Background and aim: Anesthesia induction by using propofol and morphine is associated with hypotension and bradycardia. In this randomized controlled trial, we compared the prophylactic effects of 0.1 and 0.2 mg/kg of ephedrine in reducing hemodynamic alterations related to anesthesia induction.

Methods: This is a clinical randomized controlled trial with 111 patients receiving elective surgery under general anesthesia. Patients were divided into three groups before inducing anesthesia with 2.5 mg/kg of propofol and 0.1 mg/kg of morphine: the control group (not received, n=37) , the low-dose group (0.1 mg/kg of ephedrine, n=37), and the high-dose group (0.2 mg/kg of ephedrine, n=37). Our primary objective was to compare the efficacy of 0.1 and 0.2 mg/kg of ephedrine in preventing hypotension due to anesthesia induction.

Results : The incidence of hypotension was highest in the control group (29.7%, 70.3%, 81.1%, 78.4% and 81.1% at 1, 2, 3, 4 and 5 min after anesthesia induction, respectively). and lowest in the high-dose group (0%, 0%, 2.7%, 10.8% and 13.5% at 1, 2, 3, 4 and 5 min, respectively). In the overall 5 minutes comparison after anesthesia induction, significant differences in the mean differences of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were observed between the high-dose and control groups (P<0.001, all parameters) and between the high- and low-dose groups (P<0.001 in SBP and MAP, P=0.001 in DBP). Between the low-dose and control groups, we observed only significant differences in the mean differences of SBP (P<0.001) and MAP (P=0.018). The comparison of hemodynamic data at 5 minutes after anesthesia induction also demonstrated significant differences in the mean differences of SBP, DBP and MAP between the high-dose and control groups (P<0.001, all parameters) and between the high- and low-dose groups (P=0.001 in SBP and DBP, P<0.001 in MAP). There was only a significant difference in the mean difference of SBP (P=0.010) between the low-dose and control groups. No significant difference in heart rate was observed between these three groups.

Conclusion: The hypotensive effect of anesthesia induction with propofol and morphine was eliminated by administering 0.2 mg/kg of ephedrine only. Both 0.1 and 0.2 mg/kg of ephedrine did not cause significant tachycardia at 1-5 min after anesthesia induction.