Comparison of Continuous Infusion of Epinephrine and Phenylephrine on Hemodynamics During Spinal Anesthesia for Cesarean Delivery: A Randomized Controlled Trial

Purpose: Phenylephrine is a commonly used vasopressor for the treatment of spinal-induced hypotension in obstetric patients, but it is associated with reflex bradycardia and a corresponding decrease in cardiac output. This study aims to assess the effectiveness of continuous epinephrine versus phenylephrine infusion in the prevention of postspinal maternal hypotension.

Methods: Eighty-two women undergoing cesarean delivery were randomly divided into the epinephrine group (group E) and the phenylephrine group (group P). The patients received a continuous infusion of phenylephrine 1 μg kg^-1 min^-1 or epinephrine 0.1 μg kg^-1 min^-1 synchronously with intrathecal administration. Hemodynamic parameters were recorded, and umbilical cord blood gases were analyzed after delivery. The incidence of maternal hypotension, bradycardia, nausea, and vomiting was recorded.

Findings: Blood pressure, heart rate, and cardiac output after spinal anesthesia induction were greater in group E than in group P (P < 0.05). In addition, there was a significant difference in the incidence of bradycardia (5% vs 22.5%, P = 0.02) and mean (SD) umbilical artery pH (7.31 [0.07] vs 7.28 [0.06], P = 0.04) between the groups.

Implications: With the dose of 0.1 μg kg^-1 min^-1, infusion of epinephrine is more effective at maintaining blood pressure close to baseline during spinal anesthesia with a lower decrease in maternal heart rate and cardiac output compared with phenylephrine. Epinephrine may be superior to phenylephrine in terms of the incidence of bradycardia and umbilical artery pH. chictr.org.cn identifier: ChiCTR-IIC-17010960.

Keywords: cesarean delivery; epinephrine; phenylephrine; spinal anesthesia; umbilical artery pH.