Norepinephrine vs. phenylephrine for spinal hypotension in cesarean section: a network meta-analysis

Postspinal hypotension (PSH) during cesarean section (CS) often causes maternal intraoperative nausea and vomiting (IONV) and fetal acidosis. Phenylephrine (PE) and norepinephrine (NE) are commonly used for management; however, the optimal agent and method (bolus vs. infusion) remains uncertain. This review assessed bolus and infusion of PE and NE for IONV and PSH during CS.

Systematic searches of MEDLINE, Embase, CENTRAL, and unpublished studies identified randomized controlled trials (RCTs) on PE and NE administration during CS under spinal anesthesia. Primary outcomes included IONV and PSH, whereas secondary outcomes encompassed Apgar scores, umbilical artery pH, rescue vasopressor bolus requirements, and adverse events. A random-effects meta-analysis and the Confidence in Network Meta-Analysis tool were utilized.

Among 74 RCTs (7798 patients), NE and PE infusion reduced IONV compared with PE bolus (risk ratio [RR]: 0.47; 95% confidence interval [CI] 0.34-0.66; RR: 0.54; 95% CI 0.42-0.69, high confidence). Similarly, these approaches reduced PSH (NE infusion: RR: 0.25; 95% CI 0.21-0.31, high confidence; PE infusion: RR: 0.29; 95% CI 0.24-0.34, moderate confidence). Rescue vasopressor bolus requirements showed a similar trend. Apgar scores and umbilical artery pH were comparable across all groups. Adverse event varied, with bradycardia more common with PE, tachycardia with boluses, and dizziness with PE bolus. Hypertension was more frequent with infusions. In prophylactic studies, hypotension trends persisted, but no differences were observed in IONV.

Prophylactic continuous infusion appears to be a favorable strategy for managing PSH and IONV during CS. No significant difference was observed between PE and NE infusions in preventing PSH and IONV.