Prevention of hypotension associated with the induction dose of propofol: A randomized controlled trial comparing equipotent doses of phenylephrine and ephedrine.

BACKGROUND AND AIMS: Propofol, the most commonly used intravenous (IV) anesthetic agent is associated with hypotension on induction of anesthesia. Different methods have been used to prevent hypotension but with variable results. The objective of this study was to evaluate efficacy of equipotent doses of phenylpehrine and ephedrine in preventing the hypotensive response to the induction dose of propofol.

MATERIAL AND METHODS: One hundred thirty five adult patients were randomised to one of the study groups: propofol-saline (PS), propofol-phenylephrine (PP) or propofol-ephedrine (PE) by adding study drugs to propofol. Anesthesia was induced with a mixture of propofol and the study drug. Patients were manually mask-ventilated for 5 min using 40% oxygen in nitrous oxide and isoflurane at 1%. A baseline mean arterial pressure (MAP) was recorded prior to induction of anesthesia. Systolic, diastolic and mean blood pressure and heart rate were recorded every minute for up to 5 min after induction. Hypotension was defined as a 20% decrease from the baseline MAP.

RESULTS: There were no significant demographic differences between the groups. Overall incidence of hypotension in this study was 38.5% (52/135). Rate of hypotension was significantly higher in group PS than group PP (60% vs. 24.4% P = 0.001) and group PE (60% vs. 31.1% P = 0.005). In contrast, a significant difference in rate of hypotension was not observed between groups PP and group PE.

CONCLUSION: In equipotent doses, phenylephrine is as good as ephedrine in preventing the hypotensive response to an induction dose of propofol.