Comparison of efficacy and safety of preemptive infusion protocols of ephedrine and phenylephrine – prevention of hypotension and effects on hemodynamic parameters during spinal anesthesia for caesarean section

Abstract

Introduction/Objective Spinal anesthesia (SA) for cesarean section may lead to significant changes in hemodynamic parameters, especially hypotension. The aim of this study was to determine and compare the efficacy and safety of preemptive infusion protocols of the two most commonly used vasopressors, ephedrine (Group E, n = 29) and phenylephrine (Group P, n = 31) not only on prevention of hypotension but also to determine their effect on hemodynamic parameters, such as stroke volume (SV) and cardiac output (CO) using a continuous non-invasive hemodynamic monitor.

Methods The infusion of ephedrine was administered at the rate of 5 mg/min. immediately after SA. Phenylephrine was administered at an infusion rate of 25 μg/min for two minutes prior to SA.

Results In Group E, mean systolic blood pressure (SBP) and heart rate (HR) were similar to baseline. CO was higher (p < 0.001), while systemic vascular resistance (SVR) was lower than baseline (p < 0.001). In Group P, mean SBP and diastolic blood pressure (DBP) were lower than baseline, respectively (p = 0.006, p < 0.001). SBP, DBP, CO, SV, SVR, and HR were significantly different between the E and P groups (p < 0.001).

Conclusion E and P vasopressors are both effective in the prevention of hypotension during SA.

Keywords: cesarean section; spinal anesthesia; ephedrine; phenylephrine; hypotension; hemodynamic parameters