserting an appropriately sized spinal needle through the shaft of the epidural needle into the subarachnoid space. A potential risk of CSEA is that the meningeal hole made by the spinal needle may allow dangerously high concentrations of subsequently administered epidural drugs to reach the subarachnoid space. (See page 936: Combined Spinal–Epidural Anesthesia.) 29. Transient radicular irritation (TRI): 1. is defined as pain or dysesthesia in the legs or buttocks after spinal anesthesia 2. occurs more frequently in obese patients 3. usually resolves within 72 hours 4. occurs most frequently when bupivacaine is used 29. A. TRI is defined as pain or dysesthesia in the legs or buttocks after spinal anesthesia. All local anesthetics have been shown to cause TRI, although the risk appears to be greater with lidocaine than with other local anesthetics. Additional risk factors for TRI include surgery in the lithotomy position, outpatient status, and obesity. The pain usually
resolves spontaneously within 72 hours. (See page 949: Transient Neurologic Symptoms.) 30. Anatomic features pertinent to the performance of neuraxial blockade include: 1. In adults, the spinal cord ends at L1–L2. 2. The angulation of the spinous processes of the thoracic vertebrae makes a paramedian approach preferable. 3. In adults, the dural sac ends at S2. 4. The largest interspace in the vertebral column is L2–L3. 30. A. The largest interspace in the vertebral column is L5–S1, the site of the Taylor paramedian approach. In adults, the spinal cord ends at L1– L2, and the dural sac ends at S2. A line connecting the iliac crests most likely crosses L4 or the L4–L5 interspace. The angulation of the spinous processes of the thoracic vertebrae complicates a midline approach, making the paramedian approach preferable in this region. (See page 928: Anatomy.) 31. The epidural space contains: 1. cerebrospinal fluid (CSF) 2. blood vessels 3. unsheathed spinal roots 4. adipose tissue 31. C. The epidural space is a potential space that normally is filled with loose connective tissue, fatty tissue, and blood vessels. CSF is in the subarachnoid space. The spinal roots appear to traverse the epidural space, but they maintain a thin sleeve of dura around them. (See page 929: Epidural Space.) 32. Factors that may worsen hypotension during epidural anesthesia include: 1. epinephrine in the local anesthetic solution 2. absorption of local anesthetic from the epidural space 3. hypovolemia
4. use of chloroprocaine 32. E. As with spinal anesthesia, epidural anesthesia has hemodynamic effects secondary to interruption of preganglionic sympathetic vasoconstrictor fibers. In addition, the relatively large doses of local anesthetic used are absorbed rapidly and may cause hypotension because of their negative inotropic and peripheral vasodilating effects. Epinephrine absorbed from the epidural space stimulates β 2-receptors and leads to additional vasodilation and reduced diastolic blood pressure. The agents with more rapid onset, chloroprocaine and etidocaine, tend to produce greater hypotension because of rapid blockade of sympathetic fibers. Alternatively, high plasma concentrations of bupivacaine are more likely to cause myocardial depression. The hypotensive effects of epidural anesthesia are exaggerated in hypovolemic patients. (See page 945: Cardiovascular Physiology.) 33. Important factors that influence the distribution of local anesthetics in the subarachnoid space include the: 1. density of the local anesthetic solution 2. shape of the spinal canal 3. position of the patient 4. site of injection 33. E. Many factors are considered to influence the spread of local anesthetic in cerebrospinal fluid. The most important factors are the density of the local anesthetic solution, site of injection, shape of the spinal canal, and position of the patient (for hyperbaric and hypobaric solutions). (See page 936: Block Height.) 34. Isobaric solutions injected at the L1 level are appropriate for spinal anesthesia for: 1. cesarean section 2. femoropopliteal bypass 3. appendectomy 4. repair of hip fracture
34. C. An isobaric solution tends to remain near the site of injection regardless of patient position (unless the solution is not truly isobaric). An isobaric injection in the lumbar region is appropriate for surgical procedures below the L1 dermatome (e.g., femoropopliteal bypass, repair of hip fracture). However, it is not appropriate for surgery at sites innervated by higher dermatomes. (See page 936: Block Height.) 35. TRUE statement(s) about anatomy include: 1. The ligamentum flavum is thickest in the midline, measuring 3 to 5 mm at the L2–L3 interspace in adults. 2. Midline insertion of an epidural needle is least likely to result in unintended meningeal puncture. 3. In adults, the caudad tip of the spinal cord typically lies at the level of the first lumbar vertebrae. 4. At birth, the spinal cord ends at about the level of the fifth lumber vertebra. 35. A. The ligamentum flavum is thickest in the midline, measuring 3 to 5 mm at the L2–L3 interspace in adults. Midline insertion of an epidural needle is least likely to result in unintended meningeal puncture. In adults, the caudad tip of the spinal cord typically lies at the level of the first lumbar vertebrae. However, in 10% of individuals, the spinal cord may extend to L3. At birth, the spinal cord ends at about the level of the third lumber vertebra. (See page 928: Anatomy.) 36. Spinal cord segments that contain the cell bodies of preganglionic sympathetic neurons include: 1. T4 2. C6 3. T10 4. S1 36. B. The intermediolateral gray matter of the T1–L2 spinal cord segments contains the cell bodies of the preganglionic sympathetic neurons. (See page 931: Spinal Cord.)
Chapter 38 Peripheral Nerve Blockade 1. In comparing ultrasound imaging with neurostimulation, all of the following statements are true EXCEPT: A. It has an improved block success. B. It has a reduced time to onset of blockade. C. It is associated with fewer complications. D. Lower frequencies offer the best spatial resolution at superficial locations. E. Whereas high-impedance structures appear hyperechoic, lowimpedance structures appear hypoechoic. 1. D. Compared with neurostimulation, ultrasound guidance for blocks results in improved block success and completeness, prolonged duration of blocks, and reduction in complications. Whereas higher frequencies offer the best spatial resolution at superficial locations, lower frequencies offer better resolution for deeper locations. High-impedance structures result in a bright (hyperechoic) image, and low-impedance structures appear grey (hypoechoic). (See page 957: Common Techniques: Ultrasound Imaging: Basics of Technique and Equipment.) 2. The highest systemic blood concentration of local anesthesia occurs after which of the following? A. Epidural anesthesia with pinprick level at T6 B. Spinal anesthesia with pinprick level at T4 C. Bier block anesthesia to left upper extremity D. Bilateral intercostal blocks at T6–T12 E. Interscalene block to the right shoulder 2. D. The highest blood level of local anesthetic occurs after multiple intercostal nerve blocks. (See page 960: Avoiding Complications: Local
Anesthetic Drug Selection and Doses.) 3. The absorption of local anesthetic drug and duration of anesthesia are related to all of the following EXCEPT: A. total dose of local anesthetic used B. use of epinephrine C. location of injection D. ester versus amide local anesthetic E. physical properties of the local anesthetic 3. D. The higher the dose of local anesthetic, the greater the amount of drug that is available for local effect. Epinephrine causes local vasoconstriction and therefore decreases the uptake of local anesthetic into the bloodstream. The relative absorption of local anesthetic is greatest after an intercostal nerve block. The physical properties of the local anesthetic influence the absorption of the drug and the body's ability to break down the drug and excrete it. However, there is no difference in the absorption of the drug based on the classification of the local anesthetic as an amide or ester. (See page 961: Local Anesthetic Drug Selection and Doses.) 4. Select the correct order of anesthetic techniques with respect to systemic blood concentration from highest to lowest. A. Spinal anesthesia, caudal block, brachial plexus block, intercostal block B. Intercostal block, spinal anesthesia, brachial plexus block, caudal block C. Intercostal block, caudal block, epidural block, brachial plexus block D. Epidural block, intercostal block, caudal block, spinal block E. Caudal block, intercostal block, brachial plexus block, spinal block 4. C. The highest blood concentration occurs after an intercostal blockade, followed by caudal blockade, epidural blockade, and brachial
plexus blockade. The lowest blood concentration occurs after a spinal blockade. (See page 961: Local Anesthetic Drug Selection and Doses.) 5. All of the following concerning peripheral nerve blockade are true EXCEPT: A. Complaints of a “cramping” or “aching” sensation during injection may indicate intraneural injection. B. Use of a nerve stimulator with a variable amperage output and an insulated needle requires familiarity with anatomy. C. Obtaining a sensory paresthesia is an acceptable technique. D. Aspiration of blood or proximity of nerves to bones may make localization simpler. E. Ultrasound guidance to localize nerves is a simple technique to master. 5. E. The traditional sign of successful localization of a nerve is eliciting a paresthesia. The patient will complain of an “electrical shock”–like sensation in the involved area. Complaints of “cramping” or “aching” sensation during injection is a sign of possible intraneural injection. A greater incidence of residual neuropathy is associated with this technique compared with other techniques. Use of a nerve stimulator for localization of the nerve is an alternative technique. A nerve stimulator with variable amperage allows localization of the nerve without contacting it and may reduce the chance of nerve injury. When a low current is applied to a peripheral nerve, it will produce stimulation of the motor fibers. The closer it is in proximity to the nerve, the less amperage required to elicit the motor response. Familiarity with anatomy and technique is necessary to bring the needle in close proximity to the nerve. Transarterial localization of the brachial plexus is a technique for performing an axillary block. The axillary artery is transfixed, and the needle is passed through the artery. Local anesthetic is deposited on this side of the artery, and the needle is withdrawn until it is brought back through the proximal wall. Additional local anesthetic is deposited there as well. Ultrasound guidance to localize nerves shows promise but requires complex equipment and experience. (See page 957: Common Techniques: Nerve Stimulation and Ultrasound Imaging.)
6. Which of the following statements concerning the trigeminal nerve is FALSE? A. It is a sensory and motor nerve innervating the face. B. Four major branches of the trigeminal nerve exit from the skull. C. The mandibular nerve is the largest branch and is the only one to receive motor fibers. D. Most applications of trigeminal nerve block may be performed by injection of the terminal branches of the nerve. E. The frontal branch bifurcates into the supratrochlear and supraorbital nerves. 6. B. The trigeminal nerve (fifth cranial nerve) is a sensory and motor nerve to the face. Its roots arise from the base of the pons, and it sends sensory branches to the large gasserian ganglion. The three major branches of this nerve are the ophthalmic, maxillary, and mandibular branches. The ophthalmic branch bifurcates to form the supratrochlear and supraorbital nerves. The maxillary branch is the middle branch and is a sensory nerve. The mandibular branch is the third and largest branch and is the only one with motor fibers. Blockade of the gasserian ganglion is used for treatment of disabling trigeminal neuralgia; however, it is very difficult to perform. Blockade of the three terminal branches is relatively simple. (See page 962: Specific Techniques: Head and Neck [Trigeminal Nerve Blocks].) 7. All of the following statements concerning cervical plexus blockade are true EXCEPT: A. The cervical plexus consists solely of nerve fibers from C1 and C2. B. Blockade of the cervical plexus may involve only sensory nerves because of the separation of motor and sensory fibers early in their course. C. Carotid endarterectomy may be performed under cervical plexus blockade. P
D. Blockade of this plexus may provide adequate anesthesia for thyroid surgery. E. Paresthesias are usually not necessary to perform adequate blockade of the cervical plexus. 7. A. The sensory fibers of the neck and posterior neck arise from nerve roots of the C2, C3, and C4 nerves. The sensory fibers separate from the motor fibers early, so isolated sensory blockade is possible. Cervical plexus blockade can be used for surgery on the neck, such as thyroidectomy and carotid endarterectomy. Occasionally, the thyroid gland may need supplemental local anesthesia, and the carotid bifurcation will need infiltration to block reflex hemodynamic changes. Paresthesias are not required to perform this procedure. (See page 962: Specific Techniques: Head and Neck [Cervical Plexus Blocks].) 8. Even when properly performed, cervical plexus blockade may result in all of the following EXCEPT: A. intravascular injection of local anesthetic with rapid onset of seizures B. phrenic nerve paralysis C. recurrent laryngeal nerve blockade D. epidural or subarachnoid anesthesia E. ipsilateral pneumothorax 8. E. Complications from cervical plexus blockade may include intravascular injection into the vertebral artery, epidural or spinal anesthesia if the needle is advanced too far medially, phrenic nerve blockade, recurrent laryngeal nerve blockade, and vagal blockade. Ipsilateral pneumothorax should not occur. (See page 962: Specific Techniques: Head and Neck [Cervical Plexus Blocks].) 9. Interscalene blockade is typically associated with all of the following EXCEPT: A. anesthesia to the shoulder and upper arm B. anesthesia of the ulnar border of the forearm C. anesthesia of the musculocutaneous nerve
D. anesthesia to the radial and median nerves of the upper arm E. possible Horner syndrome by spread to the sympathetic chain 9. B. The interscalene approach to the brachial plexus at the level of C6 provides blockade for operations on the shoulder and upper arm procedures. It frequently spares C8 and T1 fibers and therefore does not provide adequate blockade to the ulnar border of the forearm. Nerve roots for the musculocutaneous, radial, and median nerves are adequately anesthetized. However, if a tourniquet is being used, a subcutaneous ring of anesthetic is required to block the superficial intercostobrachial fibers in the axilla. Horner syndrome may occur by spread of local anesthesia to the sympathetic chain. (See page 968: Upper Extremity: Brachial Plexus Blockade: Interscalene Block.) 10. The interscalene approach to the brachial plexus involves all of the following EXCEPT: A. head positioning so that it is turned to the opposite side B. palpation of the groove between the anterior and middle scalene muscle, which is located by having the patient tense the scalene muscles by raising the head slightly in the sniffing position C. injection of 25 to 30 mL of local anesthetic when using a nerve stimulation technique D. introduction of the needle perpendicular to the skin in all planes so that it is directed medially, cephalad, and slightly anteriorly E. locating the cricoid cartilage 10. D. The patient is placed in the supine position with the head turned to the side opposite that to be blocked. The lateral border of the sternocleidomastoid muscle is identified. By tensing the scalene muscles, the groove between the anterior and middle scalene muscles may be palpated. The level of the cricoid cartilage is marked. A 22gauge, 2.5-cm or less (≤5 cm for ultrasound guidance) needle is introduced through the skin perpendicular to all planes at the level of the cricoid cartilage so that it is directed medially, caudad, and slightly posterior. Approximately 25 to 30 mL of local anesthetic is required for
adequate blockade when a nerve stimulation technique is used. (See page 962: Specific Techniques: Upper Extremity: Brachial Plexus Blockade: Interscalene Block.) For questions 11 to 19, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 11. Complications of the interscalene approach to the brachial plexus may include: 1. puncture of the lung viscera and a pneumothorax 2. injection of local anesthesia into the epidural or subarachnoid space 3. intravascular injection of local anesthesia via the vertebral artery 4. ipsilateral Horner syndrome 11. E. Complications from the interscalene approach to the brachial plexus are pneumothorax (if the needle is directed too inferiorly), spinal or epidural anesthesia (if the needle passes medially and enters the intervertebral foramina), intravascular injection into the vertebral artery (if the needle is too posterior because the artery passes posteriorly at the level of the sixth vertebra to lie in its canal in the transverse process), and ipsilateral Horner syndrome (because of blockade of the sympathetic chain on the anterior vertebral body). Phrenic nerve blockade may occur as well. (See page 962: Specific Techniques: Upper Extremity: Brachial Plexus Blockade: Interscalene Block.) 12. Which of the following statements regarding the axillary approach to the brachial plexus is/are TRUE? 1. It carries the least chance of pneumothorax. 2. The musculocutaneous nerve is easily anesthetized. 3. Septa within the sheath may limit the spread of local anesthetic. 4. Injection at multiple sites in the axilla is not recommended because the axillary artery may be punctured.
12. B. The axillary approach to the brachial plexus carries the least chance of pneumothorax. Fascial septa within the sheath may limit the spread of local anesthetic; therefore, injection of local anesthetic at multiple sites in the axilla is recommended. The musculocutaneous nerve departs from the sheath high in the axilla and may be spared with this technique. (See page 962: Specific Techniques: Brachial Plexus: Axillary Block.) 13. Which of the following statements regarding intravenous regional anesthesia is/are TRUE? 1. The tourniquet should be inflated to 300 mm Hg or 2.5 times the patient's systolic blood pressure. 2. Lidocaine with epinephrine is the most commonly used anesthetic for this procedure. 3. If surgery is completed in 15 minutes, the tourniquet should be deflated and then reinflated to delay the sudden reabsorption of anesthetic. 4. Bupivacaine is the local anesthetic of choice in patients with lidocaine allergy. 13. B. Intravenous regional anesthesia (Bier block) is a form of regional anesthesia in which local anesthetic is injected into the upper extremity distal to an occluding tourniquet. The arm is elevated and exsanguinated by an elastic bandage. The tourniquet is inflated to 300 mm Hg or 2.5 times the patient's blood pressure. The radial pulse must be tested for occlusion. This may be done by palpation or by placement of the pulse oximeter on the extremity. Lidocaine 0.5% is the local anesthetic of choice, but it should not be used with epinephrine. Bupivacaine is not used because of its toxicity. Ideally, surgery lasting up to 1 hour may be performed by this procedure. However, the cannula may be left in place, and medication may be reinjected after 90 minutes. For surgical procedures between 20 and 40 minutes long, the tourniquet should be deflated, reinflated, and then subsequently deflated in an attempt to minimize sudden reabsorption of local anesthetic. (See page 962: Specific Techniques: Upper Extremity: Intravenous Regional Anesthesia.) 14. Intercostal blockade of T6–T12 results in which of the following?
1. It provides analgesia and motor relaxation for upper abdominal procedures. 2. It is useful in reducing pain associated with chest tube insertion and percutaneous biliary drainage procedures. 3. It has the potential for local anesthesia toxicity, especially if performed bilaterally. 4. There is a high incidence of pneumothorax even when the anesthetic is performed by an experienced individual. 14. A. Intercostal blockade may provide both motor and sensory anesthesia of the abdomen and chest. This technique is also useful for reducing pain from chest tube insertion and percutaneous biliary drainage. It is advantageous over spinal or epidural blockade because there is no accompanying sympathetic blockade. Intercostal blockade results in the highest blood concentration of local anesthetic and therefore has the greatest likelihood of toxicity from local anesthetic. The incidence of pneumothorax is rare in experienced hands. (See page 962: Specific Technique: Trunk: Intercostal Nerve Blockade.) 15. Which of the following statements regarding ilioinguinal/iliohypogastric nerve block is/are TRUE? 1. Anesthesia of the iliohypogastric nerve and ilioinguinal nerve is adequate for hernia repair. 2. The nerve roots from T12, L1, and L2 provide fibers to these two nerves. 3. The anteroinferior iliac spine provides the landmark for location of these two nerves. 4. Hematoma formation is a rare complication of this nerve block. 15. D. Ilioinguinal/iliohypogastric nerve blockade provides sensory anesthesia to the lower portion of the abdomen and groin. It is used for anesthesia for hernia repair, but blockade of these two nerves alone is inadequate for hernia repair. Subcutaneous infiltration is needed as well. These two nerves are easily located because of their anatomic relationship to the anterosuperior iliac spine. Nerve roots from L1 and sometimes T12 provide fibers to these two nerves. Hematoma formation
is a rare complication of this block. (See page 962: Specific Techniques: Trunk: Inguinal Nerve Block.) 16. Which of the following statements regarding penile nerve block is/are TRUE? 1. Penile blockade is used for surgical procedures of the glans and shaft of the penis. 2. The penile branches of the pudendal nerve are targeted. 3. A ring block is typically performed. 4. Lidocaine with epinephrine is typically used. 16. A. Penile block is used in surgical procedures involving the glans and the shaft of the penis. The penile branches of the pudendal nerve (S2– S4) are blocked by a circumferential infiltration of the root of the penis (ring block). To avoid compromising penile circulation, epinephrinecontaining solutions should not be used. (See page 962: Specific Techniques: Penile Block.) 17. Which of the following statements regarding blocks of the terminal nerves of the lumbar plexus is/are TRUE? 1. When using a nerve stimulation technique for the lateral femoral cutaneous nerve block, the primary endpoint is paresthesia over the lateral leg thigh with a current of 0.5 to 0.6 mA. 2. An obturator nerve block may be used to prevent obturator reflex during transurethral bladder tumor resections. P 3. A lateral femoral cutaneous nerve block may be used to prevent adductor spasm in patients with multiple sclerosis. 4. A lateral femoral cutaneous nerve block may be used as a diagnostic tool to identify cases of meralgia paresthetica. 17. E. Blockade of the lateral femoral cutaneous nerve may be used as a diagnostic tool to identify cases of meralgia paresthetica. An obturator nerve block aids in preventing the obturator reflex during transurethral bladder tumor resections and for adductor spasms (seen in patients with multiple sclerosis). When using nerve stimulation technique for blockade
of the lateral femoral cutaneous nerve, the primary endpoint is paresthesia of the lateral thigh with a current of approximately 0.5 to 0.6 mA. (See page 962: Specific Techniques: Lower Extremity: Separate Blocks of the Terminal Nerves of the Lumbar Plexus.) 18. Which of the following statements regarding sciatic nerve block is/are TRUE? 1. When used with a saphenous nerve block, a sciatic nerve block may produce adequate anesthesia to the sole of the foot and the lower leg. 2. The sciatic nerve is located deep within the gluteal region, making it difficult to locate. 3. The anterior sciatic nerve block is ideal for patients who cannot be positioned laterally. 4. In the gluteal region, the sciatic nerve is located lateral to the ischial spine and superficial to the ischial bone. 18. E. When used with a saphenous nerve block, a sciatic nerve block may produce adequate anesthesia to the sole of the foot and the lower leg. The sciatic nerve is difficult to locate because of its deep location. With the aid of ultrasound-guided blockade, the identification of various anatomic landmarks may help identify its location. In the gluteal region, the sciatic nerve is seen on ultrasonography lateral to the ischial spine and superficial the ischial bone. For the anterior sciatic nerve block, the patient is positioned supine with the selected leg to be blocked externally rotated, making this block ideal for patients who cannot be positioned laterally. (See page 962: Specific Techniques: Lower Extremity: Sciatic Nerve Blockade using Posterior, Anterior, and Posterior Popliteal Approaches.) 19. Which of the following statements regarding an ankle block is/are TRUE? 1. The three main peripheral nerves need to be blocked. 2. The deep peroneal nerve is located in the deep plane of the anterior tibial artery. 3. The sural nerve is the major sensory nerve to the sole of the foot.
4. The deep peroneal nerve may be located by palpating the tendon of the extensor hallucis longus. 19. C. Five peripheral nerves are anesthetized for an ankle block: the posterior tibial, sural, saphenous, deep peroneal, and superficial peroneal nerves. The posterior tibial nerve is the major nerve to the sole of the foot and is located just posterior to the posterior tibial artery. The sural nerve also innervates the sole of the foot. The saphenous nerve, which is located medially, innervates the anterior surface of the foot. The deep peroneal nerve is located in the deep plane of the anterior tibial artery and may be located by identifying the anterior tibial artery or the tendon of the extensor hallucis longus. The superficial peroneal nerve is located along the skin crease between the anterior tibial artery and the lateral malleolus. (See page 962: Specific Techniques: Lower Extremity: Ankle Blockade.)
Chapter 39 Anesthesia for Neurosurgery 1. Considering cerebrospinal fluid (CSF), which statement is TRUE? A. Normal volume is 250 mL, but four times this amount is produced each day. B. Normal volume is 150 mL, but three times this amount is produced each day. C. Normal volume is 100 mL, but four times this amount is produced each day. D. Normal volume is 50 mL, but three times this amount is produced each day. E. Normal volume is 250 mL, but two times this amount is produced each day. 1. B. Although CSF volume is approximately 150 mL, more than three times this amount is produced in a 24-hour period. (See page 1006: Neurophysiology.) 2. Which of the following statements regarding intracranial pressure (ICP) is TRUE? A. ICP fluctuates significantly in normal states. B. ICP is not changed with changes in cerebrospinal fluid (CSF) volume. C. ICP never changes quickly, always gradually reaching new states of equilibrium. D. ICP is dependent on the volume of intracranial blood, brain tissue, and CSF. E. ICP is increased with any small increase in intracranial volume. 2. D. Intracranial pressure (ICP) is low except in pathologic states. The Monroe-Kellie doctrine states that in the setting of a nondistensible
cranial vault, the volume of blood, CSF, and brain tissue must be in equilibrium. An increase in one of these three elements or the addition of a space-occupying lesion can be accommodated initially through displacement of CSF into the thecal sac, but only to a small extent. A further increase, as with significant cerebral edema or accumulation of an extradural hematoma, quickly leads to a marked increase in ICP because of the low intracranial compliance. (See page 1006: Neurophysiology.) 3. Which of the following statements regarding autoregulation of cerebral blood flow (CBF) is FALSE? A. Autoregulation leads to constant CBF over a range of mean arterial pressures (MAPs). B. Autoregulation maintains constant CBF between MAPs of approximately 60 to 150 mm Hg. C. At the low end of the autoregulation plateau, the cerebrovascular resistance (CVR) is at a maximum. D. Cerebral perfusion pressure (CPP) is dependent on MAP and intracranial pressure (ICP). E. CBF is maintained by adjusting CVR in response to changes in CPP. 3. C. CBF remains approximately constant despite modest swings in arterial blood pressure. The mechanism by which CBF is maintained, originally described by Lassen, is called autoregulation of CBF. As CPP, defined as the difference of MAP and ICP, changes, CVR adjusts to maintain stable flow. Although this range is frequently quoted as a mean arterial pressure range of 60 to 150 mm Hg, there is significant variability between individuals, and these numbers are only approximate. At the low end of the plateau, CVR is at a minimum, and any further decrease in CPP compromise CBF. At the high end of the plateau, CVR is at a maximum, and any further increase in CPP result in hyperemia. (See page 1006: Neurophysiology.) 4. Which of the following statements regarding the effects of anesthetics on cerebral blood flow is TRUE?
A. Inhalation anesthetics cause cerebral vasodilatation in a dosedependent manner. B. Inhalation anesthetics have no effect on cerebral metabolic rate (CMR). C. Thiopental causes increased cerebral blood flow (CBF) and decreased CMR. D. Propofol causes vasoconstriction and increased CMR. E. Ketamine decreases CBF and decreases CMR. 4. A. Inhalation anesthetics tend to cause vasodilation in a dose-related manner. Higher doses result in dominance of the vasodilatory effect and an increase in CBF. They also decrease cerebral metabolism. Intravenous agents, including thiopental and propofol, cause vasoconstriction coupled with a reduction in metabolism. Ketamine, on the other hand, increases flow and metabolism. (See page 1008: Anesthetic Influences.) 5. Which of the following statements regarding the use of hyperventilation to provide brain relaxation is TRUE? A. Hyperventilation is recommended in all patients with traumatic brain injury (TBI). B. Hyperventilation should be continued for 48 hours. C. Hyperventilation is helpful for ischemia because it decreases cerebral blood flow (CBF). D. Hyperventilation is always contraindicated in patients with TBI. E. Hyperventilation should be used for brief periods to manage acute increases in intracranial pressure (ICP). 5. E. Hypocapnic cerebral vasoconstriction provides anesthesiologists with a powerful tool for manipulating CBF. Hyperventilation is routinely used to provide brain relaxation and optimize surgical conditions. But because hyperventilation decreases CBF, it has the theoretical potential for causing or exacerbating cerebral ischemia. Clinically, it has been associated with harm only in the early period of TBI, but it is still recommended to be avoided in all patients with TBI except when necessary for a brief period to manage acute increases in ICP. (See page 1017: Ventilation Management.)
6. Which of the following statements regarding venous air embolism (VAE) is TRUE? A. The sitting position carries little risk of VAE. B. A multi-orifice catheter placed in the superior vena cava is optimal. C. The presence of a patent foramen ovale (PFO) increases the risk of paradoxical emboli. D. Precordial Doppler has not been shown to help detect VAE. E. Patient position should not be changed when treating a VAE. 6. C. For neurosurgery, the sitting position confers the greatest risk for VAE. A Doppler device should be placed on the chest, end-tidal CO2 should be monitored, and plans should be made for treating a VAE if it occurs. A multi-orifice catheter can be placed in the right atrium to evacuate air. Its location can be confirmed either electrocardiographically or with echocardiography. The presence of a PFO increases the risk of paradoxical embolism. (See page 1019: Surgery for Intracranial Tumors.) 7. All of the following complications may occur in patients with aneurysmal subarachnoid hemorrhage EXCEPT: A. Cardiac dysfunction B. Neurogenic pulmonary edema C. Cardiogenic pulmonary edema D. Hydrocephalus E. Secondary hyperthyroidism 7. E. Patients with aneurysmal subarachnoid hemorrhage are at risk for numerous complications that may affect the anesthetic plan. These include cardiac dysfunction, neurogenic or cardiogenic pulmonary edema, hydrocephalus, and further hemorrhage from the aneurysm. (See page 1020: Cerebral Aneurysm Surgery and Endovascular Treatment.) 8. Which of the following statements regarding blood pressure during carotid surgery is true?
P
A. It should be maintained 20% below baseline throughout surgery. B. It should be maintained as close to baseline as possible throughout surgery. C. It should be maintained as close to baseline as possible except during carotid cross-clamping, when it should be increased 20%. D. It should be maintained 20% below baseline except during carotid cross-clamping, when it should be increased to 20% above baseline. E. It should be maintained 20% above baseline throughout surgery. 8. B. Blood pressure should be maintained as close to baseline as possible throughout carotid surgery. Without evidence to support it, some advocate increasing the blood pressure during carotid crossclamping to improve flow through collateral vessels. This practice presupposes that collateralization is marginal and will be helped by the elevation in pressure. Although collateral flow may be marginal, it may also be absent or entirely adequate. In the latter two situations, elevation in blood pressure, through the use of phenylephrine, will only increase myocardial oxygen demand. (See page 1021: Carotid Surgery.) 9. Which of the following is NOT an indication for endotracheal intubation in a patient with traumatic brain injury (TBI)? A. Decreased level of consciousness B. Hypertension C. Increased risk of aspiration D. Hypoxemia E. Need for sedation during diagnostic studies 9. B. If the patient's trachea is not intubated, immediate attention should focus on assessing the airway and making preparations for intubation. Patients with TBI usually have several indications for intubation, including a decreased level of consciousness, increased risk of aspiration, and concern for hypoxemia and hypercarbia. Sometimes these patients must be tracheally intubated and sedated simply to allow further diagnostic studies. (See page 1022: Overview of Traumatic Brain Injury.)
10. The Cushing's response to elevated intracranial pressure (ICP) includes: A. hypertension and bradycardia B. hypotension and tachycardia C. hypertension and tachycardia D. hypotension and bradycardia E. vasodilation and prolonged QRS 10. A. Patients may demonstrate the Cushing's response of hypertension and bradycardia, which signifies brainstem compression from increased ICP. (See page 1025: Emergent Surgery: Neurosurgical.) 11. Cauda equina syndrome is defined by which symptoms? A. Back pain extending to the lower extremities B. Loss of pain and temperature sensation with sparing of proprioception in the lower extremities C. Loss of motor and touch sensation ipsilateral to the lesion and urinary retention D. Perineal anesthesia, urinary retention, and lower extremity weakness E. Loss of motor sensation in the lower extremities with no sensory deficit 11. D. Cauda equina syndrome is the result of injury below the level of the conus, or caudal end of the spinal cord, typically below L2. Compression of the cauda equina results in perineal anesthesia, urinary retention, fecal incontinence, and lower extremity weakness. (See page 1026: Spinal Cord Injury.) For questions 12 to 26, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 12. Which of the following statements regarding electroencephalography (EEG) is/are TRUE?
1. Brain ischemia disrupts the EEG but not in a predictable pattern. 2. Brain ischemia may lead to EEG silence. 3. It is easy to differentiate ischemia from anesthetic effects on EEG. 4. EEG asymmetry between the right and left sides of the brain is a useful tool. 12. C. A progressive reduction in cerebral blood flow produces a reliable pattern change in EEG, and the eventual progression to EEG silence. The monitor is therefore useful when surgical procedures jeopardize the perfusion of the brain, such as during cross-clamping of the carotid artery during carotid endarte-rectomy. EEG is particularly useful in this setting because the spectral analysis on the at-risk side can be compared in real time with the unaffected side, facilitating detection of ischemia by the resultant asymmetry of EEG. The changes in the EEG spectrum seen with ischemia may occur as a result of other influences, however. Intravenous anesthetic agents such as propofol and thiopental, as well as inhaled agents such as isoflurane, cause a similar change in a doserelated manner, with eventual progression to a drug-induced isoelectric EEG. (See page 1009: Electrocardiography.) 13. Which of the following statements regarding evoked potentials is/are TRUE? 1. Inhalation agents disrupt evoked potentials more than intravenous (IV) anesthetics. 2. Brainstem auditory evoked potentials (BAEPs) can be recorded under any anesthetic. 3. No muscular relaxation can be used when monitoring motor evoked potentials (MEPs). 4. Total IV anesthesia is not recommended when monitoring MEPs. 13. A. Inhalation agents, including nitrous oxide, generally have more depressant effects on evoked potential monitoring than IV agents. Whereas cortical evoked potentials with long latency involving multiple synapses are exquisitely sensitive to the influence of anesthetic, shortlatency brainstem and spinal components are resistant to anesthetic
influence. Thus, BAEPs can be recorded under any anesthetic technique. Monitoring of MEPs in general precludes the use of muscle relaxant, although use of a short-acting neuromuscular blocking agent for the purpose of tracheal intubation is not contraindicated if its effect wears off before monitoring and surgery begins. MEP is exquisitely sensitive to the depressant effects of inhalation anesthetics, including nitrous oxide. Although it can be recorded with low-dose agents, the signals are so severely attenuated that this practice is generally not advisable. Total IV anesthesia without nitrous oxide is the ideal anesthetic technique for MEP monitoring. (See page 1011: Influence of Anesthetic Technique.) 14. Which of the following statements concerning intracranial pressure (ICP) monitoring is/are TRUE? 1. ICP provides a measurement of cerebral blood flow (CBF). 2. Ideally, ICP is kept below 30 mm Hg. 3. Patient position has no effect on ICP. 4. It is possible to drain cerebrospinal fluid (CSF) to lower ICP. 14. D. Although monitoring ICP does not provide direct information about CBF, it allows one to calculate CPP, which must be in an appropriate range for CBF to be adequate. When ICP is high and CPP is low, interventions can target either ICP or mean arterial pressure to restore a favorable balance of the two. Ideally, ICP should be maintained below 20 mm Hg. Interventions to lower ICP include suppression of cerebral metabolic activity, positional changes to decrease cerebral venous blood volume, drainage of CSF, removal of brain water with osmotic agents such as mannitol, and if absolutely essential, mild to moderate hyperventilation to further decrease cerebral blood volume. (See page 1012: Intracranial Pressure Monitoring.) 15. Which of the following statements regarding profound hypothermia is/are TRUE? 1. Profound hypothermia has well-known cerebroprotective effects. 2. Cardiopulmonary bypass is necessary when using profound hypothermia.
3. Hypothermia-induced coagulopathy is a concern when using profound hypothermia. 4. When core temperature is below 25°C, circulatory arrest is tolerated for 30 minutes. 15. A. Profound hypothermia is well known for its neuroprotective effects. When core body temperature is below 20°C, circulatory arrest of less than 30 minutes appears to be well tolerated. The practical constraints against using deep hypothermia in settings in which cerebral ischemia is anticipated are numerous. Foremost is the need for cardiopulmonary bypass during the cooling and warming portion of the procedure. Hypothermia-induced coagulopathy is another concern during surgical procedures in cold patients. (See page 1015: Hypothermia.) 16. Which of the following statements regarding hypertension accompanying high intracranial pressure (ICP) are TRUE? 1. Hypertension is a desirable finding because it shows that the patient has an intact stress response. 2. Hypertension may lead to brainstem herniation. 3. Hypertension has been shown to have no effect on the bleeding from a cerebral aneurysm. 4. Hypertension may lead to worsening ICP. 16. C. Hypertension is poorly tolerated by patients after aneurysmal subarachnoid hemorrhage because systolic hypertension is thought to be a cause of recurrent hemorrhage from the aneurysm. Additionally, hypertension may worsen elevated ICP and possibly lead to herniation of cranial contents into the foramen magnum. (See page 1017: Induction and Airway Management.) 17. Succinylcholine (Sch) is contraindicated in all of the following situations EXCEPT: 1. a patient with myelopathy 2. a patient with L4–L5 cord transaction 5 years previously 3. a patient with a stroke 72 hours ago 4. a patient with a stroke 24 hours ago
17. A. Many neurosurgical and spine surgery patients have conditions in which Sch is contraindicated. Muscle denervation from stroke, myelopathy, and spinal cord injury result in upregulation of acetylcholine receptor isoforms across the muscle belly. This upregulation leads to massive release of potassium with use of Sch. It takes 48 hours for this upregulation to occur, so Sch may be used in the first 2 days after the denervation. (See page 1017: Induction and Airway Management.) P 18. Which of the following is/are contraindications for extubation in a neurosurgical patient? 1. Prolonged prone surgery 2. Facial edema and no cuff leak 3. Rales and low oxygen saturation 4. Massive transfusion and no cuff leak 18. E. For extensive spine surgeries in the prone position, significant dependent edema frequently occurs. Although the predictive value of an air leak from around the endotracheal tube cuff is poor in general, the combination of pronounced facial edema and an absent cuff leak after prone surgery should make one suspicious for upper airway edema. Delaying extubation of the trachea under these circumstances is appropriate. Other factors that may delay extubation in these patients include the development of pulmonary edema and hypoxemia from fluid administration, as well as persistent hemodynamic instability. (See page 1018: Emergence.) 19. Which of the following statements regarding endovascular treatment of cerebral aneurysms is/are TRUE? 1. It is a minimally invasive surgery. 2. It typically requires general anesthesia. 3. It may cause severe complications. 4. It is often performed in the cardiac surgery room in case cardiopulmonary bypass is necessary.
19. A. In contrast to aneurysm surgery, endovascular treatment of aneurysms is a minimally invasive procedure performed in the interventional radiology suite. Despite the less invasive nature of this procedure, it can have equally severe complications as surgery, including further hemorrhage, stroke, and vessel dissection. Although the procedure is not particularly stimulating, the general anesthetic needs to be performed with great care. (See page 1009: Electroencephalography.) 20. Which of the following is/are relative contraindications to an “awake” craniotomy? 1. Tumor resection surgery 2. Severe anemia 3. Multiple opioid allergies 4. Difficult airway 20. D. Frequently, the decision to perform a procedure “awake” has been made by the neurosurgeon before the patient meets the anesthesiologist. Typically, these surgeries are for tumors adjacent to the eloquent cortex or for resection of an epileptic focus. It is the role of the anesthesiologist to determine whether the patient is an appropriate candidate for an “awake” procedure. Although patients with difficult airways, obstructive sleep apnea, or orthopnea may present relative contraindications to an “awake” craniotomy, patients with severe anxiety, claustrophobia, or other psychiatric disorders may be particularly inappropriate for this type of procedure. (See page 1021: Epilepsy Surgery and the “Awake” Craniotomy.) 21. Which of the following statements regarding hypertonic saline to manage elevated intracranial pressure (ICP) is/are TRUE? 1. It must be used before attempting ICP control with mannitol. 2. It has never been compared with mannitol for efficacy in controlling ICP. 3. It may cause significant electrolyte disturbances. 4. Unlike mannitol, it does not cause a brisk diuresis.
21. D. Both hypertonic saline (HS) and HS-Dextran have been used to manage patients with elevated ICP, primarily in the setting of intracranial hypertension refractory to mannitol therapy. Because the blood–brain barrier reflection coefficient to sodium ions is approximately 1, HS establishes a gradient that facilitates the movement of water from the brain into the intravascular space. A 2005 study indicated that HS may be more effective in controlling ICP than mannitol. In addition to efficacy, the proposed benefit of HS is lack of severe electrolyte disturbance, which is common with mannitol. The brisk diuresis seen with mannitol is absent from HS therapy. (See page 1022: Overview of Traumatic Brain Injury.) 22. Risk factors for postdecompressive hypotension include all the following EXCEPT: 1. low Glasgow Coma Scale (GCS) score 2. midline shift of the brain on computed tomography (CT) 3. bilateral dilated pupils 4. use of inhalation anesthetics 22. B. Profound hypotension may occur after anesthesia induction, or more likely, after craniectomy when the intrinsic stimulus for blood pressure elevation diminishes. Risk factors for postdecompressive hypotension include low GCS score, absence of basal cisterns on CT, and bilateral dilated pupils. (See page 1025: Emergent Surgery: Neurosurgical.) 23. Spinal column damage may cause spinal cord ischemia through which of the following mechanisms? 1. Hemorrhage 2. Compression 3. Vasospasm 4. Emboli 23. A. Damage to the spinal column may occur without injury to the spinal cord or may cause spinal cord injury through various insults, including compression, hemorrhage, and vasospasm, all of which result
in spinal cord ischemia and infarction. (See page 1026: Spinal Cord Injury.) 24. Which of the following statements regarding urgent intubation of a patient with a spinal cord injury is/are TRUE? 1. Never assume that a patient has a cervical spine injury until there is radiologic evidence. 2. Rapid sequence induction is only rarely indicated. 3. Assessment of neck mobility is important before induction. 4. Manual in-line stabilization is appropriate. 24. D. Cervical spine injury should be presumed in any trauma patient requiring intubation before complete physical and radiographic evaluation. Intubation should proceed with little movement of the cervical spine. A rapid sequence induction with cricoid pressure and manual in-line stabilization is appropriate unless a difficult airway is anticipated. (See page 1027: Urgent Airway Management.) 25. Autonomic hyperreflexia is characterized by: 1. tachycardia 2. its occurrence in patients with spinal cord lesions above T7 3. intense vasoconstriction above the level of the lesion 4. intense vasoconstriction below the level of the lesion 25. C. Patients with chronic spinal cord lesion above T7 may develop autonomic reflexia when stimulated below the site of the lesion. This is a condition characterized by intense vasoconstriction below the site of the lesion accompanied by cutaneous vasodilation above, hypertension, and bradycardia. This is the result of reflex sympathetic stimulation below the lesion unmodulated by supraspinal influence from above. (See page 1028: Autonomic Hyperreflexia.) 26. Which of the following statements regarding postoperative visual loss is/are TRUE? 1. It occurs in surgeries with long durations. 2. It is commonly bilateral.
3. It is caused by ischemic optic neuropathy. 4. It is always associated with pressure on the eyes from positioning errors. 26. A. The complication of postoperative visual loss is of particular concern in prone spine surgery, although it can occur in other settings. The visual loss is commonly bilateral and is caused by ischemic optic neuropathy, although retinal artery occlusion and cortical blindness may also occur. These incidents of visual loss occur despite the absence of pressure on the eyes from positioning errors, which would result in central retinal artery thrombosis rather than anterior or posterior ischemic optic neuropathy. Ischemic optic neuropathy is associated with blood loss, hypotension, and surgery of long duration in the prone position. It most certainly has a multifactorial cause, including anatomic variation in the vasculature of individual patients. (See page 1028: Postoperative Visual Loss.)
Chapter 40 Anesthesia for Thoracic Surgery 1. The leading cause of cancer mortality in the United States is: A. lung cancer B. colorectal cancer C. breast cancer D. prostate cancer E. none of the above 1. A. Lung cancer has long been the most common cause of cancer mortality in the United States. In 2004, which was the most recent year in which statistics are available from the Centers for Disease Control and Prevention, 108,355 men and 87,897 women were diagnosed with lung cancer. In that year, lung cancer caused more deaths than breast, prostate, and colon cancer combined. (See page 1032: Key Points.) 2. The leading cause of cancer death in women in the United States is: A. lung cancer B. colorectal cancer C. breast cancer D. ovarian cancer E. none of the above 2. A. In 1987, lung cancer surpassed breast cancer as the leading cause of cancer death in women in the United States. (See page 1032: Key Points.) 3. During a preanesthetic interview, you elicit the history of severe exertional dyspnea from an elderly man who smokes cigarettes. This implies:
A. He is at increased risk of high peak airway pressures on mechanical ventilation. B. Wet crackles will be heard at his lung bases on auscultation. C. Preoperative flow volume loops will demonstrate a restrictive pattern. D. He has a severely diminished respiratory reserve and is at high risk of postoperative ventilatory support. E. He will require mechanical ventilatory tidal volumes of 15 to 20 mL/kg. 3. D. During all preanesthetic assessments, it is important to ask about dyspnea. Dyspnea is a sensation of shortness of breath that occurs when a patient's requirement for ventilation is greater than his or her ability to respond to that demand. When the anesthesiologist quantitates the degree of physical activity required to produce the sensation of dyspnea, certain postoperative predictions can be made. After a patient complains of dyspnea produced by minimal exertion, the ventilatory reserve is implicitly significantly diminished, and the forced expiratory volume in one second (FEV1) is predicted to be less than 1500 mL. It is not unusual for these patients to need postoperative ventilatory support. (See page 1033: Preoperative Evaluation.) 4. Acute lung injury, an early form of acute respiratory distress syndrome, is sometimes seen after thoracic surgery. Risk factors for acute lung injury after chest surgery include: A. alcohol abuse B. planned pneumonectomy C. high intraoperative ventilatory pressures D. excessive amounts of fluid administration E. all of the above 4. E. Patients with a preoperative history of alcohol abuse have been identified as being at increased risk for acute lung injury after thoracic surgery. Patients who undergo pneumonectomy, who are exposed to high airway pressures on mechanical ventilation, or who receive an excessive
amount of fluid relative to their needs have also been identified as being at increased risk for acute lung injury. (See page 1033: History.) 5. Which statement regarding the physical examination of a patient undergoing thoracic surgery is FALSE? A. Deviation of the trachea indicates potentially difficult intubation. B. Clubbing is often seen in patients with a left-to-right shunt. C. If cyanosis is present, the patient's PaO2 level is typically below 55 mm Hg. D. The compliance of the pulmonary circulation is reduced in patients with chronic obstructive pulmonary disease (COPD). E. A narrowly split second heart sound is a sign of pulmonary hypertension. 5. B. Clubbing is seen frequently in patients with congenital heart disease associated with a right-to-left shunt, in patients with chronic lung disease, and in patients with malignancies. If cyanosis is present, the arterial saturation is 80% or less, which correlates with a PaO2 level of 50 to 52 mm Hg. Displacement of the trachea should alert the anesthesiologist to the potential for difficult intubation. Patients with COPD have reduced compliance of the pulmonary capillary bed. A narrowly split second heart sound is a sign of pulmonary hypertension. (See page 1033: Respiratory Pattern: Evaluation of the Cardiovascular System.) 6. Which of the following can increase pulmonary vascular resistance? A. Systemic acidemia B. Septicemia C. Systemic hypoxia D. Positive end-expiratory pressure (PEEP) E. All of the above 6. E. Systemic acidosis, sepsis, hypoxemia, and PEEP may increase pulmonary vascular resistance, which may place the patient at risk of right ventricular failure. This risk of right ventricular failure is further
increased if the patient had chronic obstructive pulmonary disease characterized by distention of the pulmonary capillary bed with decreased compliance in response to increased pulmonary blood flow. (See page 1034: Evaluation of the Cardiovascular System.) 7. Which statement regarding flow–volume loops is FALSE? A. Small airway resistance is best displayed at expiration between 25% and 75% of vital capacity. B. Lung volume is displayed on the horizontal axis. C. Patients with restrictive lung disease have a decreased maximum midexpiratory flow rate. D. The flow–volume loop displays essentially the same information as the spirometer. E. Effort-dependent areas of the loop determine large airway patency. 7. C. In patients with restrictive lung disease, the maximum midexpiratory flow rate is usually normal, but total lung capacity is reduced. Lung volume is displayed on the horizontal axis of a flow– volume curve, and flow is displayed on the vertical axis. The shape and peak of flow rates during expiration at high volumes are effort dependent and indicate the patency of the larger airways. Effortindependent expiration occurs at low lung volumes and usually reflects smaller airway resistance. The best measurement for small airway disease is a maximum midexpiratory flow rate of 25% to 75% of vital capacity. The flow–volume loop essentially displays the same information as the spirometer but is more convenient for measurement of specific flow rates. (See page 1035: Flow–Volume Loops.) 8. All of the following statements regarding the treatment of wheezing are true EXCEPT: A. Ipratropium bromide causes bronchodilation by increasing 3′5′cyclic guanosine monophosphate levels. B. Aminophylline should be used cautiously in patients with myocardial ischemia.
P
C. Cromolyn sodium is of little value in the treatment of acute wheezing episodes. D. Steroids decrease mucosal edema and prevent the release of bronchoconstricting substances. E. β-Agonist aerosols cause bronchodilation by increasing 3′5′cyclic adenosine monophosphate levels. 8. A. Ipratropium bromide blocks the formation of 3′5′-cyclic guanosine monophosphate and therefore has a bronchodilatory effect. The balance between 3′5′-cyclic adenosine monophosphate (which produces bronchodilation) and 3′5′-cyclic guanosine monophosphate (which produces bronchoconstriction) determines the state of contraction of the bronchial smooth muscle. Aminophylline may cause ventricular dysrhythmias, so it should be used cautiously when treating patients with cardiac disease. Steroids decrease mucosal edema and prevent the release of bronchoconstricting substances. Cromolyn sodium stabilizes the mast cells and inhibits degranulation and histamine release. It is useful in the prevention of bronchospastic attacks but is of little value in the treatment of acute exacerbations. (See page 1037: Wheezing and Bronchodilation.) 9. The following are true regarding intraoperative monitoring during thoracic surgery EXCEPT: A. Pulmonary artery (PA) catheters often cannot be relied on to accurately assess left ventricular end-diastolic volume (LVEDV). B. The central venous pressure (CVP) is helpful in determining right ventricular performance. C. A central line placed in the external jugular vein often kinks after patient positioning. D. The CVP has been shown to have a poor correlation with left atrial pressure in patients with pulmonary disease. E. Patients with chronic obstructive pulmonary disease (COPD) presenting for lung resection usually have a left-sided heart strain pattern on the electrocardiogram (ECG). 9. E. Patients presenting for lung surgery often have COPD owing to cigarette smoking and right-sided heart strain evident on the ECG. A CVP
catheter reflects blood volume, right ventricular performance, and venous tone. The major disadvantage of using the external jugular vein for placement of a CVP is that the catheter may kink when the patient is turned laterally. The CVP has been shown to have poor correlation with the left atrial pressure in patients with pulmonary disease. A major limitation of the PA catheter is the assumption that the pulmonary capillary wedge pressure provides a good approximation of LVEDV. (See page 1038: Intraoperative Monitoring.) 10. Pulmonary artery (PA) catheters: A. are most often directed to the left upper lobe B. should lie in the nondependent lung when one-lung ventilation is used C. are most reliably inserted through the right internal jugular vein D. yield inaccurate data when placed in the dependent lung E. provide a good approximation of left ventricular end-diastolic volume (LVEDV) 10. C. The tip of a flow-directed PA catheter usually ends up in the right lower lobe because this is the area of highest pulmonary blood flow. The PA catheter is most reliably inserted through the right internal jugular vein using a modified Seldinger technique. During thoracotomy with onelung ventilation, a catheter in the dependent lung should produce accurate hemodynamic measurements. A major limitation of PA catheters is the assumption that the pulmonary capillary wedge pressure (PCWP) provides a good approximation of LVEDV. The use of PCWP directly to assess preload assumes a linear relationship between ventricular end-diastolic volume and ventricular end-diastolic pressure. However, alterations in ventricular compliance affect this pressure– volume relationship during surgery. Decreases in ventricular compliance may occur with myocardial ischemia, shock, right ventricular overload, or pericardial effusion. (See page 1039: Pulmonary Artery Catheterization.) 11. Which of the following is TRUE regarding the diffusing capacity for carbon monoxide (DLCO)?
A. A preoperative DLCO less than 60% of predicted indicates high risk of mortality after lung resection. B. DLCO testing is of little clinical use. C. DLCO correlates well with forced expiratory volume in 1 second (FEV1). D. It is impaired by interstitial lung disease. E. Predicted postoperative diffusing capacity percent is a poor predictor of mortality after lung resection. 11. D. Gas exchange ability by the lungs can be evaluated by testing the DLCO. This parameter is impaired in disorders such as interstitial lung disease. If the tested DLCO is less than 40%, there is an increased risk of postoperative respiratory complications and mortality after lung resection surgery. Little relationship exists between predicted postoperative DLCO and predicted postoperative FEV1. Predicted postoperative diffusing capacity percent is the strongest single predictor of risk of complications and mortality after lung resection. (See page 1036: Diffusing Capacity for Carbon Monoxide.) 12. With respect to the intraoperative use of transesophageal echocardiography (TEE), which of the following statements is FALSE? A. TEE is useful for detecting ventricular dysfunction. B. Peripheral and central lung tumors are equally easy to locate with TEE. C. TEE may be used to detect pulmonary artery compression by a mediastinal tumor. D. TEE can help determine whether cardiopulmonary bypass is necessary for tumor resection. E. Aortic dissection may be diagnosed with TEE. 12. B. TEE can consistently locate central lung tumors, but peripheral lung tumors are located only 30% of the time. TEE is a useful intraoperative monitor for ventricular function, valvular function, and wall motion abnormalities. TEE may help determine when cardiopulmonary bypass is necessary for mediastinal tumor resection. TEE may also show mediastinal tumors compressing the pulmonary
artery. In an exploratory thoracotomy for hemothorax, intraoperative TEE revealed the presence of a subacute aortic dissection, which was believed to be the cause of the hemothorax. (See page 1039: Transesophageal Echocardiography.) 13. Which of the following statements is TRUE regarding changes seen when a patient is positioned in the lateral decubitus position? A. Blood flow to the nondependent lung is significantly greater than it is to the dependent lung. B. The distribution of blood flow is turned by 180 degrees compared with the supine position. C. An awake, spontaneously breathing patient will demonstrate poor ventilation–perfusion matching in the dependent lung. D. Ventilation in the dependent lung is greater than in the nondependent lung. E. The nondependent hemidiaphragm is displaced higher into the chest. 13. D. In the lateral decubitus position, blood flow and ventilation to the dependent lung are significantly greater than to the nondependent lung. In the lateral decubitus position, the distribution of blood flow and ventilation is similar to that in the upright position but turned by 90 degrees. Good ventilation–perfusion matching at the level of the dependent lung results in adequate oxygenation in the awake, spontaneously breathing patient. The dependent hemidiaphragm is pushed higher into the chest by the abdominal contents than is the nondependent diaphragm. (See page 1040: Physiology of One-Lung Ventilation, Lateral Position, Awake, Breathing Spontaneous, Chest Closed.) 14. A patient undergoing a right thoracotomy with one-lung ventilation is given vecuronium bromide and is placed in the left lateral decubitus position. The following statements are true EXCEPT: A. Thirty-five percent of the cardiac output participates in gas exchange in the left lung. B. Hypoxic pulmonary vasoconstriction reduces blood flow to the nondependent hypoxic lung by 50%.
C. The patient's functional residual capacity (FRC) is reduced by receiving vecuronium bromide. D. One-lung ventilation causes a right-to-left shunt in the nonventilated lung. E. Atelectasis may inhibit optimal ventilation to the dependent lung. 14. A. Before the initiation of one-lung anesthesia, the average percentage of cardiac output participating in gas exchange is 35% in the nondependent lung and 60% in the dependent lung. After the initiation of one-lung anesthesia, hypoxic pulmonary vasoconstriction reduces the blood flow to the nondependent lung by 50%. The FRC and the total lung volume decrease during one-lung ventilation. There are several reasons for this, including general anesthesia, paralysis, pressure from the abdominal contents, compression by the weight of mediastinal structures, and suboptimal positioning on the operating table. Atelectasis is one cause of suboptimal ventilation to the dependent lung. (See page 1040: Physiology of One-Lung Ventilation, One-Lung Ventilation, Anesthetized, Paralyzed, Chest Open.) 15. When positioning a double-lumen tube: A. insertion through the vocal cords is performed with the distal curvature facing laterally B. the tube should be advanced until moderate resistance is encountered C. the Miller laryngoscope blade yields a much easier tube insertion than does a Macintosh laryngoscope blade D. the stylet should be removed after the tube is rotated 90 degrees E. a left-sided tube should be rotated 90 degrees to the right after the tip passes through the vocal cords 15. B. Advancement of a double-lumen tube should be stopped when moderate resistance to further passage is encountered, which indicates that the tube tip has been seated in the stem bronchus. A Macintosh laryngoscope blade is preferred for intubation with a double-lumen tube because it provides the largest area through which to pass the tube. The
insertion of the tube between the vocal cords is performed with the distal concave curvature facing anteriorly. It is important to remove the stylet before rotating or advancing the tube farther to avoid tracheal or bronchial lacerations. After the tip of the tube passes the vocal cords, the stylet is removed. A right-sided tube then is rotated 90 degrees to the right; a left-sided tube is rotated 90 degrees to the left. (See page 1044: Placement of Double-Lumen Tubes.) 16. All the following are absolute indications for one-lung ventilation EXCEPT: A. pneumonectomy B. massive hemorrhage C. bronchopleural fistula D. unilateral abscess E. bronchopulmonary lavage 16. A. In clinical practice, a double-lumen tube is commonly used for lobectomy or pneumonectomy; however, these are relative indications for lung separation. Separation of the lungs to prevent spillage of pus or blood from an infected or bleeding source is an absolute indication for one-lung ventilation. Bronchopleural or bronchocutaneous fistulae represent low-resistance escape pathways for the tidal volume delivered by positive-pressure ventilation. These are both absolute indications for one-lung ventilation. During bronchopulmonary lavage, an effective separation of the lungs is mandatory to avoid accidental spillage of fluid from the lavaged lung to the nondependent ventilated lung. (See page 1042: Absolute Indications for One-Lung Ventilation and page 1043: Relative Indications for One-Lung Ventilation.) P 17. When checking the position of the double-lumen tube, all of the following are true EXCEPT: A. Use of an underwater seal is a good method to verify separation before bronchopulmonary lavage. B. Inflation of the bronchial cuff rarely requires more than 2 mL of air.
C. Selective capnography can be used to ensure correct placement. D. A pediatric bronchoscope should be passed through the tracheal lumen first. E. If breath sounds are not equal after the tracheal cuff is inflated, the tube should be advanced 2 to 3 cm. 17. E. If breath sounds are not equal after the tracheal cuff is inflated, the double-lumen tube is likely too far down. Withdrawing the tube by 2 or 3 cm usually restores equal breath sounds. Inflation of the bronchial cuff rarely requires more than 2 mL of air. The bronchoscope usually is introduced first through the tracheal lumen. The carina is visualized, and bronchial cuff herniation should not be seen. Common methods of ensuring the correct placement of a double-lumen tube include fluoroscopy, chest radiography, selective capnography, and the use of an underwater seal. If the bronchial cuff is not inflated and positivepressure ventilation is applied to the bronchial lumen of the doublelumen tube, gas will leak past the bronchial cuff and will return to the tracheal lumen. If the tracheal lumen is connected to an underwater seal system, gas will be seen bubbling up through the water. The bronchial cuff can then be gradually inflated until no gas bubbles are seen. (See page 1044: Placement of Double-Lumen Tubes.) 18. All of the following inhibit hypoxic pulmonary vasoconstriction EXCEPT: A. propofol B. pulmonary embolism C. epinephrine D. mitral stenosis E. infection 18. A. It is generally believed that inhaled agents inhibit human papillomavirus (HPV), but intravenous drugs do not have this effect. Factors associated with an increase in pulmonary artery pressure antagonize the effects of increased resistance caused by hypoxic pulmonary vasoconstriction and result in increased flow to the hypoxic region. Indirect inhibitors of hypoxic pulmonary vasoconstriction include
mitral stenosis, thromboembolism, and vasopressors such as epinephrine. Direct inhibitors of hypoxic pulmonary vasoconstriction include infection and vasodilator drugs. (See page 1054: Effects of Anesthetics and Hypoxic Pulmonary Vasoconstriction.) 19. All of the following are true regarding patients with mediastinal masses EXCEPT: A. Local anesthesia is an anesthetic option for biopsy. B. Airway obstruction on induction of anesthesia may be relieved with neuromuscular blocking agents. C. Hypotension on induction of anesthesia may be secondary to cardiac compression. D. Mediastinal masses may coexist with superior vena cava syndrome. E. Passage of a rigid bronchoscope beyond the obstruction may be lifesaving. 19. B. When a patient has a mediastinal mass and there is concern that airway obstruction may occur during anesthetic induction, an awake fiberoptic intubation is the technique of choice. Spontaneous respiration should be maintained because muscle paralysis may result in airway compression and may worsen the obstruction. Ventilatory difficulties may be relieved by passing the rigid bronchoscope beyond the obstruction under direct laryngoscopy or by changing the patient's position. Mediastinal masses may cause superior vena cava syndrome. Cardiac compression may become apparent after the induction of anesthesia. (See page 1058: Diagnostic Procedures for Mediastinal Masses.) 20. Mediastinoscopy: A. commonly occludes the left radial pulse B. may be associated with right hemiparesis C. may cause injury to the superior laryngeal nerve D. is a procedure with potential for life-threatening hemorrhage E. must be performed with the patient under general anesthesia
20. D. Mediastinoscopy is a means of assessing the spread of lung carcinoma. Hemorrhage is a real risk and may be life threatening, so blood must be available. Pressure on the innominate artery by the mediastinoscope has been thought to cause transient left hemiparesis; therefore, it is recommended that blood pressure be monitored in the left arm and that the right radial pulse be monitored continuously. Recurrent laryngeal nerve injury may occur either secondary to damage by the mediastinoscope or by tumor involvement. If both recurrent laryngeal nerves are damaged, upper airway obstruction may result. Most surgeons and anesthesiologists prefer general anesthesia using an endotracheal tube and continuous ventilation because this offers a more controlled situation and greater flexibility in terms of surgical manipulation. (See page 1059: Mediastinoscopy.) 21. Regarding lung volume reduction surgery, all of the following are true EXCEPT: A. This procedure is necessary in patients with end-stage emphysema. B. Ventilation can usually be decreased after the chest is open. C. Nitrous oxide should be avoided. D. Pneumothorax may be difficult to diagnose. E. Patients have a greater amount of functional lung tissue after surgery. 21. B. Extensive bullae represent end-stage emphysematous destruction of the lung. After the chest is open during lung volume reduction surgery, more of the tidal volume may enter the compliant bullae, which are no longer limited by chest wall integrity, and an increase in ventilation is needed until the bullae are resected. Nitrous oxide should be avoided because it may cause expansion of the bullae. The diagnosis of pneumothorax may be made by a unilateral decrease in breath sounds (which may be difficult to distinguish in a patient with bullous disease). Unlike most cases of pulmonary resection, after bullectomy, patients are left with a greater amount of functional lung tissue than was previously available to them, and the mechanics of respiration are improved. (See page 1062: Lung Cysts and Bullae.)
22. Which of the following statements regarding bronchopulmonary lavage is TRUE? A. The cuff seal of an endobronchial tube should be adjusted so that no leak is present at 50 cm H2O. B. Most patients require 3 days of mechanical ventilation after lavage. C. The patient is turned so the lavage side is uppermost. D. After lung separation is achieved while the patient is under general anesthesia, the patient is allowed to regain consciousness for the procedure. E. The onset of rales in the ventilated lung indicates heart failure. 22. A. During bronchopulmonary lavage, the cuff seal should be checked to maintain perfect separation of lungs at a pressure of 50 cm H2O to prevent leakage of lavage fluid. A stethoscope should be placed over the ventilated lung to check for rales that may indicate leakage of lavage fluid into this lung. After the trachea is intubated, the patient is turned so the side to be treated is lowermost, and the double-lumen tube position and seal are checked again. After another period of ventilation, most patients can be extubated in the operating room. (See page 1063: Bronchopulmonary Lavage.) 23. Which of the following statements regarding fiberoptic bronchoscopy is FALSE? A. Suction through the bronchoscope leads to a decreased PaO2. B. Airway obstruction after fiberoptic bronchoscopy is a rare complication. C. Positive end-expiratory pressure (PEEP) should be discontinued before passage of the fiberscope. D. The adult fiberscope can pass through a 7.5-mm endotracheal tube. E. Jet ventilation may be achieved by attachment to the suction channel.
23. B. During and after fiberoptic bronchoscopy, patients experience increased airway obstruction. These changes are believed to be secondary to direct mechanical activation of irritative reflexes in the airway and possibly to mucosal edema. The standard adult fiberoptic bronchoscope has an external diameter of 5.7 mm and a 2-mm diameter suction channel. If suction at 1 atm is applied to the fiberscope, air is removed at a rate of 14 L/min. If the fiberscope is in the airway, this causes decreases in the fraction of inspired oxygen (FIO2), PAO2, and functional residual capacity, leading to decreased PaO2. Therefore, suctioning should be kept brief. The adult fiberscope can be passed through endotracheal tubes of 7 mm or greater internal diameter. Clearly, passage through an endotracheal tube decreases the crosssectional area available for ventilating the patient, so if fiberoscopy is planned, an endotracheal tube of the largest possible diameter should be used. Insertion of the bronchoscope also causes a significant PEEP effect that may result in barotrauma in ventilated patients. If PEEP is already being used, it should be discontinued before passage of the fiberscope. Post-endoscopy chest radiography is advisable to exclude the presence of mediastinal emphysema or pneumothorax. The suction channel of the adult fiberoptic bronchoscope has been used to oxygenate and ventilate the lungs of patients. (See page 1056: Anesthesia for Diagnostic Procedures and page 1057: Fiberoptic Bronchoscopy.) 24. Which of the following statements regarding choice of anesthesia for thoracic surgery is FALSE? A. Ketamine produces bronchodilation. B. Remifentanil in combination with propofol significantly blunts hypoxic pulmonary vasoconstriction. C. Rocuronium is a preferred neuromuscular blocking agent. D. Isoflurane may be beneficial because it increases the cardiac arrhythmia threshold. E. Morphine may cause bronchoconstriction. 24. B. The potent inhaled anesthetic agents have all been shown to decrease airway reactivity and bronchoconstriction provoked by hypocapnia or inhaled or irritant aerosols. Their mechanism of action is
probably a direct one on the airway musculature itself, and potent inhaled anesthetic agents are therefore the drugs of choice in patients with reactive airways. For an inhalation induction, halothane or sevoflurane may be preferable because they are the least pungent of the three drugs, although after the patient is asleep, isoflurane may be the preferred drug because it increases the cardiac arrhythmia threshold and provides greater cardiovascular stability than halothane. Fentanyl does not appear to influence bronchomotor tone, but morphine may increase tone by a central vagotonic effect and by releasing histamine. In patients with reactive airways, ketamine may be the drug of choice for induction because it has a bronchodilator effect and has been successfully used in the treatment of patients with asthma. Propofol infused in doses of 6 to 12 mg/kg/hr does not abolish HPV during onelung ventilation in humans. Propofol infusion in combination with remifentanil is probably the technique of choice for producing a stable OLV with no effect on HPV. (See page 1053: Choice of Anesthesia for Thoracic Surgery.) For questions 25 to 39, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 25. The goals of performing pulmonary function tests (PFTs) in patients scheduled for lung resection for treatment of a malignancy are to: 1. establish the maximum amount of resectable lung tissue 2. identify patients needing postoperative ventilatory support 3. evaluate the benefits of bronchodilators in reversing existing airway obstruction 4. evaluate whether increased inspired O2 concentration increases ventilation and therefore the work of breathing 25. A. Preoperative PFTs allow the surgeon and anesthesiologist to determine the maximum amount of resectable lung before the patient would become a pulmonary cripple. If the amount of planned resection would cause significant morbidity, then reconsideration of the surgical plan may be in order. PFTs also allow one to plan for postoperative ventilatory support after lung resection. Preoperative PFTs also evaluate
whether the patient exhibits airway obstruction and whether that obstruction reverses completely or partly after bronchodilator therapy. (See page 1034: Pulmonary Function Testing and Evaluation for Lung Resectability.) 26. Which of the following sympathomimetic drugs are β 2-selective and produce minimal cardiac effect from β 1-stimulation? 1. Albuterol 2. Terbutaline P 3. Metaproterenol 4. Epinephrine 26. A. Albuterol, terbutaline, and metaproterenol are β 2-selective sympathomimetic drugs that have little effect on β 1-receptors (cardiac receptors). They are used to increase intracellular cyclic adenosine monophosphate concentrations in bronchial smooth muscle and thereby produce bronchodilation. Epinephrine stimulates both β 1- and β 2receptors. (See page 1037: Wheezing and Bronchodilation.) 27. Respiratory changes that occur after lower abdominal surgery include: 1. Total lung capacity decreases to the same extent after abdominal surgery as after extremity surgery. 2. Tidal volume is decreased for approximately 2 weeks. 3. Pulmonary compliance increases. 4. Vital capacity decreases by 25%. 27. C. Tidal volume decreases by 20% within 24 hours after surgery and gradually returns to normal after 2 weeks. Vital capacity is decreased by 25% to 50% within 1 to 2 days after surgery and generally returns to normal after 1 to 2 weeks. Pulmonary compliance decreases by 33% with similar reductions in functional residual capacity. Total lung capacity decreases after abdominal surgery but not after extremity surgery. (See page 1034: Effects of Anesthesia and Surgery on Lung Volume.)
28. Which of the following statements regarding pulmonary evaluation for lung resectability is/are TRUE? 1. It is more useful to use the percent of predicted forced expiratory volume in 1 second (FEV1) rather than the absolute value. 2. A patient with an abnormal vital capacity has a 33% likelihood of complications. 3. An FEV1 of less than 800 mL in a 70-kg patient is an absolute contraindication to lung resection. 4. A ratio of residual volume to total lung capacity of 10% is consistent with a high risk for pulmonary resection. 28. A. A patient with an abnormal vital capacity has a 33% likelihood of complications and a 10% risk of postoperative mortality. An FEV1 of less than 800 mL in a 70-kg patient is probably incompatible with life and is an absolute contraindication to lung resection. It is preferable to indicate the percentage of predicted rather than just using the absolute value. The percentage of predicted takes into account the age and size of the patient, and the same number may have a different implication in another patient. A ratio of residual volume to total lung capacity of more than 50% indicates a patient who is at high risk for pulmonary resection. (See page 1035: Spirometry.) 29. Which of the following statements concerning smoking is/are TRUE? 1. Smoking decreases forced vital capacity and maximum midexpiratory flow rate. 2. Cessation of smoking for 48 hours before surgery shifts the oxyhemoglobin curve to the left. 3. Most of the beneficial effects of smoking cessation do not occur before 2 to 3 months. 4. Smoking increases mucociliary transport. 29. B. Most of the beneficial effects of smoking cessation, such as improvement in ciliary function, improvement in closing volume, increased maximum midexpiratory flow rate, and reduction in sputum,
usually occur 2 to 3 months after smoking cessation. Smoking increases airway irritability, decreases mucociliary transport, and increases secretions. Smoking also decreases forced vital capacity. Smoking cessation 48 hours before surgery has been shown to decrease the level of carboxyhemoglobin and to shift the oxyhemoglobin dissociation curve to the right, thus increasing O2 availability. (See page 1036: Smoking.) 30. Which of the following statements concerning oxygenation and ventilation is/are TRUE? 1. Arterial blood gases are unnecessary as long as end-tidal CO2 is monitored. 2. The alveolar dead space affects the arterial–alveolar CO2 gradient. 3. Hypercarbia is usually a greater problem than systemic hypoxia during one-lung ventilation. 4. CO2 readings may help indicate correct double-lumen tube placement. 30. C. Normally, a small arterial–alveolar CO2 gradient of approximately 4 to 6 mm Hg is dependent on the alveolar dead space. The capnogram waveform is helpful in diagnosing airway obstruction, incomplete relaxation, and incorrect positioning of the double-lumen tube. Adequacy of ventilation should be confirmed by monitoring arterial blood gases and PaCO2, in particular. This may be estimated continuously and noninvasively by using capnography. During one-lung ventilation, systemic hypoxia is usually a greater problem than hypercarbia, making it necessary to monitor arterial oxygenation. This is because CO2 is 20 times more diffusible than O2; arterial CO2 concentration is more dependent on ventilation, but arterial O2 concentration is more dependent on perfusion. (See page 1039: Monitoring of Oxygenation and Ventilation.) 31. Which of the following statements regarding bronchial blockers is/are TRUE? 1. They are effective in maintaining lung isolation despite surgical manipulation.
2. An advantage is that they are useful in patients with difficult airways. 3. Placement of an endobronchial catheter into the bronchus should be performed blindly. 4. A bronchial blocker may be used in a 12-year-old child. 31. C. The Univent tube may be helpful for cases in which changing the double-lumen tube to a single-lumen tube may be difficult (e.g., after bilateral lung transplantation). The Univent tube is a single-lumen endotracheal tube with a movable endobronchial blocker. An independently passed bronchial blocker may be used with a single-lumen tube to obtain lung isolation, thereby avoiding the use of a doublelumen tube in a patient with a difficult airway. The bronchial blocker technique may be useful in achieving selective ventilation in adults and may be used in children younger than 12 years old. It should be placed via bronchoscopic guidance. These tubes are not used very commonly because they are easily displaced. Displacement of the bronchial blocker necessitates a pause in surgery while it is replaced under bronchoscopic guidance. (See page 1043: Methods of Lung Separation.) 32. During one-lung ventilation: 1. tidal volumes should be adjusted to 10 to 12 mL/kg 2. continuous positive airway pressure (CPAP) to the nondependent lung increases arterial O2 concentration 3. hyperventilation can lead to a decreased PaO2 level 4. a fraction of inspired oxygen (FIO2) of 1.0 is frequently used 32. E. During one-lung ventilation, the dependent lung should be ventilated with a tidal volume of 10 to 12 mL/ kg. The single most effective maneuver to increase arterial O2 concentration during one-lung ventilation is the application of CPAP to the nondependent lung. It is important not to hyperventilate the patient's lungs because hypocapnia will increase vascular resistance in the dependent lung, inhibit nondependent lung hypoxic pulmonary vasoconstriction, increase the shunt, and therefore decrease the PaO2 concentration. An FIO2 of 1.0 is usually used during one-lung ventilation. This high oxygen concentration
serves to protect against hypoxemia during the procedure. (See page 1051: Tidal Volume and Respiratory Rate and page 1052: Continuous Positive Airway Pressure to the Nondependent Lung.) 33. Hypoxic pulmonary vasoconstriction: 1. is increased in the presence of potent inhaled anesthetics 2. is indirectly inhibited by hypothermia 3. is inhibited by volume overload 4. is activated by collapse of the nondependent lung 33. C. Normally, collapse of the nonventilated, nondependent lung results in the activation of reflex hypoxic pulmonary vasoconstriction. Some indirect inhibitors of hypoxic pulmonary vasoconstriction include volume overload, thromboembolism, and hypothermia. (See page 1054: Hypoxic Pulmonary Vasoconstriction.) 34. Rigid bronchoscopy is the procedure of choice for: 1. assessing vascular tumors of the lower airway 2. securing an airway in a difficult intubation 3. bronchoscopy in small children 4. evaluation of upper lobe lesions 34. B. The rigid bronchoscope is the instrument of choice for removal of foreign bodies, control of massive hemoptysis, assessment of vascular tumors, bronchoscopy in small children, and resection of endobronchial lesions. Flexible bronchoscopy is useful in evaluating upper lobe lesions and in securing an airway in difficult intubations. (See page 1056: Table 40-4: Anesthesia for Diagnostic Procedures.) 35. Which of the following statements regarding myasthenia gravis is/are TRUE? 1. Examination of pupillary size may differentiate between myasthenic and cholinergic crisis. 2. These patients are very sensitive to depolarizing muscle relaxants and are resistant to nondepolarizing muscle relaxants.
3. Thymectomy is considered to be the treatment of choice in many patients with generalized myasthenia gravis. 4. This condition is associated with a markedly decreased release of acetylcholine from nerve terminals. 35. B. The distinction between a myasthenic crisis and a cholinergic crisis may be made using a Tensilon test or by examining pupillary size (which is large during a myasthenic crisis but small during a cholinergic crisis). Thymectomy is now considered the treatment of choice in many patients with myasthenia gravis. Patients with myasthenia gravis are sensitive to the nondepolarizing relaxants and are resistant to succinylcholine. The basic abnormality in myasthenia gravis is a decrease in the number of postsynaptic acetylcholine receptors at the end plates of the affected muscles. Myasthenia gravis is an autoimmune disorder, and most affected patients have circulating antibodies to the acetylcholine receptors. (See page 1064: Myasthenia Gravis.) 36. Which of the following statements regarding video-assisted thoracoscopic surgery (VATS) is/are TRUE? 1. CO2 may be insufflated into the pleural cavity. 2. Continuous positive airway pressure (CPAP) may interfere with the surgical procedure. 3. The need for one-lung ventilation is greater for VATS than for open thoracotomy. 4. It may take 30 minutes for complete lung collapse. 36. E. During VATS, CO2 may be insufflated into the pleural cavity to help visualization by the surgeon. CPAP may interfere with the surgical procedure and should be used only as a last resort in VATS. The need for one-lung ventilation is greater with VATS than with open thoracotomy because it is not possible to retract the lung during VATS, although it is possible during open thoracotomy. It may take 30 minutes for complete lung collapse; thus, the operated lung should be deflated as soon as possible after tracheal intubation and positioning of the double-lumen tube. (See page 1060: Video-Assisted Thoracoscopic Surgery.) 37. Which of the following statements about central venous pressure (CVP) monitoring is/are TRUE?
1. It reflects right-sided heart function. 2. One common use is for the infusion of vasoactive drugs. 3. A CVP catheter can be place from either the internal or external jugular vein. 4. It reliably reflects intravascular status. 37. A. The CVP reflects right-sided heart function, not left ventricular performance. Uses of CVP catheters or large-bore introducers include insertion of a transvenous pacemaker, infusion of vasoactive drugs, and insertion of a pulmonary artery (PA) catheter, which may subsequently be required during surgery or in the postoperative period. A recent study in healthy subjects indicated that contrary to common belief, the CVP did not reflect intravascular volume status. The CVP catheter may be placed centrally from the external or the internal jugular vein, from the subclavian veins, or from one of the arm veins. The success rate is highest using the right internal jugular vein, and a pacemaker or PA catheter may be inserted most easily from this vein. The major disadvantage of using the external jugular vein during thoracotomy is that the catheter often kinks when the patient is turned to the lateral decubitus position. (See page 1038: Central Venous Pressure Monitoring.) P 38. Which of the following statements about double-lumen endobronchial tubes (DLT) is/are TRUE? 1. The depth required for insertion of the tube correlates with the patient's height. 2. A left-sided tube is preferred for both right- and left-sided procedures. 3. The width of the left bronchus is directly proportional to the width of the trachea. 4. A 37-Fr double-lumen tube is the correct size for most women. 38. E. Because the left main bronchus is considerably longer than the right bronchus, there is a narrower margin of safety on the right main bronchus with potentially a greater risk of upper lobe obstruction whenever a right-sided DLT is used. Hence, a left-sided DLT is preferred for both right- and left-sided procedures. In patients in whom the left
main bronchus cannot be directly measured, the left bronchial diameter can be accurately estimated by measuring tracheal width. The width of the left bronchus is directly proportional to the width of the trachea. The left bronchial width is estimated by multiplying the tracheal width by 0.68. Typically, most women need a 37-Fr DLT, and most men can be adequately managed with a 39-Fr DLT. The depth required for insertion of the DLT correlates with the height of the patient. For any adult who is 170 to 180 cm tall, the average depth for a left DLT is 29 cm. For every 10-cm increase or decrease in height, the DLT is advanced or withdrawn approximately 1.0 cm. (See page X: Methods of Lung Separation and page 1043: Double-Lumen Endobronchial Tubes.) 39. Which of the following statements concerning malposition of a double-lumen tube (DLT) is/are TRUE? 1. If the DLT is not inserted far enough, breath sounds are not audible over the contralateral side. 2. The mean distance from the carina to the right upper lobe orifice is 2 to 3 cm. 3. If the DLT is inserted too far down either bronchus, breath sounds will be heard bilaterally when ventilating through the bronchial lumen. 4. Tracheal rupture is a rare complication. 39. C. Upon insertion, the DLT may be passed too far down into either the right or the left mainstem bronchus. In this case, breath sounds are very diminished or are not audible over the contralateral side. This situation is corrected when the tube is withdrawn and until the opening of the tracheal lumen is above the carina. A right-sided DLT may occlude the right upper lobe orifice. The mean distance from the carina to the right upper lobe orifice is 2.3 ± 0.7 cm in men and 2.1 ± 0.7 cm in women. Upon insertion, the DLT may not be inserted far enough, leaving the bronchial lumen opening above the carina. In this position, good breath sounds are heard bilaterally when ventilating through the bronchial lumen even after its cuff is inflated, but no breath sounds are audible when ventilating through the tracheal lumen because the inflated bronchial cuff obstructs gas flow arising from the tracheal lumen. The cuff should be deflated and the DLT rotated and advanced into the desired mainstem bronchus. A rare complication with DLTs is
tracheal rupture. Overinflation of the bronchial cuff, inappropriate positioning, and trauma owing to intraoperative dislocation that resulted in bronchial rupture have been described in association with the Robertshaw tube and the disposable DLT. (See page 1043: Methods of Lung Separation and page 1043: Double-Lumen Endobronchial Tubes.)
Chapter 41 Anesthesia for Cardiac Surgery 1. The area of the myocardium most at risk for ischemia is the: A. right ventricle B. apex of the left ventricle C. interventricular septum D. portion of the right atrium containing the sinoatrial node E. subendocardial region of the left ventricle 1. E. Although zones of ischemic myocardium may result from inadequate coronary blood flow through the vessels supplying each region, the area of myocardium most vulnerable to ischemia is the subendocardial region of the left ventricle. This is not only because of a greater metabolic requirement in the presence of greater systolic shortening but also because subendocardial blood flow is restricted during systole. (See page 1074: Coronary Blood Flow.) 2. The principal determinants of myocardial oxygen demand are: A. wall tension and contractility B. systemic vascular resistance and heart rate C. mean arterial blood pressure and heart rate D. preload and afterload E. mean arterial blood pressure and systemic vascular resistance 2. A. Wall tension and contractility are the principal determinants of myocardial oxygen demand. Wall tension, in turn, is directly proportional to intracavitary pressure and ventricular radius and is inversely proportional to the thickness of the ventricular wall. Therefore, myocardial oxygen demand may be reduced by interventions that prevent or treat ventricular distention and reduce contractility. (See page 1074: Coronary Artery Disease: Myocardial Oxygen Demand.)
3. Under normal conditions, approximately what is the oxygen saturation of blood entering the coronary sinus? A. 10% B. 25% C. 50% D. 75% E. 90% 3. C. Oxygen extraction in the coronary circulation is extremely efficient; blood entering the coronary sinus is typically about 50% saturated. Although extraction may be increased somewhat in response to stress, the principal mechanism by which oxygen supply is increased in response to increased oxygen demand is through an increase in coronary blood flow. (See page 1074: Coronary Artery Disease: Myocardial Oxygen Supply.) 4. Regarding perfusion of the left ventricular subendocardium, which one of the following statements is most accurate? A. It occurs mostly during systole. B. It occurs mostly during diastole. C. It increases with an increase in left ventricular end-diastolic pressure. D. It is unaffected by heart rate. E. It decreases with an increase in aortic diastolic pressure. 4. B. The left ventricular subendocardium is one of the areas of the heart that is most vulnerable to ischemia because of its high metabolic requirements. Perfusion of the subendocardial tissue of the left ventricle takes place mostly during diastole; this is in contrast to perfusion of the right ventricle, which occurs principally during systole. Perfusion pressure is defined as the difference between aortic diastolic pressure and left ventricular end-diastolic pressure. Whereas an increase in aortic diastolic pressure increases perfusion, an increase in left ventricular end-diastolic pressure decreases perfusion. Insofar as changes in heart rate affect diastolic time, changes in heart rate do cause changes in
perfusion. (See page 1074: Coronary Artery Disease: Coronary Blood Flow.) 5. The normal area of the aortic valve is: A. 0.2 to 0.4 mm2 B. 2 to 4 mm2 C. 0.2 to 0.4 cm2 D. 4 to 8 cm E. 2 to 4 cm2 5. E. The normal aortic valve diameter is 1.9 to 2.3 cm, and the normal aortic valve area is 2 to 4 cm2. Aortic stenosis is classified based on the degree of narrowing of the aortic valve area. Aortic stenosis is considered critical when the area of the aortic valve is below 0.8 cm2. Patients with this degree of aortic stenosis are almost always symptomatic, and surgical correction is indicated. (See page 1078: Valvular Heart Disease: Aortic Stenosis.) 6. Which of the following conditions best describes a physiologic change associated with mitral stenosis? A. Left ventricular outflow obstruction B. Left ventricular dysfunction resulting from chronic pressure overload C. Left ventricular dysfunction resulting from chronic volume overload D. Decreased right ventricular pressure E. Increased left atrial pressure and concomitant right ventricular hypertrophy 6. E. In mitral stenosis, left atrial pressure elevation is a consequence of a narrowed mitral orifice. This increased pressure is transmitted back through the pulmonary circulation, leading to right ventricular hypertrophy. Conversely, the left ventricle is not subject to pressure or volume overload, and normal function is generally preserved. (See page 1082: Mitral Stenosis.)
7. An advantage of membrane over bubble oxygenators in cardiopulmonary bypass circuits is: A. The uptake of inhaled anesthetics is more predictable with membrane oxygenators. B. There is less trauma to blood constituents. C. Pulsatile flow is possible with the use of a membrane oxygenator. D. Membrane oxygenators offer a cost advantage over bubble oxygenators. E. Carbon dioxide exchange is significantly more effective. 7. B. Studies comparing the two types of oxygenators reveal less trauma to blood constituents with membrane oxygenators. Hemolysis and the resultant release of red blood cell debris are potential problems associated with bubble oxygenators. Likewise, a decrease in platelet activity resulting from platelet destruction, increased aggregation, and adherence to the oxygenator may lead to impairment of postoperative hemostasis. (See page 1087: Oxygenators.) 8. The most commonly used test to evaluate the adequacy of anticoagulation for cardiopulmonary bypass is: A. heparin concentration assay B. antithrombin III index C. activated partial thromboplastin time (APTT) D. activated clotting time (ACT) E. prothrombin time (PT) 8. D. The ACT indicates the time required for thrombus formation after a sample of whole blood is mixed with a clotting accelerator. A value of more than 400 seconds is generally believed to reflect a degree of anticoagulation that is adequate for cardiopulmonary bypass. (See page 1088: Anticoagulation.) 9. Advantages of centrifugal versus roller pumps cardiopulmonary bypass (CPB) machines include all of the following EXCEPT:
P
A. less blood trauma B. less risk of air emboli C. elimination of tubing wear and the risk of plastic microemboli D. ability to deliver pulsatile blood flow E. reduction in line pressures 9. D. Centrifugal CPB machines operate by a magnetically controlled impeller and an electric motor and are rapidly replacing the older roller pump systems. Advantages of the centrifugal system include less trauma to blood entering the system, lower line pressures, reduced risk of air emboli, and elimination of tubing wear and plastic emboli resulting from tubing compression (spallation). Neither roller pumps nor centrifugal pumps may deliver physiologically significant pulsatile blood flow. (See page 1095: Cardiopulmonary Bypass: Pumps.) 10. For each degree of Celsius decrease in body temperature, metabolic rate is decreased by approximately: A. 1% B. 2% C. 4% D. 8% E. 10% 10. D. For each degree of Celsius decrease in body temperature, there is a reduction of 8% in the metabolic rate. (See page 1095: Cardiopulmonary Bypass: Heat Exchanger.) 11. Nitric oxide dilates pulmonary vascular beds via: A. production of cyclic adenosine monophosphate (cAMP) B. inhibition of cAMP C. production of cyclic guanosine monophosphate (cGMP) D. inhibition of cGMP E. none of the above
11. C. Nitric oxide exerts most of its effects by stimulating the guanylyl cyclase enzyme, leading to increased production of cGMP. In turn, cGMP stimulates phosphodiesterases, which relax vascular smooth muscle, promoting vasodilation. (See page 1095: Cardiopulmonary Bypass.) 12. A patient with previously normal left ventricular function is undergoing elective coronary artery bypass grafting. Immediately after separation from cardiopulmonary bypass (CPB), the following measurements are noted: a blood pressure via radial intra-arterial catheter of 78/52 mm Hg, a heart rate of 94 bpm, a pulmonary artery pressure of 28/18 mm Hg, and a cardiac index of 2.7. The most prudent initial intervention would be: A. direct measurement of intra-aortic pressures to verify radial artery correlation B. the addition of a phenylephrine infusion to provide α receptor–mediated vasoconstriction C. the addition of an epinephrine infusion to provide both inotropic support and α -receptor–mediated vasoconstriction D. an intra-aortic volume infusion using pulmonary capillary wedge pressures as a guide to the adequacy of left ventricular filling E. a trial of atrial pacing after placement of epicardial leads 12. A. Although frequently accurate, radial artery pressure may be as much as 30 mm Hg lower than central aortic pressure after CPB. Peripheral vasodilation during rewarming is thought to be the cause of the discrepancy, which may be readily detected by direct transduction of intra-aortic pressure via the operative field. This aortic–radial pressure gradient usually dissipates within 45 minutes of separation from bypass. (See page 1091: Arterial Blood Pressure.) 13. The most frequent cause of perioperative neurologic complications after coronary artery bypass grafting is: A. changes in carotid artery flow dynamics during aortic crossclamping B. low-flow states in patients with pre-existing cerebrovascular disease
C. emboli D. intraoperative hemodilution E. ischemia to watershed regions of the brain during the rewarming phase of cardiopulmonary bypass 13. C. Although the incidence of stroke after coronary artery bypass grafting is approximately 3%, the incidence of subtle cognitive deficits elicited by postoperative neuropsychiatric testing is much higher (60%– 70%). The origin of perioperative neurologic insults is believed to be primarily embolic. Macroemboli, such as atheroma and particulate matter, account for most overt perioperative strokes. Microemboli (air, platelet aggregates) are likely responsible for the subtle cognitive changes seen after coronary artery bypass grafting. Most neuropsychiatric deficits improve over the initial 2 to 6 months after cardiac surgery, although significant numbers of patients (13%–39%) exhibit residual impairment. (See page 1092: Central Nervous System Function and Complications.) 14. Of the following anesthetic techniques for cardiac surgery, the one associated with the best outcome in terms of perioperative morbidity is: A. a predominantly opioid-based anesthetic in conjunction with benzodiazepines B. a “balanced” anesthetic technique using opioid analgesics combined with potent inhalation agents titrated for varying degrees of stimulation C. continuous high-dose sufentanil infusion D. a predominantly potent inhalation agent–based technique with epidural catheter placement for postoperative analgesia E. none of the above 14. E. Two large outcome studies by Tuman et al. and Slogoff and Keats reinforced the premise that the choice of anesthetic per se has no effect on outcome in patients undergoing cardiac surgery. More important is the ability of the anesthesiologist to preserve compensatory cardiovascular mechanisms while preventing perioperative episodes of myocardial ischemia. Because no data exist to document the superiority
of any one anesthetic technique for cardiac surgery, it becomes apparent that the proper management of the anesthetic is more important than the technique used. (See page 1093: Selection of Anesthetic Drugs.) 15. In the immediate postcardiopulmonary bypass period, milrinone may be particularly useful in the treatment of right ventricular failure secondary to high pulmonary vascular resistance because: A. the positive chronotropic effect of milrinone results in improved cardiac output from the noncompliant right ventricle B. milrinone improves right ventricular contractility while decreasing pulmonary vascular resistance C. milrinone decreases preload to the right ventricle by decreasing resistance in venous capacitance vessels D. the improvement in left ventricular performance afforded by milrinone in turn decreases right ventricular afterload E. all of the above 15. B. A phosphodiesterase III inhibitor, milrinone, acts via a non–β receptor pathway to effect a decrease in pulmonary vascular resistance while improving left and right heart contractility. Such interventions are the treatments of choice in conditions of right ventricular failure secondary to high pulmonary vascular resistance; overdistention of the ventricle is carefully avoided. (See page 1096: Discontinuation of Cardiopulmonary Bypass.) 16. The most common cause of persistent bleeding after heparin reversal in cardiac surgical patients is: A. heparin rebound B. hypothermia C. reduced platelet count or function D. diminished capillary integrity E. inactivation of antithrombin III 16. C. The usual causes of persistent oozing after heparin neutralization include inadequate surgical hemostasis and reduced platelet count or
function, although insufficient doses of protamine, dilution of clotting factors, and (rarely) “heparin rebound” may be contributing factors. Thrombocytopenia and diminished platelet function are frequent consequences of extracorporeal circulation, resulting from platelet activation and destruction when in contact with the bypass circuit. (See page 1100: Postbypass Bleeding.) 17. Compared with volatile anesthetics, which of the following statements about propofol is FALSE? A. Propofol is associated with more favorable cardiac function. B. Propofol is associated with higher need for inotropic support. C. Propofol is associated with elevated plasma troponins after cardiac surgery in elderly patients. D. Propofol is associated with a predictable and fairly rapid awakening after discontinuation. E. Propofol may be continued postoperatively in the intensive care unit (ICU). 17. A. Compared with volatile anesthetics, propofol is associated with less favorable cardiac function, a higher need for inotropic support, and elevated plasma troponins after cardiac surgery in elderly patients. It may be continued postoperatively in the ICU, and it affords a predictable and fairly rapid awakening after discontinuation. (See page 1077: Intravenous Sedatives and Hypnotics.) 18. Which of the following statements regarding magnesium is FALSE? A. It has coronary vasodilating properties. B. It reduces the size of myocardial infarction in the setting of acute ischemia. P C. It acts as an antiarrhythmic agent. D. It decreases mortality associated with infarction. E. It increases myocardial reperfusion injury. 18. E. Magnesium has use in the treatment of myocardial ischemia. It has coronary artery vasodilating properties, reduces the size of
myocardial infarction in the setting of acute ischemia, and decreases mortality associated with infarction. In addition, it is an antiarrhythmic agent, and it minimizes myocardial reperfusion injury. (See page 1077: Treatment of Ischemia.) 19. Which of the following statements regarding hypertrophic cardiomyopathy (HOCM) is FALSE? A. HOCM is a dynamic obstruction. B. The obstruction is attenuated by any intervention that reduces ventricular size. C. HOCM is a genetically determined disease. D. Angina during exercise occurs even in the absence of epicardial coronary artery disease. E. Hypotension is managed with volume replacement and vasoconstrictors. 19. B. Hypertrophic cardiomyopathy is a genetically determined disease. In patients with HOCM, systolic septal bulging into the left ventricular outflow tract (LVOT), malposition of the anterior papillary muscle, drag forces, and a hyperdynamic ventricular contraction may contribute to creation of a LVOT gradient. This type of obstruction is dynamic and is accentuated by any intervention that reduces ventricular size. Therefore, increases in contractility and heart rate or decreases in either preload or afterload are harmful because they facilitate septal– leaflet contact. In patients with HOCM, myocardial oxygen balance is tenuous, and angina during exercise occurs even in the absence of epicardial coronary artery disease when the coronary microcirculation is unable to supply the hypertrophied myocardium. In patients with HOCM, angina results from the elevated left ventricular systolic pressure. Pharmacologic management of hypotension in patients with HOCM should be done with volume replacement and vasoconstrictors rather than inotropes and vasodilators. (See page 1080: Hypertrophic Cardiomyopathy.) 20. What is the average prime volume for a cardiopulmonary bypass machine for adults? A. 500–1000 cc
B. 1500–2500 cc C. 3000–4000 cc D. 4000–4500 cc E. 5500–6500 cc 20. B. Many institutions use a standard volume prime for all adult patients, and others use a minimum volume based on body weight or body surface area. The average prime volume is 1500 to 2500 cc. (See page 1088: Prime.) 21. Which of the following statements regarding heparin is FALSE? A. Intravenous heparin's peak onset of action is less than 5 minutes. B. Heparin is a polyionic mucopolysaccharide. C. Heparin's half-life is approximately 90 minutes after intravenous (IV) injection. D. Hypothermia decreases the half-life of heparin. E. Heparin's anticoagulant effect is because of its ability to potentiate the antithrombin III activity. 21. D. Heparin is a polyionic mucopolysaccharide extracted from either bovine lung or porcine intestinal mucosa. After IV injection, the peak onset of heparin is less than 5 minutes with a half-life of approximately 90 minutes in normothermic patients. In hypothermic patients, there is a progressive increase in the half-life proportional to the degree of hypothermia. The anticoagulant effect of heparin is derived from its ability to potentiate the activity of antithrombin III. (See page 1088: Anticoagulation.) For questions 22 to 39, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 22. Which of the following volatile anesthetic(s) has/have the fastest recovery? 1. Desflurane 2. Isoflurane
3. Sevoflurane 4. Halothane 22. B. Desflurane and sevoflurane have the fastest recovery of all the volatile anesthetics. (See page 1076: Inhalation Anesthetics.) 23. Which of the following are adverse effects of sodium nitroprusside (SNP)? 1. Cyanide and thiocyanate toxicity 2. Rebound hypertension 3. Blood coagulation abnormalities 4. Hypothyroidism 23. E. SNP improves ventricular compliance in the ischemic myocardium. The recommended dose of SNP is 0.5 to 3 μg/kg/min and is reduced in the presence of hepatic or renal disease. Adverse effects include cyanide and thiocyanate toxicity, rebound hypertension, intracranial hypertension, blood coagulation abnormalities, increased pulmonary shunting, and hypothyroidism. (See page 1077: Sodium Nitroprusside.) 24. Which of the following are treatment options for cyanide toxicity? 1. Discontinuation of sodium nitroprusside (SNP) infusion 2. Administration of 100% oxygen 3. Administration of amyl nitrate (inhaler) 4. Administration of intravenous sodium nitrite 24. E. Cyanide is produced when SNP is metabolized. The presenting signs of cyanide toxicity include the triad of elevated mixed venous oxygen, requirements for increasing SNP dose, and metabolic acidosis. Treatment should consists of discontinuing the infusion, administering 100% oxygen, administering amyl nitrate (inhaler) or intravenous sodium nitrite and intravenous thiosulfate, except in patients with abnormal renal function, for whom hydroxocobalamin is recommended. (See page 1077: Sodium Nitroprusside.)
25. Nitroglycerin is a useful agent in the treatment of myocardial ischemia because it: 1. is a coronary arterial vasodilator 2. reduces venous return 3. may reverse acute coronary vasospasm 4. reduces heart rate via baroreceptor mechanisms 25. A. Nitroglycerin is a modest coronary arterial dilator and as such is the drug of choice for the acute treatment of coronary artery vasospasm. The reduction in venous return afforded by the venodilatory effect of nitroglycerin leads to a lessening in myocardial wall tension and thus to a reduction in myocardial oxygen demand. The use of nitroglycerin may result in reflex tachycardia caused by a sudden decrease in venous return. (See page 1077: Nitrates.) 26. A 48-year-old man with a history of severe hypertrophic cardiomyopathy (HCOM) is undergoing general anesthesia for elective total knee arthroplasty. A precipitous decrease in cardiac output is noted just before the skin incision. His vital signs include a blood pressure of 172/88 mm Hg and a heart rate of 104 bpm. Which of the following intervention(s) is/are most likely to improve cardiac output? 1. Administration of an inotropic agent 2. Administration of a volatile anesthetic agent 3. Titration of a vasodilator to decrease afterload 4. Administration of esmolol to decrease heart rate 26. C. The anesthetic management of patients with HCOM is directed at maintaining ventricular filling and minimizing the factors predisposing to variable outflow obstruction. In this case, the myocardial depression afforded by a volatile agent may be desirable, as would be a decrease in heart rate. Similarly, inotropic agents may compound the problem. Vasodilators do not improve the outflow obstruction and may result in precipitous decreases in systemic arterial pressures. (See page 1080: Hypertrophic Cardiomyopathy.) 27. Which of the following conditions may be associated with segmental wall motion abnormalities on transesophageal
echocardiography? 1. Myocardial ischemia 2. Hypovolemia 3. Myocardial infarction 4. Left bundle branch block 27. E. Segmental wall motion abnormalities are most commonly associated with myocardial ischemia or infarction. However, other conditions may also cause segmental wall motion abnormalities. Among these conditions are pacing, bundle branch blocks, myocarditis, tachycardia, and hypovolemia. In addition, nonischemic myocardium in proximity to ischemic or infarcted tissue may appear to have abnormal wall motion (“tethering phenomenon”). (See page 1075: Ischemia.) 28. Which of the following statements regarding stroke after coronary artery bypass graft surgery with is/are TRUE? 1. Stroke occurs in approximately 2% to 5% of patients. 2. Diabetes is an independent risk factor. 3. Excessive warming during and after cardiopulmonary bypass may increase the likelihood of its occurrence. 4. Stroke is most commonly the result of perioperative hypoperfusion injury. 28. A. The incidence of stroke after coronary artery bypass graft surgery is approximately 3%. They most commonly result from macroemboli. Patients of advanced age (>70 years) and those with diabetes, peripheral vascular disease, pre-existing cerebrovascular disease, history of stroke, or atheromatous plaque in the ascending aorta are at increased risk for postoperative stroke. In addition, operative factors such as prolonged duration of bypass and excessive rewarming during and after bypass increase the risk of neurologic complications. (See page 1102: Preoperative Evaluation: Central Nervous System Function and Complications.) 29. Physiologic effects of nitroglycerin include: 1. systemic venodilation
2. decreased afterload 3. coronary artery dilation 4. cyanide production 29. A. Nitroglycerin is a systemic venodilator. In addition, at higher doses, nitroglycerin dilates systemic arterial beds. Therefore, it both reduces preload (by decreasing venous return) and reduces afterload (by decreasing systemic arterial pressure). Nitroglycerin is the drug of choice in the treatment of patients with coronary vasospasm because it is also an effective dilator of the coronary arterial bed, including stenosed arteries and collateral beds. However, nitroglycerin may also cause methemoglobinemia, especially in patients with deficiencies of methemoglobin reductase. Sodium nitroprusside, not nitroglycerin, may produce cyanide and thiocyanate upon metabolism, posing the risk of toxicity during prolonged infusions or after administration of relatively large quantities over short time periods. (See page 1074: Coronary Artery Disease: Treatment of Ischemia.) 30. Pharmacologic agents with coronary artery dilator properties include: 1. nifedipine 2. nitroglycerin 3. diltiazem 4. magnesium 30. E. Nifedipine and diltiazem are calcium channel blockers that dilate coronary arteries and are used as antianginal agents in the prevention of coronary vasospasm. Nitroglycerin also has coronary artery dilating properties associated with the production of nitric oxide. Magnesium is another coronary artery vasodilator that has been used to reduce infarct size and minimize reperfusion injury in the setting of acute ischemia. (See page 1074: Coronary Artery Disease: Treatment of Ischemia.) P 31. Which of the following statements regarding cardiac valvular structure and pathology is/are TRUE? 1. The normal aortic valve is composed of three leaflets.
2. The normal mitral value consists of three leaflets. 3. Mitral valve stenosis is most commonly of rheumatic origin. 4. Chordae tendineae connected to the papillary muscles help prevent prolapse of the aortic valve leaflets into the left ventricle during systole. 31. B. The normal aortic valve consists of three leaflets, and the normal mitral valve is composed of two leaflets. Rheumatic fever is by far the most common cause of mitral stenosis. Chordae tendineae connected to the papillary muscles help prevent prolapse of the mitral valve leaflets. (See page 1078: Valvular Heart Disease.) 32. Mechanisms by which heparin exerts its anticoagulant effect include: 1. activation of factor XIIa 2. direct inhibition of factor II 3. inhibition of kallikrein 4. potentiation of antithrombin III 32. C. Heparin is a polyionic mucopolysaccharide extracted from bovine lung or porcine intestinal mucosa. Binding of heparin to antithrombin III greatly increases its intrinsic thrombin inhibitory properties, thereby preventing the formation of fibrinous clots. In addition, heparin binds directly to factor II (thrombin), thus inhibiting its action. Aprotinin is an antifibrinolytic agent and protease inhibitor that delays activation of the intrinsic coagulation cascade via inhibition of factor XIIa. In addition, it inhibits kallikrein and other serine proteases such as plasmin. It is used during cardiopulmonary bypass (CPB) to reduce blood loss, improve platelet function, and reduce the systemic inflammatory response to CPB. (See page 1086: Cardiopulmonary Bypass: Anticoagulation.) 33. Which of the following statements about cardiac tamponade is/are TRUE? 1. Clinical signs and symptoms include paradoxical pulse, tachycardia, and hypotension. 2. Stroke volume increases.
3. Cardiac output becomes rate dependent. 4. Compression of the left ventricle is usually most severe. 33. B. Cardiac tamponade involves an elevation in intrapericardial pressure, which impairs venous return and may cause cardiac chamber collapse. Under this circumstance, the chambers with the lowest intracardiac pressures (atria and right ventricle during diastole) are most at risk of collapse. Stroke volume in cardiac tamponade is relatively fixed, so cardiac output becomes dependent on heart rate. (See page 1102: Postoperative Considerations.) 34. Which of the following statements regarding the normal function of an intra-aortic balloon pump (IABP) is/are TRUE? 1. It is designed to reduce afterload. 2. It is designed to increase diastolic blood pressure. 3. A properly inserted IABP should have its distal tip just below the subclavian artery. 4. The balloon is designed to deflate during diastole. 34. A. The IABP uses a synchronized counterpulsation method to improve myocardial function by decreasing myocardial oxygen demand and increasing myocardial oxygen supply. The device is most commonly inserted into the femoral artery and advanced so the distal tip lies just below the subclavian artery and the proximal end is above the renal arteries. The balloon inflates during diastole, increasing aortic diastolic pressure and improving coronary perfusion as well as facilitating forward flow. During the subsequent systole, the balloon deflates, reducing systemic afterload and facilitating left ventricular ejection. (See page 1102: Preoperative Evaluation: Intra-aortic Balloon Pump.) 35. Techniques commonly used for perioperative blood conservation during cardiac surgery include: 1. red blood cell scavenging 2. perioperative administration of antifibrinolytic agents 3. intraoperative autologous hemodilution 4. nonpulsatile flow during cardiopulmonary bypass
35. A. Antifibrinolytic agents such as tranexamic acid, epsilonaminocaproic acid, and aprotinin have been shown to decrease blood loss in high-risk patients undergoing cardiac surgery. Such agents act to inhibit the fibrinolytic cascade triggered by the effects of extracorporeal circulation. Intraoperative hemodilution achieved by the removal of autologous blood provides a safe source of whole blood for reinfusion while being spared the damaging effects of the bypass circuit. (See page 1089: Blood Conservation in Cardiac Surgery.) 36. TRUE statements regarding intraoperative electrocardiographic monitoring include: 1. Lead II may be monitored to detect ischemia in the inferior wall of the left ventricle, as well as to assist in the detection of cardiac arrhythmias. 2. Lead V5 aids in the detection of ischemia to the anterior wall of the left ventricle. 3. Lead V5 is monitored to detect ischemia in regions of the myocardium supplied by the left anterior descending coronary artery. 4. Ischemia of the lateral wall of the left ventricle is detected by monitoring leads I and aVL. 36. E. Simultaneous monitoring of multiple electrocardiographic leads improves the sensitivity of ischemia detection while aiding in its localization. Leads II, III, and aVF are the most sensitive to ischemic changes in the inferior ventricular wall, typically supplied by the right coronary artery. Lead V5 is commonly used to monitor the anterior wall of the left ventricle (left anterior descending artery), and leads I and aVL provide the greatest information concerning the lateral left ventricular wall (left circumflex artery). (See page 1091: Monitoring.) 37. Relatively strong indications for the perioperative placement of a pulmonary artery catheter in a patient undergoing cardiac surgery include: 1. procedures in which continuous retrograde cardioplegia is to be used during cardiopulmonary bypass 2. a patient with moderate to severe pulmonary hypertension
3. access to central circulation for the infusion of vasoactive drugs 4. assistance in the management of a patient with impaired left ventricular function 37. C. Although indications for the placement of a pulmonary catheter vary among institutions, conditions in which left ventricular filling pressures cannot be reliably predicted by transduced right atrial pressures generally predicate pulmonary artery catheter placement. These conditions include pulmonary hypertension, left ventricular dysfunction or decreased compliance, and valvular dysfunction. Other indications include operations requiring prolonged operative time or combined procedures (valve replacement plus coronary grafting). (See page 1091: Monitoring.) 38. Examples of congenital cardiac lesions in which cyanosis develops as a result of obstruction to pulmonary flow include: 1. patent ductus arteriosus 2. ventricular septal defect 3. coarctation of the aorta 4. tetralogy of Fallot 38. D. In patients with tetralogy of Fallot, the right ventricular outflow obstruction may lead to cyanosis as a result of decreased pulmonary flow. The presence of a ventricular septal defect complicates the problem by providing a path of preferential flow in the setting of decreased systemic vascular resistance. Whereas ventricular septal defects and patent ductus arteriosus result in increased pulmonary blood flow from volume overload, coarctation of the aorta results in left ventricular pressure overload. (See page 1103: Table 41-21.) 39. Which of the following statements regarding amrinone and milrinone is/are TRUE? 1. They are phosphodiesterase inhibitors. 2. They increase myocardial contractility. 3. They decrease pulmonary vascular resistance.
4. They increase systemic vascular resistance. 39. A. Amrinone and milrinone are two drugs in a class of phosphodiesterase III inhibitors. These agents are very effective at decreasing pulmonary vascular resistance and increasing myocardial contractility. They are also systematic arterial vasodilators and therefore reduce left ventricular afterload, reducing myocardial work. (See page 1102: Preoperative Evaluation: Discontinuation of Cardiopulmonary Bypass.)
Chapter 42 Anesthesia for Vascular Surgery 1. The most effective medical therapy for atherosclerotic peripheral vascular disease is: A. dipyridamole B. urokinase C. warfarin (Coumadin) D. aspirin E. smoking cessation 1. E. Although antiplatelet medications such as aspirin may slow the progression of atherosclerosis and may be associated with cardiovascular events, cessation of smoking is by far the most effective form of medical therapy. This emphasizes the dramatic impact of tobacco abuse on the progression of atherosclerotic disease. Smoking cessation rates are approximately 25% after major surgery. Despite the low success rates, the benefits of smoking cessation are so great that such programs may be cost effective. Systemic anticoagulation and thrombolytic agents are generally reserved for cases of acute ischemia. (See page 1110: Medical Therapy for Atherosclerosis.) 2. In patients presenting for vascular surgery, the incidence of significant coronary artery disease (stenosis >70%) detected by angiography in patients without any clinical symptoms of coronary stenosis is approximately: A. 90%
2. C. Hertzer et al performed coronary angiography in 1000 consecutive patients slated to undergo vascular surgery and identified significant coronary artery stenosis (>70% occlusion) in 37% of patients who had no symptoms of coronary disease. These data indicate a high index of suspicion for coronary artery stenosis in patients presenting for vascular surgery even in the absence of a prior history of cardiac disease. (See page 1110: Coronary Artery Disease in Patients with Peripheral Vascular Disease.) 3. Most neurologic deficits after carotid endarterectomy are thought to result from: A. concomitant contralateral carotid stenosis B. prolonged carotid artery cross-clamp in the absence of shunt use C. thromboembolism D. perioperative vasospasm E. inadequate intraoperative carotid artery perfusion pressure 3. C. Although maintenance of adequate carotid artery perfusion pressure is an anesthetic goal during carotid endarterectomy, most studies indicate that as many as 65% to 95% of all neurologic deficits after carotid endartectomy may result from thromboembolic events. These may occur during surgical manipulation of the diseased vessel or in association with shunt placement. An embolism-related stroke rate of at least 0.7% has been reported in association with shunt placement, although no convincing data exist to indicate that routine shunt insertion reduces the incidence of postoperative neurologic deficits. (See page 1118: Monitoring and Preserving Neurologic Integrity.) 4. Each of the following are potential postoperative complications specific to carotid endarterectomy EXCEPT: A. hypertension B. bradycardia C. neurologic deficits D. respiratory insufficiency
E. renal insufficiency 4. E. Common problems arising after carotid endarterectomy include the onset of new neurologic dysfunction, hemodynamic instability during emergence from general anesthesia, and respiratory insufficiency. Blood pressure abnormalities are common after carotid endarterectomy; hypertension is more common than hypotension. Severe hypertension seems to occur more often in patients with poorly controlled preoperative hypertension. (See page 1117: Carotid Endarterectomy Postoperative Management.) 5. Distal ischemia as a consequence of aortic surgery generally results from: A. prolonged aortic occlusion B. inadequate distal runoff C. thrombosis resulting from inadequate anticoagulation D. postperfusion vasospasm E. atheroemboli 5. E. Although heparin is routinely administered before aortic occlusion to reduce the risk of thrombus formation, it is recognized that distal ischemic events after aortic surgery are generally the result of dislodgment of atheroemboli from the diseased aorta. It is believed by some that in the absence of major distal occlusive disease, systemic heparinization may be unnecessary when repairing abdominal aortic aneurysms. (See page 1127: Surgical Procedures for Aortic Reconstruction.) 6. The most important factor shown to be of clinical importance in preserving renal function during aortic cross-clamping is: A. lisinopril B. fenoldopam C. dopamine D. intravascular volume status E. mannitol
6. D. Renal protection is still a controversial topic, with no therapies proven to yield superior outcome. Many different methods of renal protection have been advocated, most of them centering on improving renal blood flow or glomerular flow. These include dopamine, fenoldopam, angiotensin-converting enzyme inhibitors, prostaglandins, vasodilators, isovolemic hemodilution, furosemide, and mannitol. Outcomes have not been shown to improve with any of these techniques. One of the most important factors for preventing postoperative renal failure remains good hydration (as the most important factor for maintaining renal blood flow) during clamping and post-clamp release. (See page 1125: Protecting the Spinal Cord and Visceral Organs.) For questions 7 to 17, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 7. Strategies that have been shown to reduce the incidence of myocardial ischemia in patients undergoing vascular surgery include: 1. treatment of tachycardia with β -adrenergic blocking agents 2. prevention of hypothermia 3. correction of anemia (hematocrit of Reproductive > Dermal > Nervous system B. Dermal > Gastrointestinal > Lymphoid > Reproductive > Nervous system C. Lymphoid > Reproductive > Gastrointestinal > Nervous system > Dermal D. Lymphoid > Dermal > Reproductive > Gastrointestinal > Nervous system E. Nervous system > Reproductive > Lymphoid > Dermal > Gastrointestinal 7. A. Tissue sensitivity to the effects of ionizing radiation varies based on cellular turnover rate. In general, tissue with the highest turnover rate is most affected by exposure to ionizing radiation. From greatest to least, sensitivity of human tissue to ionizing radiation is as follows: lymphoid > gastrointestinal > reproductive > dermal > nervous system. (See page 1565: Radiation Injury: Potential Sources of Ionizing Radiation Exposure.)
8. The influenza virus typically associated with pandemics, including P the Spanish flu of 1918, is of type: A. A B. B C. C D. D E. E 8. A. There were three large influenza pandemics in the twentieth century: one in 1918 during World War I, another in 1957 and 1958, and a third in 1968 and 1969. All of these pandemics were caused by antigenic shifts in the influenza type A virus. Major pandemics occur when a change in viral surface antigens occurs (antigenic shift) and naïve human hosts are exposed to a virus for which their immune systems have not made protective antibodies. Every year, influenza A vaccines are prepared in an attempt to predict the most likely combinations of viral surface antigens. However, because the behavior of the virus can be unpredictable, these vaccines are not 100% protective, and the risk of major outbreaks caused by unforeseen antigenic combinations is a persistent threat. (See page 1567: Biological Disasters: Epidemic: Influenza.) 9. Specific therapy for high-dose exposure to cyanide includes: A. sodium thiosulfate B. arsine C. pralidoxime chloride D. hyperbaric oxygen E. pyridostigmine 9. A. Cyanide ions are normally metabolized by the rhodanese liver enzyme in a sulfur-requiring step that leads to the formation of methemoglobin. In the setting of cyanide poisoning, sulfur stores are depleted, leading to enzymatic dysfunction. Treatment of cyanide poisoning therefore includes administration of sodium thiosulfate as a sulfur donor to regenerate enzymatic metabolism of cyanide ions. In the meantime, the patient may require tracheal intubation and mechanical
ventilation, sodium bicarbonate to treat metabolic acidosis, and inotropes and vasopressors for hemodynamic support. Arsine is one of the cyanogens that may cause cyanide toxicity, along with hydrogen cyanide, hydrocyanic acid, and cyanogen chloride. Hyperbaric oxygen may play a role in the management of carbon monoxide poisoning but is not indicated for cyanide poisoning. Pralidoxime chloride reactivates acetylcholinesterase and is used to counteract the muscarinic and nicotinic stimulant effects of nerve agents that inhibit acetylcholinesterase. Pyridostigmine is sometimes administered prophylactically in situations in which exposure to a nerve agent is anticipated because it binds to acetylcholinesterase and thereby protects it and allows for spontaneous enzyme regeneration. (See page 1572: Chemical: Blood Agents.) For questions 10 to 12, choose A if 1, 2, and 3 are correct; B if 1 and 3 are correct; C if 2 and 4 are correct; D if 4 is correct; or E if all are correct. 10. Which of the following statements regarding potential biological agents of terrorism is/are TRUE? 1. Smallpox transmission occurs mostly through aerosolized droplets. 2. The antibiotic treatment of choice for plague caused by Yersinia pestis is streptomycin. 3. Bacillus anthracis is a gram-positive, spore-forming bacillus. 4. Francisella tularensis infection may present as a skin ulceration. 10. E. Several types of biological agents carry the potential to be used as agents of terrorism. Smallpox is a highly infective virus that is most commonly transmitted via aerosolized droplets. Infection causes a prodrome of malaise, headache, and backache followed by the onset of high fever. As the fever subsides, smallpox lesions of multiple stages appear and are often particularly prominent on the face and distal extremities. Although it is infrequently fatal, smallpox is considered a biological threat because of its high infectivity and ability to cause significant and rapid morbidity. B. anthracis is a gram-positive sporeforming bacterium that causes three main types of infection: cutaneous,
inhalation, and gastrointestinal. Anthrax spores are extremely resistant to destruction and may survive dormant in the soil for years. Inhalational anthrax is the most lethal form of infection, although it is far less common than the cutaneous form. In addition to supportive care, treatment should include ciprofloxacin or doxycycline. Y. pestis is a gram-positive bacillus that causes plague. The treatment of choice is streptomycin, but chloramphenicol and tetracycline may also be used. F. tularemia is a gram-negative rod that may be contracted by humans via direct contact with an infected animal (most common), ingestion of infected food, or inhalation of aerosolized bacteria. The bacteria invade the body via hair follicles or microabrasions of the skin. At the site of entry, swelling becomes visible, followed by the development of a necrotic ulcer with a black eschar. Alternatively, inhalation of tularemia may lead to the development of pneumonia. As with anthrax and plague, the treatment of tularemia includes streptomycin antibiotic therapy. (See page 1567: Biological Disasters: Biological Terrorism.) 11. Which of the following is/are a unit used to measure radiation exposure? 1. Roentgen-equivalent-man (rem) 2. Sievert (Sv) 3. Gray (Gy) 4. Radiation absorbed dose (rad) 11. E. All of the units listed are measures of radiation exposure. Gray is the International System unit of measurement for the energy deposited by any type of radiation in joules per kilogram. Radiation absorbed dose also refers to the amount of energy deposited by any type of radiation to any tissue or other material, where 1 rad = 0.01 Gray. Roentgenequivalent-man and sievert are used to quantify human exposure to radiation. The sievert is part of the International System of units and, like the gray, is measured in joules per kilogram. One sievert (1 Sv) is equivalent to 100 rem. (See page 1565: Radiation Injury: Potential Sources of Ionizing Radiation Exposure and page 1566: Table 60-7: Types of Radiation.) 12. Which of the following is/are a category A biological agent(s)?
1. Variola major 2. Clostridium botulinum 3. Bacillus anthracis 4. Vibrio cholerae 12. A. Potential biological agents of warfare are classified into three categories based on degree of threat to national security: categories A, B, and C. Category A agents have the greatest potential to cause harm as a result of relative ease of transmission and high mortality. Bacillus anthracis (anthrax), Variola major (smallpox), Yersinia pestis (plague), Clostridium botulinum (botulism), Francisella tularensis (tularemia), and the viruses that cause hemorrhagic fever (Ebola, Lassa, Marburg, Argentine) are the six agents currently listed in category A. Vibrio cholerae (cholera) is a category B agent. (See page 1567: Biological Disasters; and page 1569: Table 60-9: Biological Agents Used for Warfare.)
