Hemodynamic Effects of Anesthesia in Patients Chronically Treated With Angiotensin-Converting Enzyme Inhibitors

Angiotensin-converting enzyme inhibitors (ACEIs) are increasingly used in the treatment of cardiovascular disease, but recent reports have warned of some hemodynamic risk (hypotension and bradycardia) when associated with anesthesia. To assess the hemodynamic effects of induction of anesthesia in patients chronically treated with ACEIs, 16 hypertensive patients scheduled for coronary artery bypass graft surgery (n = 12) or vascular surgery (n = 4) were studied. Eight of them were chronically treated (for at least 1 mo) with ACEIs (ACEI group), and the remaining eight (control group) were treated with other classes of antihypertensive drugs. Induction of anesthesia, which consisted of flunitrazepam (0.03 mg/kg), fentanyl (0.006 mg/kg), and pancuronium (0.1 mg/kg) IV, was followed by a significant decrease in mean arterial blood pressure from baseline in both groups (by 16.8% in controls [P = 0.001] and 33.5% in ACEI-treated patients [P = 0.001] [P = 0.041 between groups]). In control patients, mean arterial blood pressure decrease was only associated with a significant decrease in cardiac index (−18%, P = 0.014). In ACEI-treated patients, the arterial blood pressure decreases were associated with consistent reductions in pulmonary capillary wedge pressure (−26.4%; P = 0.035) and cardiac index (−23.9%; P = 0.001). Systemic vascular resistance index and heart rate were moderately changed (−14.2% and −4.5%, respectively). Rapid restoration of arterial blood pressure was obtained in all ACEI-treated patients, mainly with the intravenous administration of 0.4 to 0.7 L of lactated Ringerʼs solution. Phenylephrine (0.38 ± 0.9 mg) was, however, required in four patients when mean arterial blood pressure was less than 60 mm Hg. These results suggest that hypotension associated with induction of anesthesia in hypertensive ACEI-treated patients is due to the inability of the heart to maintain cardiac output during acute decreases in ventricular volume. However, moderate intravascular administration of crystalloids and doses of phenylephrine were required to control blood pressure.