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

Area of Science:

• Anesthesiology
• Obstetrics
• Pharmacology

Background:

• Postspinal hypotension (PSH) is a frequent complication during cesarean section (CS), often leading to intraoperative nausea and vomiting (IONV) and potential fetal acidosis.
• Phenylephrine (PE) and norepinephrine (NE) are commonly used vasopressors, but optimal administration methods (bolus vs. infusion) for PSH and IONV prevention remain debated.

Purpose of the Study:

• To systematically review and compare the efficacy of phenylephrine (PE) and norepinephrine (NE) administered as bolus or infusion for managing PSH and IONV during CS.
• To evaluate secondary outcomes including Apgar scores, umbilical artery pH, and adverse events associated with different vasopressor strategies.

Main Methods:

• A systematic literature search was conducted across major databases (MEDLINE, Embase, CENTRAL) to identify relevant randomized controlled trials (RCTs).
• A random-effects meta-analysis was performed to synthesize data from 74 RCTs involving 7798 patients.
• The Confidence in Network Meta-Analysis tool was used to assess the certainty of evidence.

Main Results:

• Both NE and PE infusions significantly reduced IONV compared to PE bolus (high confidence).
• Continuous infusions of NE and PE were effective in reducing PSH (high and moderate confidence, respectively).
• No significant differences were found in Apgar scores or umbilical artery pH; however, adverse events like bradycardia (PE) and tachycardia (boluses) were noted.

Conclusions:

• Prophylactic continuous infusion of vasopressors is a favorable strategy for managing PSH and IONV during CS.
• No significant difference exists between PE and NE infusions in preventing PSH and IONV, suggesting both are viable options.