Comparison of Bolus Phenylephrine, Ephedrine and Mephentermine for Maintenance of Arterial Pressure during Spinal Anaesthesia in Caesarean Section

Introduction: Hypotension following spinal anaesthesia for Caesarean section one of the common problem encountered by an anaesthesiologist. This study was aimed at comparing the efficacy of IV bolus Phenylephrine, Ephedrine and Mephentermine for maintenance of arterial blood pressure during spinal anesthesia in caesarean section. Materials and Methods: Ninty American Society of An esthesiologists (ASA) type 1 and 2 patients scheduled for elective as well as emergency caesarean section under spinal anaesthesia who developed hypotension were selected. These were allocated into 3 groups of 30 each to receive Group P-Phenylephrine 100 microgram, Group E-Ephedrine 6 mg, and Group M-Mephentermine 6 mg in 1 ml as bolus IV. Results: On intergroup comparison rise of diastolic blood pressure at 2, 4, and 6 minutes post study drugs were significantly less in Ephedrine group and Mephentermine group as compared to the Phenylephrine group (p<0.05). Similarly elevation of systolic arterial pressure in Phenylephrine group was significantly higher compared to other two groups for first 6 minutes. Thereafter the differences narrowed off. No significant differences were observed between changes in systolic and diastolic blood pressure of Ephedrine and Mephentermine group at any time. In Phenylephrine group, post study drug values of heart rate were decreased significantly from the values at onset of the hypotension till the end of the surgery when compared to other two groups (p<0.001). Conclusion : Phenylephrine group had quicker control of blood pressure compared to the other two groups. However, as the time elapsed all drugs achieved comparable control of blood pressure. Phenylephrine did show some advantage over others with regard to reduction in heart rate.