A 64-year-old 72 kg man with advanced chronic obstructive pulmonary disease and insulin-dependent diabetes is scheduled for repair of an epigastric incisional hernia. He required mechanical ventilation for 6 weeks after a gastrectomy 4 months ago. Medications include aminophylline, cimetidine, and 20 U of NPH insulin each morning. Blood pressure is 220/110 mmHg, pulse is 84 bpm, respirations are 20, temperature is 37 degrees centigrade, and hematocrit is 42.
I. Pulmonary assessment
1. Considering his pulmonary disease, diabetes, and hypertension, which do you consider most important? Explain why.
2. Will you further evaluate his pulmonary function? Explain.
3. How will you further evaluate?
4. His FEV1 is 33% of predicted, vital capacity is 46% of predicted, and FEV1/FVC = 0.46. On room air, arterial blood gas shows paCO2 = 53 mmHg, paO2 = 46 mmHg, and HCO3 = 32 mEq/L. What is your interpretation?
5. Will you delay surgery? Explain.
6. What is your treatment?
7. Is he in optimum condition?
II. Status of diabetes
1. Fasting blood sugar is 300 mg/dl. Will you delay surgery? Explain.
2. How will you treat?
3. Under what conditions should one postpone the operation?
I. Choice of anesthetic agent
1. Would you use regional or general anesthesia? Explain.
2. What is the anticipated effect on pulmonary function for regional anesthesia?
3. Would you give a subarachnoid or an epidural block? Explain.
4. Which drugs would you choose? Explain.
5. What effect do local anesthetics have on the cardiovascular system?
6. Assume general anesthesia. Would you give by mask or endotracheal method? Explain.
7. What induction agent would you give? Explain.
8. Would you use muscle relaxant or deep inhalational anesthesia? Explain.
9. What is your choice of relaxants?
10. Give your rationale and monitoring methods.
1. Is capnography indicated? Explain, and include the mechanism of how the capnograph works.
The capnograph continually samples a small sample of gas from the anesthesia circuit, using infrared and mass spectrometry. A number and a wave-form are generated. This can be used to confirm endotracheal tube vs esophageal tube placement, and to correlate the value with alveolar and arterial CO2.
2. Do you want to visualize the waveform? Explain.
3. End-tidal CO2 increases from 42 to 50 mmHg in this patient, who is being mechanically ventilated. What is your differential diagnosis?
4. Is there a precise correlation with paCO2? Explain.
III. Management of blood loss and replacement
1. The spleen is injured during efforts to mobilize the abdominal wall. 500 ml and then another 500 ml blood loss occurs in successive 10-minute periods. What is your fluid management?
2. What are your blood and component requests? Give reasons.
3. What is your anesthetic management during this time?
I. Management of pulmonary status
1. Will you extubate this patient? Explain.
2. What are your criteria for extubation of this patient?
3. How will you manage mechanical ventilation?
4. How will you manage weaning?
5. The post extubation blood gas shows pH = 7.29, paCO2 = 66 mmHg, and paO2 = 73 mmHg on an FIO2 of 40%. Will you reintubate this patient?
6. Would you give supplemental oxygen?
7. What are the hazards associated with this?
II. Management of oliguria
1. The urine output is 10 ml/h. Are you concerned? Explain.
2. What is your differential diagnosis?
3. The central venous pressure is 20 mmHg and the urine specific gravity is 1.010. Is this acute tubular necrosis?
4. How would you confirm this diagnosis?
5. What are your next steps in management?