Comparison of Frequency of Hypotension with Prophylactic Phenylephrine versus Placebo in Patients Undergoing Induction of General Anaesthesia with Propofol

Objective: To assess the efficacy of prophylactic intravenous phenylephrine in preventing hypotension following propofol injection during the induction of general anaesthesia. Methodology:Thiswas aquasi-experimental studyconductedattheDepartmentofCardiacAnaesthesia, Rehmatul-lil-Alameen Institute of Cardiology (RAIC), Lahore, from 13 Jan 2025 to 13 July 2025.A total of 60 patients scheduled for elective surgeries under general anaesthesia were assigned to two groups (n=30 each).GroupPreceived100 mcg ofphenylephrine intravenously beforepropofol administration, whileGroupCreceivedanequivalentvolumeofnormal saline.Theprimaryoutcomewas the incidence of hypotension, defined as a >20% decrease in systolic blood pressure from baseline within 5 minutes post-induction. Subgroup analyses were conducted based on age, gender, BMI, and baseline blood pressure. Results: The mean age of the patients was 31.82±9.64 years. There were 31 (51.7%) male and 29 (48.3%) 2 female patients. The mean BMI of these patients was 28.26±3.69 Kg/m , while the mean baseline systolic blood pressure was 145.42±16.47 mmHg. Thirteen (21.7%) patients developed hypotension after propofol injection. Hypotension occurred in 0% of patients in the phenylephrine group compared to 43.3% in the placebo group (p < 0.001). Subgroup analyses also showed statistically significant reductions in hypotension across all age and gender categories, and in higher BMI and baseline systolic BPranges for the phenylephrine group. Conclusion: Prophylactic administration of phenylephrine is highly effective in preventing propofolinduced hypotension during induction of general anesthesia without associated adverse effects. Keywords: Anesthesia, BMI, General Anesthesia, Hemodynamics, Hypotension, Phenylephrine, Propofol, Vasopressor