To Compare the Efficacy of Phenylephrine and Mephentermine in Maintaining Arterial Pressure During Spinal Anaesthesia in Infra Umbilical Surgeries

Introduction: It is important to find an effective method to prevent and treat hypotension during subarachnoid block. Hence we compare the bolus doses of Phenylephrine and Mephentermine to treat hypotension post subarachnoid block. Methods: This randomized study was conducted in 100 patients of ASA I or II physical status undergoing infraumbilical surgeries under subarachnoid block. Patients were randomized into 2 groups of 50 each. Group P-Phenylephrine of 0.1 mg I.V bolus and Group M-Mephenteramine 6mg I.V bolus given when patient develops hypotension >20% basal respectively. Both the groups received 3ml of 0.5% hyperbaric bupivacaine for subarachnoid block. Vital parameters like blood pressure, heart rate and oxygen saturation were recorded. Any side effects observed were also recorded. Results: The demographic profile were comparable and statistically similar in both the groups. Both the vasopressors were able to maintain blood pressure above the hypotensive values in their respective groups successfully. The number of hypotension episodes was higher in Group P(34%) than Group M(32%) but statistically insignificant. The average number of drug doses required for recovery from hypotension was higher in the Group P(1.41) than Group M(1.25). The number of episodes of bradycardia was higher in the phenylephrine group(16%) than in the mephentermine group(4%). Conclusion: We conclude that intravenous bolus of phenylephrine and mephentermine are both effectve at maintaining intraoperative blood pressure during spinal anaesthesia in infraumbilical surgeries but mephenteramine is better than phenylephrine in maintaining BP persistently high and has lesser incidence of bradycardia.