Comparison of Phenylephrine Infusion Versus Boluses for Management of Blood Pressure in Elective Caesarean Section

Abstract

Objective: To compare the efficacy of intravenous phenylephrine infusion versus boluses for blood pressure management in elective caesarean sections.

Study Design: Quasi-experimental study.

Place and Duration of Study: Anaesthesia Department, Combined Military Hospital, Rawalpindi Pakistan, from Feb to Jul 2022.

Methodology: Three hundred ninety patients requiring elective caesarean section were divided into an Infusion Group (n=195) and a Bolus Group (n=195). The Infusion Group received phenylephrine with 100 mcg/ml titration immediately after spinal anaesthesia as per weight and height at a 1 ml/minute rate and continued for 5 minutes. Infusion stopped if MAP at 5 minutes was above baseline and restarted if dropped below baseline in subsequent readings. In the case of bradycardia, 600mcg of Glycopyrrolate was administered. Parameters recorded at 1, 5, 10 and 15-minute intervals. In the bolus group, total numbers of 100mcg boluses at the end of fifteen minutes were recorded. Protocol for bradycardia and data record intervals was the same. The primary variables were mean arterial pressure (MAP), heart rate(HR), the total dose of phenylephrine used, and nausea and vomiting.
Results: Primary outcome variables showed consistent improvement in maintaining MAP in the Infusion Group versus the Bolus Group (p<0.05). A similar trend was seen with heart rate between both groups (p<0.05). However, the infusion group had an average fall in heart rate compared to the bolus group at all-time intervals.
Conclusion: Phenylephrine infusion offers better hemodynamic stability, requiring less ephedrine support than when given in boluses.