Phenylephrine Infusion Versus Bolus Regimens During Cesarean Delivery Under Spinal Anesthesia: An Observational Study to Assess Hemodynamic Changes

Abstract

Background The objective of this study was to evaluate and compare the efficacy of two modes of phenylephrine administration, namely continuous infusion and intermittent bolus, in maintaining maternal hemodynamics during cesarean delivery under spinal anesthesia (SA). Methods Eighty patients undergoing cesarean delivery with SA were allocated into two groups. In group I, 40 patients were administered a prophylactic phenylephrine infusion at a rate of 75 mcg/min immediately after SA. Conversely, group B, consisting of 40 patients, received a 75 mcg bolus dose promptly after SA and subsequently whenever their blood pressure fell by more than 20% from the baseline value. Crucial variables, such as heart rate (HR), blood pressure, and side effects, were closely monitored at a three-minute interval in both groups. Following the delivery of the child, APGAR scores were documented at the first and fifth minutes, and the gathered data underwent analysis using SPSS Statistics, version 17.0 (SPSS Inc., Chicago, IL). Results The results revealed that baseline HR and blood pressure were similar in both groups. Nevertheless, the bolus group exhibited a higher mean HR, whereas the infusion group maintained a closer proximity to the baseline reading throughout the measurement period. Despite these variations, changes in HR did not demonstrate statistically significant differences between the two groups at any measuring intervals. Additionally, the mean systolic blood pressure in group B exhibited an initial decrease from the baseline, whereas group I displayed an increase compared to the baseline values. Importantly, neither group reported instances of nausea or vomiting, and the APGAR scores were comparable between them. Conclusion In conclusion, the study found that a phenylephrine bolus of 75 mcg was more effective in maintaining blood pressure within acceptable limits without causing bradycardia or hypertension when compared to a phenylephrine infusion.

Keywords: cesarean delivery; maternal hypotension; phenylephrine bolus; phenylephrine infusion; regional anesthesia.

Figure 1. Age profiles of patients in groups I and B

Figure 2. Comparative analysis of cardiovascular parameters between groups

HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure