Phenylephrine vs ephedrine in cesarean delivery under spinal anesthesia: A systematic literature review and meta-analysis

BACKGROUND: In the past 20 years, many studies compared phenylephrine with ephedrine to prevent or treat hypotension in elective or emergency cesarean delivery and parturients with pre-eclampsia. A meta-analysis of the abovementioned trials is needed. METHODS: Several databases (PubMed, Embase, Web of Science and Cochrane Library) were searched from inception to April 2018 for trials comparing phenylephrine with ephedrine in cesarean delivery. The primary outcome is the incidence of maternal hypotension. RESULTS: Thirty-six trials (2439 patients) with elective cesarean delivery, three trials (400 patients) with emergency cesarean delivery and three trials (192 patients) with parturients with pre-eclampsia were included and analyzed. The incidence of hypotension did not differ in the elective surgery group (relative risk 0.83, 95% CI 0.66 to 1.05), emergency surgery group (relative risk 1.02, 95% CI 0.87 to 1.19) and pre-eclamptic parturients group (relative risk 0.93, 95% CI 0.63 to 1.37). The phenylephrine group had a higher incidence of bradycardia and lower incidences of tachycardia and nausea or vomiting in all three patient groups. The phenylephrine group also had lower fetal acidosis rate, higher umbilical artery and vein pH values and less base excess in the elective surgery. The abovementioned outcomes were similar in the emergency surgery group and the pre-eclampsia group. Publication bias for hypotension was detected. However, the trim and fill method demonstrated that the publication bias had little impact on hypotension. Trial sequential analysis of hypotension in elective surgery showed that this meta-analysis lacked a sufficient cumulative sample size and that further studies should be included. CONCLUSION: Phenylephrine and ephedrine were both effective in maintaining hemodynamic balance. Newborns benefited more from phenylephrine in elective cesarean delivery, but not in emergency cesarean delivery or in parturients with pre-eclampsia. More trials should be included to achieve more conclusive results.