Hemodynamic and hormonal changes in patients pretreated with captopril for surgery of the abdominal aorta

Cardiovascular and hormonal responses to aortic cross-clamping (ACC) and declamping (ADC) were studied in 20 patients undergoing reconstructive aortic surgery anesthetized with fentanyl and droperidol. Ten of the patients served as a control group, and 10 patients were treated with oral captopril (25 mg the day before operation and 25 mg one hour before anesthesia) to prevent intraoperative and postoperative hypertension. After the induction of anesthesia in the captopril group, hypotension was seen in four patients and bradycardia in three patients. In both groups, the most important changes in hemodynamics after the ACC were an increase in systemic vascular resistance and decreases in cardiac and stroke index. After the ADC, the cardiac index (CI) improved nearly to the level before the ACC. The urine output during anesthesia was 46 +/- 5 mL/h in the control group and 73 +/- 11 mL/h (P less than 0.05) in the captopril group. Postoperatively, patients in both groups were hypertensive and tachycardic. In the control group, plasma renin activity rose significantly during the ACC, indicating activation of the renin-angiotensin system (RAS). In both groups, significant increases in plasma vasopressin (PAVP), epinephrine, and norepinephrine were also observed before the ACC and during the postoperative period. The results suggest that oral captopril increases the risk of hypotension and bradycardia after induction of anesthesia, and does not prevent postoperative hypertension.