Prophylactic phenylephrine for caesarean section under spinal anaesthesia: systematic review and meta-analysis

Area of Science:

• Obstetrics and Gynecology
• Anesthesiology
• Pharmacology

Background:

• Spinal anesthesia for cesarean delivery can cause hypotension.
• Prophylactic vasopressors are used to manage this complication.
• Phenylephrine is a commonly considered vasopressor, but its benefits and harms require clear definition.

Purpose of the Study:

• To systematically review the evidence on the prophylactic use of phenylephrine during cesarean section under spinal anesthesia.
• To evaluate the efficacy and safety of phenylephrine in preventing maternal hypotension and other adverse events.
• To compare phenylephrine with placebo and ephedrine infusions.

Main Methods:

• Systematic review of 21 randomized controlled trials.
• Inclusion of 1504 women undergoing cesarean section under spinal anesthesia.
• Analysis of maternal and neonatal outcomes, including hypotension, nausea, vomiting, hypertension, bradycardia, and neonatal endpoints.

Main Results:

• Phenylephrine infusion significantly reduced the risk of hypotension compared to placebo (RR 0.36; 95% CI 0.18–0.73) and ephedrine infusion (RR 0.58; 95% CI 0.39–0.88).
• Phenylephrine also decreased the risk of hypotension (RR 0.37; 95% CI 0.19–0.71) and nausea/vomiting (RR 0.39; 95% CI 0.17–0.91) post-delivery compared to placebo.
• No significant effects were observed on maternal hypertension, bradycardia, or neonatal outcomes.

Conclusions:

• Prophylactic phenylephrine is effective in reducing hypotension and nausea/vomiting following spinal anesthesia for cesarean delivery, particularly with bupivacaine doses exceeding 8 mg.
• Phenylephrine does not appear to increase risks of hypertension, bradycardia, or adverse neonatal outcomes.
• The findings support the use of phenylephrine for managing hypotension in this patient population.