A 65-year old 55 kg woman with known mitral stenosis enters your emergency ward with small bowel obstruction. She is to go for an exploratory laparotomy. She is on daily digoxin and furosemide. On preoperative exam, she is clearly dyspenic and has a very distended abdomen. Blood pressure is 100/50 mmHg, pulse is 110 bpm, respirations are 30, hematocrit is 25, and a blood gas shows pH=7.20, paCO2 = 38 mmHg, and paO2 of 50 mmHg. Sodium is 130 mEq/l, and potassium is 2.5 mEq/l. Electrocardiogram shows atrial fibrillation.
I. Fluid status
1. How would you evaluate this patient's state of hydration?
2. What are the goals of your preoperative fluid management?
3. Describe the body water composition of a 70 kg man.
Total body water is about 60% of the ideal body weight, or 42 liters. Of this, 60% is intracellular and 40% is extracellular.
II. Cardiac status
1. How would you assess the adequacy of digitalization?
2. Would a serum digoxin level be helpful?
3. What is the significance of the potassium level?
III. Pulmonary status
I. Monitoring technique
1. What special monitors will you use in this patient? Explain.
2. What are general complications of pulmonary artery catheterization?
Complications include carotid puncture, infection, bleeding, coiling in the right ventricle, knot formation, failure to wedge, pulmonary artery perforation, venous air embolism, arrhythmias including right bundle branch block and complete heart block, infection, and mismanagement of spurious data.
2. Are there particular hazards to pulmonary artery catheterization in this patient? Explain.
3. How would you prevent these complications?
4. The surgeon asks you to monitor V5 lead. Is this appropriate?
II. Choice of anesthetic technique
1. Would you recommend regional or general anesthesia? Explain.
2 What regional technique would you choose? Explain your rationale.
3. What drugs would you choose? Explain.
4. What are the cardiovascular effects of these drugs?
III. Complication during induction
1. The patient demands general anesthesia. What is your response?
2. Despite precautions, you see feculent vomiting pouring into her trachea during laryngoscopy. What is your management?
3. Would pretreatment with an antacid have been helpful?
4. Would pretreatment with an H2 blocker have been helpful?
5. Would pretreatment with an H1 blocker have been helpful?
IV. Intraoperative tachycardia
1. Suppose no pulmonary aspiration occurred. One hour after induction, she develops a supraventricular tachycardia with a ventricular rate of 150 bpm. What is the hemodynamic significance of this?
2. What is your treatment?
3. What is your rationale for therapy?
I. Ventilatory Management
1. What criteria would you use for mechanically ventilating the patient postoperatively?
2. She has a blood gas that shows a paO2 of 40 mmHg on an FIO2 of 40%. What will you do?
3. What are the hazards of positive end-expiratory pressure?
4. How would you wean?
1. The patient begins shaking upon arrival to the recovery room. What is your differential diagnosis?
2. Will shivering occur if the body core temperature is 37 degrees centigrade?
3. What is the mechanism?
4. What are the risks of shivering?
5. What is the treatment?
6. What drugs can you give?
7. What rewarming methods would you use?