Enalapril premedication attenuates the blood pressure response to tracheal intubation and stabilizes postoperative blood pressure after controlled hypotension with sodium nitroprusside in neurovascular patients

Oral premedication with enalapril, 0.1 mg/kg was compared with placebo in 22 patients subjected to craniotomy and ligation of an intracranial aneurysm or extirpation of an arteriovenous malformation. Balanced hypotensive anesthesia was used with sodium nitroprusside (SNP) as the main hypotensive agent. The hypertensive response to laryngoscopy and tracheal intubation was significantly attenuated by enalapril (p = 0.020). The mean blood pressure was lower and more stable in the intensive care unit after enalapril than after placebo (p = 0.044). The median SNP dose rate tended to be lower in the enalapril-pretreated patients [0.6 (range of 0-3.5) micrograms/kg/min] compared to the placebo group [1.4 (0.4-5.8) micrograms/kg/min] (p = 0.12). Concentrations of plasma catecholamines, vasopressin, and endothelin as well as serum osmolality, arterial blood gases, and plasma electrolytes and level of consciousness were repeatedly measured. Enalapril had no significant effects on these variables. Plasma renin activity was increased and serum angiotensin converting enzyme (ACE) activity was reduced in the expected manner by enalapril. We found premedication with an ACE inhibitor favorable for hypotensive anesthesia in neurovascular patients as assessed by the circulatory responses.