Circulatory effects of isoflurane in patients with ischemic heart disease: a comparison with halothane

The circulatory effects of isoflurane (I) were compared with those of halothane (H) in two groups of patients premedicated with morphine and scopolamine and scheduled for coronary artery bypass surgery. Both groups were similar with respect to age, weight, sex distribution, body surface area, left ventricular function, and preoperative dose of propranolol. While the patients were awake and breathing 100% oxygen, cardiac output and related hemodynamics were measured. The patients were then anesthetized by the same anesthesiologist with either isoflurane or halothane plus 50% N2O in O2. Ventilation was controlled to keep PaCO2 within the normal range. Hemodynamic measurements were repeated 10 min after intubation and during surgery 10 min after sternotomy. Heart rate did not change significantly in either group. Arterial blood pressure fell equally during anesthesia and returned toward baseline values during surgical stimulation in both groups. Cardiac output decreased in both groups during anesthesia and surgery. Cardiac output decreased significantly (P less than 0.05) more in the H group during surgery than in the I group. Systemic vascular resistance was significantly (P less than 0.05) lower in the I group during anesthesia and surgery. The manner and degree of maximum increases in arterial pressure and heart rate after intubation and the onset of surgical stimulation were similar in both groups.