Norepinephrine versus phenylephrine for post-spinal hypotension during caesarean section

Background: Currently, phenylephrine is the first-choice vasopressor for prevention and treatment of post- spinal hypotension in caesarean section. Phenylephrine is a potent α-adrenergic vasopressor with a dose- dependent reflex bradycardia and could in theory cause a drop in cardiac output and lower uteroplacental blood flow. Hence, there is an increased interest in the use of norepinephrine because of its weak β-adrenergic activity which can counteract the reflex bradycardia. Methods: Using PRISMA guidelines, we conducted a literature search and identified 35 trials related to the comparison of norepinephrine with phenylephrine for the prevention and/or treatment of post-spinal hypotension during caesarean section. Results: In the present review thirty-five trials were reviewed which compared norepinephrine with phenylephrine for the prevention and/or treatment of post-spinal hypotension during caesarean section. The characteristics of all these trials were summarized in Table I. The effect on maternal hemodynamics, maternal adverse events, and neonatal outcome were summarized in Tables II, III, IV and V. Conclusion: We concluded that in the healthy parturient delivering an expected healthy fetus via elective caesarean section there is increasing evidence to support norepinephrine as an effective and safe vasopressor in comparison to phenylephrine. Questions about the fetal safety of norepinephrine have been raised and therefore in high-risk populations (compromised fetuses, unhealthy parturients) and during emergency caesarean section, there is a need for more research before we can recommend the routine use of norepinephrine.