A Clinical Trial on the Effects of Different Regimens of Phenylephrine on Maternal Hemodynamic After Spinal Anesthesia for Cesarean Section

BACKGROUND: Phenylephrine is used to prevent and treat hypotension during spinal anesthesia for cesarean delivery. OBJECTIVES: The present study aims to investigate the effects of different regimens of phenylephrine on blood pressure of candidates for the cesarean section. METHODS: In this double-blind, randomized clinical trial, a total of 120 candidates of elective cesarean delivery under spinal anesthesia was randomly categorized into three groups. Groups 1, 2, and 3 received bolus and prophylactic saline (control group), prophylactic bolus phenylephrine (100 µg), and prophylactic phenylephrine infusion (50 µg/min), respectively. The incidence of hypotension, maternal hemodynamics, hypertension, rescue phenylephrine dose, nausea, and vomit were compared between the groups. RESULTS: In all the three groups, the incidence of nausea and vomit, bradycardia, hypertension, and neonatal Apgar score were not statistically different (P > 0.05). However, the adjuvant phenylephrine dose requirement was remarkably different. Moreover, the mean systolic blood pressure differed significantly in the second and 7th minutes after the spinal block (P < 0.05). 35% in the first group, 15% in the second group, and 2.5% in the third group had hypotension (P = 0.001). Apart from the first measurement after spinal anesthesia, the mean heart rate showed no significant difference between the groups. CONCLUSIONS: The use of prophylactic phenylephrine infusion is recommended to control the optimal blood pressure in parturients undergoing cesarean section after spinal anesthesia.