Comparison of Bolus Ephedrine vs Mephentermine in the Management of Hypotension during Spinal Anaesthesia for Caesarean Section: A Randomised Clinical Trial

Introduction: Ephedrine and mephentermine are synthetic sympathomimetic drugs used as vasopressors. Ephedrine has direct and indirect effects on alpha, beta 1, and beta 2 receptors, and it also releases endogenous norepinephrine from synaptic storage sites. This leads to an elevation in Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP). On the other hand, mephentermine indirectly stimulates beta-adrenergic receptors and to some extent alpha-adrenergic receptors as well. Its primary effect is cardiac stimulation, which increases peripheral vascular resistance and contributes to an increase in blood pressure. Aim: The aim of this study is to examine the efficacy of ephedrine and mephentermine in the treatment of hypotension during Lower Segment Caesarean Section (LSCS). Materials and Methods: This double -blinded randomised clinical trial was conducted in the Department of Anaesthesiology among 90 pregnant females scheduled for caesarean delivery at Hind Institute of Medical Sciences, Sitapur, India from January 2021 to December 2022. Patients who developed hypotension (SBP <90 mmHg or <20% of the baseline) after receiving spinal anaesthesia were included in the study and divided into two groups. Group A received an intravenous bolus of 6 mg of ephedrine, and group B received an intravenous bolus of 6 mg of mephentermine. The variables studied included age, height, weight, Mean Arterial Pressure (MAP), Heart Rate (HR), SBP, DBP, bolus doses, and any side effects that occurred. HR, SBP, and DBP were recorded at baseline and then monitored every two minutes for a total of 10 minutes, and then every five minutes until the end of surgery. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) software version 21.0 for Windows, and the results were represented as numbers (%) and mean +/- Standard Deviation (SD). Results: The mean age of patients in group A and group B was 24.35 years and 24.72 years, respectively. All vital parameters were comparable. The need for bolus doses after hypotension was significantly higher in group B (1.68 +/- 0.81) than in group A (mean 1.28). The statistically significant complications identified were tachycardia, nausea, and vomiting, which were more prevalent in group B with 13 and 16 patients, respectively. Conclusion: In this study, the authors found that ephedrine was more effective than mephentermine in terms of the requirement for bolus doses and the occurrence of intraoperative side effects. The requirement for bolus doses and occurrence of significant complications were higher in the group that received mephentermine. Therefore, ephedrine bolus immediately following spinal anaesthesia would be a safe and effective technique for preventing hypotension in females scheduled for LSCS.