Comparison of Phenylephrine, Ephedrine and Mephentermine for Control of Hypotension following Spinal Anaesthesia for Infra-Umbilical Surgeries

Background: Neuraxial anaesthesia remains the preferred choice for infra-umbilical surgeries Three vasopressors phenylephrine, ephedrine and mephentermine in intravenous bolus form, are effective in maintenance of blood pressure (BP). Absolute supremacy of one vasopressor over the others is not yet established. The current study was undertaken to compare the three vasopressor for maintenance of BP during spinal anesthesia. Material and Methods: Clinical observational study over a period of one year was conducted in a tertiary medical center and teaching hospital in Maharashtra. Ninety patients of American Society of Anaesthesiologist classification: class I and II were distributed into three groups of thirty patients each. Following hypotension, group A received ephedrine 10 mg, group B received mephentermine 10 mg and group C received phenylephrine 100?g as intravenous bolus in 1 ml of 0.9% sodium chloride solution. Blood pressure, heart rate and oxygen saturation were recorded every 2 minutes for first 10 minutes and then every 15 minutes for one hour. Results: In ephedrine group 9 (30%) patients required second dose and 8 (26%) patients developed tachycardia. In mephentermine group, 33% patients developed tachycardia and 4 (13%) developed hypertension. In phenylephrine group 8 (26%) developed bradycardia and 3 (10%) developed severe bradycardia pulse rate dropped to 42 /min corrected by giving injection atropine and in all patients BP was maintained within 6-8 minutes after giving vasopressors and only in ephedrine group i.e. 9 patients required two doses of ephedridine. Conclusions: All the three vasopressors were equally effective in maintaining blood pressure after spinal anaesthesia induced hypotension. Elevation of systolic pressure in phenylephrine group was significantly high for first 6 min of bolus dose as compared to other two and bradycardia in these patients was a significant finding.