Dose-dependent hemodynamic effects of propofol induction following brotizolam premedication in hypertensive patients taking angiotensin-converting enzyme inhibitors

Abstract

Study Objective To determine a propofol dose that minimizes hemodynamic changes on induction of anesthesia in patients chronically taking angiotensin-converting enzyme inhibitors (ACEIs). Design Prospective, randomized trial. Setting Operating room of a university-affiliated general hospital. Patients 88 ASA physical status II and II hypertensive patients chronically taking ACEIs, scheduled for elective abdominal surgery with general anesthesia. Interventions Patients were premedicated with brotizolam and anesthesia was induced with propofol, fentanyl, and rocuronium; anesthesia was then maintained with isoflurane. Patients were randomly assigned to undergo anesthetic induction with propofol in doses of 1.3, 1.6, 2.0, or 2.3 mg/kg. Measurements Oscillometric blood pressure and heart rate were evaluated at one-minute intervals during the first 10 minutes of anesthesia. End-tidal isoflurane concentrations were also recorded. Episodes of hypertension, tachycardia, bradycardia, or hypotension (defined as > 30% of baseline values) were managed per protocol with esmolol, atropine, phenylephrine, or ephedrine. Administration of any of these drugs was considered a pharmacological intervention. Main Results After adjusting for covariables in a model assuming a linear relationship between dose and log-response, each propofol dose increase of 0.3 mg/kg was associated with a 31% increase in mean number of hypotensive/bradycardic episodes requiring interventions (95% confidence intervals of +5% and +65%; P = 0.018). Based on our model, a dose of 1.3 mg/kg resulted in the fewest number of pharmacological interventions. Conclusions In patients chronically taking ACEIs, low doses of propofol reduce hemodynamic instability.