Comparative Evaluation of Phenylephrine and Ephedrine Effects on Maternal and Fetal Safety in Cesarean Delivery Under Spinal Anesthesia

Abstract

Background: Administering of phenylephrine together with ephedrine as the initial vasopressor strategy during spinal anesthesia for cesarean delivery was associated with a lower frequency of neonatal acidemia, defined as an umbilical arterial pH below 7.20, compared with the use of ephedrine alone. Methods: This investigation was conducted to compare the effectiveness of three vasopressor infusion regimens in maintaining maternal systolic blood pressure during elective cesarean section under spinal anesthesia. Participants were allocated to receive either phenylephrine at a concentration of 100 μg/mL, ephedrine at 3 mg/mL, or a combined solution containing phenylephrine 50 μg/mL and ephedrine 1.5 mg/mL. Each infusion was titrated to maintain systolic arterial pressure close to the pre-spinal baseline value. Results: Two of ninety-six patient born acidotic neonate in the phenylephrine group (P = 0.004) and the combination group 2 of 94 (P = 0.005) which less than in the ephedrine group 20 of 96. Maternal systolic blood pressure was successfully maintained in all treatment groups, with median values corresponding to 98% of baseline in the phenylephrine group, 100% in the ephedrine group, and 101% in the combination group, without statistically significant differences (P = 0.11). Maternal heart rate was significantly greater among women receiving ephedrine, reaching a median of 107% of baseline, compared with 88% in the phenylephrine group and 96% in the combination group (both P < 0.0001). Gastrointestinal side effects also differed markedly between groups. Phenylephrine was associated with the lowest incidence of nausea (17%) and no cases of vomiting, whereas ephedrine produced the highest rates of nausea (66%) and vomiting (36%). The combination regimen resulted in intermediate frequencies of nausea (55%) and vomiting (18%), both significantly higher than those observed with phenylephrine alone (P < 0.0001). Conclusions: Continuous infusion of phenylephrine during elective cesarean delivery under spinal anesthesia associated non-significant differences   regarding maternal and neonatal outcome when compared with ephedrine infusion. Specifically, phenylephrine significantly reduced the incidence of fetal acidemia as well as maternal nausea and vomiting while maintaining maternal blood pressure effectively. Although combining phenylephrine with ephedrine also decreased the occurrence of fetal acidemia relative to ephedrine alone, it failed to produce any additional improvement in neonatal acid–base status over phenylephrine monotherapy and was associated with a higher frequency of maternal nausea and vomiting. These findings support the use of phenylephrine alone as the preferred first-line vasopressor during cesarean delivery under spinal anesthesia.