HEMODYNAMIC AND CATECHOLAMINE RESPONSE TO ISOFLURANE ANESTHESIA IN PATIENTS UNDERGOING CORONARY-ARTERY SURGERY

Hemodynamic and plasma catecholamine responses were evaluated during isoflurane anesthesia in 10 patients undergoing coronary artery bypass surgery. Following thiopentone induction, the patients were anesthetized with isoflurane 1.5-2.0% in O2. After 10 min of isoflurane anesthesia there was a significant increase from baseline in heart rate 68 to 80; cardiac output, 3.75 to 4.61; and plasma epinephrine, 0.80 to 1.33 .mu.g/l. There was a significant reduction in systemic vascular resistance index, 3388 to 2260, and plasma norepinephrine, 1.10 to 0.88 .mu.g/l. Twenty-five min later after sternotomy, heart rate, cardiac output and the level of plasma epinephrine were still elevated, and systemic vascular resistance index and plasma norepinephrine remained lowered (P < 0.05). This study demonstrates significant catecholamine responses during isoflurane anesthesia. The increase in plasma epinephrine paralleled the increase in heart rate and cardiac output, and the decrease in plasma norepinephrine paralleled the decrease in systemic vascular resistance. Catecholamine responses evidently contribute to the cardiac and peripheral cardiovascular changes observed with isoflurane anesthesia.