A 65-year-old 75 kg man with transient cerebral attacks is to undergo carotid endarterectomy. He has hypertension treated with alphamethyldopa, and experiences angina pectoris for which he takes propranolol 160 mg/day. He has a 40-pack year smoking history and coughs repetitively during your examination. Blood pressure is 165/95 mmHg, pulse is 64 bpm, respirations are 14, and hemoglobin is 15.
I. Circulatory status - evaluation of cardiac function
1. Does the history of angina result in unusual risk to anesthesia and this surgery? Explain.
2. Is additional workup needed?
3. What tests do you want? Explain.
4. How would you manage his preoperative cardiovascular drugs? Explain your rationale.
5. How do nitrates cause antianginal effects?
Beneficial antianginal effects are a result of platelet effects, reducing myocardial demand, and increasing coronary perfusion. Nitric oxide inhibits platelet aggregation, venodilation decreases venous return and thus decreases left ventricular filling pressures, wall tension, and myocardial oxygen demand. Coronary spasm is relieved, and epicardial coronaries, collaterals, and stenotic segments dilate.
II. Assessment of cerebral blood flow
1. What is the significance of transient ischemic attacks?
2. Discuss cerebral vs cardiac etiologies.
3. How will you assess this patient preoperatively?
4. What significant findings would influence anesthesia care?
III. Assessment of pulmonary status
1. How would you differentiate between bronchitis and emphysema?
2. What is the importance of making this distinction?
3. What further clinical and laboratory pulmonary studies do you want? Discuss your rationale for each.
4. What is their importance to anesthesia care?
I. Selection and interpretation of data from monitors
1. Should an arterial line be placed? Explain.
2. You fail in your attempt to place a radial line. Would you attempt an ulnar site?
3. What other sites would you attempt?
4. What are other sites as alternatives?
5. Discuss the circumstances in which a pulmonary artery catheter should be placed.
6. What methods would you to use to assess cerebral perfusion. Explain your rationale.
II. Choice of anesthesia
1. Is regional anesthesia preferable to general anesthesia? Explain.
2. You choose general anesthesia. How will you manage the patient?
3. What is your rationale for drug selection?
4. Compare circulatory and cerebral effects of importance to this patient.
III. Management of breathing
1. Discuss spontaneous vs controlled ventilation.
2. Discuss which one you would choose, and explain your rationale.
3. Breathing occurs during carotid cross-clamping, whereas it was controlled immediately prior to this. What are the possible causes?
4. What is your treatment?
I. Failure to arouse
1. The patient is unresponsive 45 minutes postoperatively. Is this due to effects of residual anesthesia? Explain.
2. What other causes might be involved?
3. How will you establish the cause?
4. Discuss your management.
II. Pulmonary aspiration
1. The patient regurgitates during extubation. Now he is wheezing. What is your differential diagnosis?
2. How will you establish a diagnosis?
3. What is your immediate diagnosis?
4. The paO2 is 60 mmHg on an FIO2 of 50%. What are your next steps? Explain your rationale.