[Blood pressure control with an inhalation anesthetic in acute intraoperative hypertension. Hemodynamic profile of halothane, enflurane and isoflurane in coronary surgery patients].

The haemodynamic effects of isoflurane, halothane and enflurane when used to control intraoperative hypertension were evaluated in 30 patients undergoing coronary artery bypass grafting. The patients were anaesthetized with flunitrazepam, fentanyl, pancuronium and N2O-O2. Control measurements were made after skin incision. When mean arterial pressure increased to 110 mmHg due to sternal spread or surgical manipulation of the aorta, halothane, enflurane or isoflurane were administered to return arterial pressure to control levels. Using a non-rebreathing system, inspired halothane concentrations of 1.0-1.5 vol.%, enflurane concentrations of 2.0-2.5 vol.% and isoflurane concentrations of 1.5-2.0 vol.% were necessary. Measurements were repeated during the hypertensive episodes and after treatment with halothane, enflurane or isoflurane while surgical stimulation continued. During the hypertensive episodes marked elevations in systemic vascular resistance were observed, four patients developed ischaemic ST-segment changes. Each of the three inhalational anaesthetics decreased mean arterial pressure to baseline values within 5 to 10 minutes. The fall in blood pressure caused by halothane was mainly due to a reduction in cardiac index, since the elevated systemic vascular resistance almost remained unaffected. Enflurane produced a similar fall in cardiac index, although left ventricular afterload was significantly reduced, suggesting that enflurane caused more impairment of cardiac performance than halothane. In contrast, the administration of isoflurane was associated with an increase of the cardiac index in the presence of marked systemic vasodilation and a slight decrease in left ventricular filling pressure. Halothane, enflurane and isoflurane reduced the rate-pressure product by a comparable degree and, when present, abnormalities in the ST-segments disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)