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Anesthesia HQ

Case Scenarios

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Anesthesia HQ: Case Scenarios!

©ANESTHESIA HQ 2009! 1

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" Anesthesia HQ: Case Scenarios

2! ©ANESTHESIA HQ 2009

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Preface

My motivation in creating Anesthesia HQ was to create a concise and comprehensive anesthesia study guide and an interactive web site for those preparing for the anesthesia board exams. During the past several years, I!ve had the opportunity to assist many examinees prepare and pass their anesthesia board exams. It is with feedback and critical input from many that I am able to continue to improve the board preparation materials and the web site. This fifth edition (2009) of the Anesthesia HQ: Case Scenarios study guide maintains my initial goal and with the combination of the website, www.anesthesiahq.com, offers a unique learning experience for those preparing for the anesthesia board exams.

The study guide is organized in an easy to read format, which also will provide you with the opportunity to add your own knowledge, thoughts, and comments throughout the review process. The study guide is intended as a supplement and an aid to your previous years of study, diligence, and hard work. From the moment you begin preparing for the anesthesia board exam, you should read, reread, and review again, all of the topics and information contained in the study guide, web site, and additional textbooks.

My goal is to provide you with the tools to prepare, organize, and ultimately pass the anesthesia board exams. I wish you good luck and success in your studies and career.

Michael K Loushin, MDFounderAnesthesia HQ



http://www.ANESTHESIAHQ.com

http://www.ANESTHESIAHQ.com

Notice

The information contained herein is only to be used as a study aide in preparation for the anesthesia board exams. Such information is not to replace any medical education, clinical experiences, or the study of textbooks and medical journals. The actual use of this information, including any medical concepts, facts, drug dosages, and methods, therefore is at the reader!s own risk. We assume NO responsibility for any injury or damages to any person or property that may result from such reliance on or use of any of this information.

We have taken all reasonable precautions to confirm the accuracy of the information presented herein and to describe generally accepted practices. However, we are not responsible for any inaccuracies, errors, and/or omissions or for any consequences from the use or application of any of the information contained herein and make no promise or warranty, express or implied, with respect thereto.

We have taken all reasonable precautions to ensure that the drug selection and dosages set forth in this text are in accordance with recommendations and practice current at the time of writing. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is solely responsible for reviewing and following the package insert for each drug for any change in indications and dosage and for any warnings and precautions. This is particularly important when the recommended agent is a new or infrequently employed drug.

Some drugs and medical devices presented in this publication have Food and Drug Administration (FDA) clearance for limited use in restricted research settings. It therefore is the sole responsibility of the reader to ensure that the applicable health care provider has ascertained the FDA status of each drug or device planned for use in their clinical practice.

THE READER ASSUMES ANY AND ALL RISKS ASSOCIATED WITH THE ACTUAL USE AND/OR RELIANCE ON ANY OF THE INFORMATION CONTAINED HEREIN THAT DEVIATES IN ANY WAY FROM THE INTENDED PURPOSE OF SUCH INFORMATION AS ONLY A STUDY AIDE IN PREPARATION OF THE ANESTHESIA BOARD EXAMS. TO THE EXTENT THE READER ULTIMATELY RELIES ON AND/OR OTHERWISE USES ANY SUCH INFORMATION FOR ANY OTHER PURPOSE, WHETHER INTENDED OR OTHERWISE, THE READER AGREES TO INDEMNIFY AND HOLD US HARMLESS FROM ANY AND ALL INJURIES, DAMAGES, COSTS, FEES AND EXPENSES (INCLUDING ATTORNEYS! FEES AND EXPENSES) THAT MAY OR DOES IN ANY WAY RESULT FROM SUCH ACTUAL USE AND/OR RELIANCE.



Table of Contents

How to Use the Anesthesia HQ: Case Scenarios" 7

Welcome to the Anesthesiology Oral Board Exam" 9

Rules of the Game" 11

Scoring the Exam" 13

The Stem" 15

Outlining the Stem Question" 17

Things to consider as you outline the stem" 18

Critical Events" 25

Aspiration" 26

Hypoxemia" 27

Hypertension" 28

Laryngospasm" 29

Bronchospasm" 30

Anaphylaxis" 31

Hypotension" 32

Increased peak airway pressure" 33

Hypercarbia" 34

Dysrhythmias" 35

Oliguria" 36

Delayed Emergence and Agitation in PACU" 37

Have plan B when plan A fails" 38

I don!t do hearts. Next question please." 39

When a difficult airway becomes more difficult" 40

Case Scenario: Acoustic Neuroma" 41

Examinee!s Response: Acoustic Neuroma" 47

Case Scenario: Mediastinoscopy & Lobectomy " 57

Examinee!s Response: Mediastinoscopy & Lobectomy " 63

Case Scenario: Abdominal Aortic Aneurysm" 73

Examinee!s Response: Abdominal Aortic Aneurysm" 81

Case Scenario: Inguinal Hernia" 97

Examinee!s Response: Inguinal Hernia" 103

Case Scenario: Sinus Surgery " 115

Examinee!s Response: Sinus Surgery " 121

Case Scenario: Cholecystectomy " 133

Examinee!s Response: Cholecystectomy " 141



Case Scenario: Bone Marrow Transplant" 153

Examinee!s Response: Bone Marrow Transplant" 161

Case Scenario: Gastric Bypass" 173

Examinee!s Response: Gastric Bypass" 181

Case Scenario: Seizure Disorder" 195

Examinee!s Response: Seizure Disorder" 203

Case Scenario: 23 Weeks Pregnant" 215

Examinee!s Response: 23 Weeks Pregnant" 223

Case Scenario: Laparoscopic Nephrectomy " 235

Examinee!s Response: Laparoscopic Nephrectomy " 241

Case Scenario: Exploratory Laparotomy " 251

Examinee!s Response: Exploratory Laparotomy " 255



How to Use the Anesthesia HQ: Case Scenarios

The Anesthesia HQ: Case Scenarios study guide contains twelve case scenarios. Each case scenario is followed by a series of examiner!s questions. The examiner!s questions are followed by an examinee!s responses. The responses are in a format to provide the thought process of the examinee. It is designed to provide a realistic examiner–examinee interaction during an oral board exam. Your answers, anesthetic management, and assessment of clinical situation may be different from the examinee!s responses in this study guide.

Each case scenario (stem) presents medical information about the patient whom you are required to anesthetize. Some stems will provide all the necessary preoperative information; others contain limited preoperative information.

To prepare and organize your thoughts, you must develop an outlining technique. As you begin this process, allow yourself plenty of time to outline. Eventually, you will need to limit your outlining time to about 10 minutes, which is the approximate length of time you will have during the actual oral board exam.

Practice your responses out loud. By practicing out loud to yourself, you will be forced to listen to how you actually sound instead of how you think you sound. It!s also useful to record yourself and complete multiple mock orals with other board certified anesthesiologists.

At the end of the questions are the examinee!s responses. The responses may be different from your responses, but that is expected. There are many different ways to answer the questions, just as there are different ways to do an anesthetic for a particular surgery.

Prepare as best you can and then go with confidence that you will pass the oral board exam. In the end, your hard work, discipline, and dedication should help you obtain the distinguished honor of being a diplomat of the American Board of Anesthesiology.



Case Scenario: 23 Weeks Pregnant

A 22-year-old female is 23 weeks pregnant. She is scheduled for an appendectomy. Vitals: P 65; BP 125/78; R 22; Temp 36.5º C; Hgb 10; K+ 3.2.

This case scenario discusses the preoperative and intraoperative events. Additional topics are also discussed after the main case scenario.

Anesthesia HQ: Case Scenarios! 23 Weeks Pregnant


23 Weeks Pregnant! Anesthesia HQ: Case Scenarios

216" ©ANESTHESIA HQ 2009

Pre-Operative Management

1. Is the hemoglobin of 10 normal for a pregnant woman?

2. Why is the hemoglobin lower in a pregnant woman?

3. What happens to the plasma volume during pregnancy? Explain the cardiac changes during pregnancy.

4. When do most of the physiologic changes of pregnancy occur?

5. How long do these changes last after pregnancy?

6. How is respiratory function altered during pregnancy?

7. Does pregnancy have any effect on liver function?

8. What happens to plasma cholinesterase during pregnancy?

9. How is kidney function affected during pregnancy?

10. The patient asks if anesthesia is going to hurt her baby. How will you respond?

11. Are you going to consult the obstetric service prior to surgery?

12. How about the neonatologist?

13. Is the fetus viable at this age?

14. At what age is a fetus viable?

15. How does anesthesia affect uterine perfusion?

16. The mother wonders how you will know if the baby is doing okay during surgery. How will you respond?

17. The patient is quite nervous. Is midazolam an appropriate choice for sedation?

18. What other sedative could you use?

19. Would you hydrate the patient in the preoperative area?

20. Are you going to give any medications for reflux prophylaxis? Which medication and what dose?

21. Are you going to monitor fetal heart tones during the case?

22. At what stage of pregnancy would you consider fetal heart monitoring?

23. How will you monitor fetal heart tones?



24. What is a normal heart rate for a fetus?

25. What is a fetal heart tone deceleration?

26. What are the types of decelerations? What!s the significance of decelerations? How will you treat the decelerations?

27. Can an abdominal surgery trigger uterine contractions?

28. Are you going to use uterine contraction monitor?

Intra-Operative Management

1. What ECG leads will you monitor?

2. You notice an inversion of the T-wave in lead II and left axis deviation. What is your interpretation?

3. Can you place the blood pressure cuff on the patient!s forearm? Is a forearm blood pressure accurate?

4. The patient!s heart rate is 100. Do you want to treat it?

5. The patient needs to be supine for the surgery. Is this an appropriate position?

6. Will tilting the table achieve the same effect as a bump under the patient!s right side?

7. Are you going to use a precordial stethoscope?

8. Where are you going to place it?

9. Can you detect right mainstem intubation with a precordial stethoscope? How is this possible?

10. What is your choice for anesthesia?

11. Can you do this case with a spinal anesthetic?

12. How does a spinal anesthetic affect uterine perfusion?

13. What drug will you use for the spinal?

14. Should the spinal anesthetic dose be altered for a pregnant patient?

15. Are you going to give a test dose containing epinephrine?

16. You decide to proceed with general anesthesia. What airway changes occur during pregnancy?



17. When do airway changes begin?

18. How long after delivery of the fetus do airway changes last?

19. What airway equipment will you need and use?

20. Can you use an LMA for this case?

21. Is a rapid sequence induction required?

22. Can muscle relaxants cross the placenta?

23. Which induction drug would you use?

24. Is drug dosing affected by pregnancy?

25. Is it reasonable to use propofol?

26. Would you consider ketamine?

27. Is sevoflurane appropriate for maintenance of anesthesia?

28. Some would say isoflurane is better than sevoflurane. How will you respond to this comment?

29. Is MAC affected by pregnancy?

30. The patient is requiring more anesthesia. Would you supplement with nitrous oxide? Should you avoid nitrous oxide during pregnancy?

31. What is the best muscle relaxant for this case?

32. The surgeon states that you should use a continuous infusion of succinylcholine. How will you respond?

33. Five minutes after incision, the patient becomes tachycardic. Her heart rate is 124; she also displays facial and truncal flushing. What is your differential diagnosis and treatment option?

34. Will you administer narcotics or beta blockers?

35. Do beta blockers cross the placenta?

36. Do narcotics affect the fetus?

37. What alterations in fetal heart tones are expected after administration of opioids to the mother?

38. Does fluid status affect fetal heart tones? Explain aorto-caval compression syndrome.

39. When will you extubate this patient? What are the criteria for extubation?



40. The patient complains of nausea and begins vomiting shortly after extubation. How will you manage now?

41. Is ondansetron safe during pregnancy?

42. How will you rule out aspiration? Oxygen saturations are in the low 90s. Would you order a chest x-ray?

43. You decide that the patient did aspirate. How will you proceed?

44. The patient complains of abdominal pain and cramps. The patient wonders if this could be uterine contractions. How would you respond?

45. What is your treatment plan?

46. The patient starts shivering. How much meperidine would you administer?

47. Can you use meperidine for pain control?

48. Would you treat severe nausea and vomiting with droperidol?

Additional Topics

1.! Pacemakers

a.! A 57 year-old man is scheduled for a laparoscopic cholecystectomy. The patient has a pacemaker which was placed for heart block. He also has a history of congestive heart failure, which is currently stable. You are waiting for an electrophysiology nurse to interrogate the pacemaker. The patient is unable to provide any information about the pacemaker"s mode, rate, model, and programming. The surgeon insists on proceeding to the operating room without interrogating the pacemaker. Will you proceed to the operating room? What particular information about the pacemaker do you want to know prior to surgery?

b.! The pacemaker is in DDD mode with a rate of 80. What does this mean? Is this an mode appropriate for surgery?

c.! What mode would you want?

d.! Can muscle twitching from succinylcholine affect pacemaker function?

e.! What is sequential pacing?

f.! Will a bipolar cautery affect the pacemaker?



2.! Equipment – automated blood pressure

a.! Is the blood pressure from an automated blood pressure cuff more or less accurate than an invasive arterial-line?

b.! Explain how the automated blood pressure cuff works.

c.! What if the size of the cuff is inappropriate for the particular patient?

d.! Is the blood pressure reading affected by arrhythmias such as atrial fibrillation?

e.! What is damping on an arterial waveform?

f.! What is the purpose of the transducer “flush” test?

There is a knock on the door, and the exam is over.

!



Examinee!s Response:

23 Weeks Pregnant

Examinee’s Response

Pre-Operative Management1.! Is the hemoglobin of 10 normal for a pregnant woman?

During the second and third trimester, pregnant women develop dilutional anemia. The plasma volume increases and dilutes the hemoglobin concentration. A hemoglobin concentration of 10 is normal.

2.! Why is the hemoglobin lower in a pregnant woman?

A dilutional anemia develops as the intravascular volume increases during pregnancy.

3.! What happens to the plasma volume during pregnancy? Explain the cardiac changes during pregnancy.

Plasma volume increases during pregnancy. As the pregnancy progresses, heart rate and cardiac output increase. Cardiac output can increase by 100% by the time delivery of the fetus occurs. Intravascular volume also increases. Systemic vascular resistance normally decreases during pregnancy.

4.! When do most of the physiologic changes of pregnancy occur?

The majority of the cardiac changes occur during the final trimester. Cardiac output and plasma volume are significantly increased. Cardiac output nearly doubles during labor from normal.

5.! How long do these changes last after pregnancy?

The cardiac alterations during pregnancy begin to return to normal immediately after delivery. The intravascular volume decreases; heart rate and cardiac output decrease immediately after delivery.

6.! How is respiratory function altered during pregnancy?

As the fetus grows, the uterus displaces the abdominal contents and diaphragm more cephalad. Functional residual capacity (FRC) decreases. The decrease in FRC results in less oxygen reserve. The tidal volumes also become smaller during pregnancy. Even though the tidal volume is smaller, minute ventilation increases during pregnancy. Pregnant patients are prone to faster desaturation due to decreased oxygen reserve and increased metabolic requirement of oxygen.

7.! Does pregnancy have any effect on liver function?

Pregnancy can alter liver function, especially if a female develops symptoms of pre-eclampsia and HELLP syndrome. HELLP syndrome is hemolysis, elevated liver enzymes,



and low platelets. If pre-eclampsia develops, the pregnant patient is also at increased risk of coagulopathy. Usually, liver function is normal during pregnancy.

8.! What happens to plasma cholinesterase during pregnancy?

Plasma cholinesterase concentration decreases during pregnancy. The plasma cholinesterase concentration is lower due to plasma dilution. The plasma cholinesterase still has normal function and does not significantly alter its effect on metabolizing drugs such as succinylcholine.

9.! How is kidney function affected during pregnancy?

Kidney function is normal during pregnancy. Due to the increased plasma volume and elevated cardiac output, urine production is increased. If pre-eclampsia develops, renal dysfunction can occur.

10.!The patient asks if anesthesia is going to hurt her baby. How will you respond?

All of the medications that the mother receives can potentially affect the baby. A majority of the common anesthesia medications should not have any adverse effects on the baby. Although unlikely to occur, no matter what anesthesia technique is used, there is an increased risk of spontaneous abortion and premature labor. I will reassure the mother that all appropriate monitors will be used prior to surgery and immediately after surgery in the post-operative care unit. I will also inform the mother that, immediately after surgery, she may notice decreased activity by the baby. Anesthetics and opioids will make the baby inactive, which is a normal side effect of the medications. I will again reassure the patient that I will keep things as safe as possible for both her and her baby.

11.! Are you going to consult the obstetric service prior to surgery?

I will inform the obstetrics team prior to surgery. They will need to help monitor the mother and fetus during the perioperative period.

12.!How about the neonatologist?

I don!t believe a neonatologist needs to be involved on this case at this time but should be made aware of the patient. If any evidence of premature labor occurred, then it would be appropriate to involve the neonatologist. Obviously, the obstetrician must be informed of any premature labor.

13.!Is the fetus viable at this age?

At 23 weeks the fetus is very unlikely to be viable. However, in rare instances, a fetus this young could survive with extreme medical care.

14.!At what age is a fetus viable?

With advances in medicine, a fetus is viable around 26-28 weeks.

15.!How does anesthesia affect uterine perfusion?

Uterine perfusion is dependent upon mean arterial pressure and uterine artery pressure. General anesthesia can decrease preload and blood pressure, which subsequently would decrease uterine blood flow. Placing the patient in a left uterine displacement position will increase uterine blood flow.



16.!The mother wonders how you will know if the baby is doing okay during surgery. How will you respond?

The best way to know that the baby is doing fine during surgery is to know that the mother is doing well. If the mother!s vital signs are normal, then the baby should be doing okay. One could monitor fetal heart tones during surgery, but spot checks of heart tones are usually adequate.

17.!The patient is quite nervous. Is midazolam an appropriate choice for sedation?

Midazolam is not an appropriate choice for pregnant women. It has a small risk of causing some birth defects. I would explain the risk of midazolam to the patient. It!s best to calm her anxiety about surgery by talking with her.

18.!What other sedative could you use?

The best sedative is to reassure the mother that it!s okay to be nervous and that we will keep things as safe as possible. Although not a true sedative, IV fentanyl may help.

19.!Would you hydrate the patient in the preoperative area?

Intravascular hydration is critical in pregnant women who are undergoing surgery. I would administer at least 500 mL of lactated ringer!s solution prior to the operating room. The intravascular volume needs to be normal in order to maintain uterine perfusion.

20.!Are you going to give any medications for reflux prophylaxis? Which medication and what dose?

Pregnant patients in their second and third trimester are at increased risk of gastric regurgitation and aspiration. The patient needs a non-particulate antacid such as Bicitra prior to surgery. She will also require a rapid sequence induction and intubation.

21.! Are you going to monitor fetal heart tones during the case?

After consulting with the obstetric service, I would follow their recommendations as to continuous or intermittent fetal heart tone monitoring. At our institution, we most often monitor the fetal heart tones just prior to surgery and in the post-operative period. The fetal heart tone monitoring is done by an obstetric nurse or an obstetrician.

22.!At what stage of pregnancy would you consider fetal heart monitoring?

Fetal heart tones should be monitored during the second and third trimester.

23.!How will you monitor fetal heart tones?

Again, I will not personally monitor fetal heart tones. That will be done by an obstetrician or an obstetric nurse.

24.!What is a normal heart rate for a fetus?

A normal heart rate for a fetus is 120-160 beats per minute.



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