Norepinephrine versus phenylephrine infusion for prophylaxis against post-spinal anaesthesia hypotension during...

Prophylactic vasopressors are fundamental during caesarean delivery under spinal anaesthesia. The aim of this work is to compare the efficacy and safety of phenylephrine and norepinephrine when used in variable infusion rate during caesarean delivery.

A randomised, double-blinded, controlled trial was conducted including mothers scheduled for elective caesarean delivery under spinal anaesthesia. Participants were allocated to two groups norepinephrine group (n = 60), and phenylephrine group (n = 63). Participants received prophylactic vasopressors after spinal block at rate started at 0.05 mcg/kg/min and 0.75 mcg/kg/min respectively. The rate of vasopressor infusion was manually adjusted according to maternal systolic blood pressure. Both groups were compared according to incidence of post-spinal hypotension (the primary outcome), incidence of bradycardia, incidence of reactive hypertension, systolic blood pressure, heart rate, rescue vasopressor consumption, number of physician interventions, and neonatal outcomes.

One hundred and twenty-three mothers were available for final analysis. Both groups were comparable in the incidence of post-spinal hypotension (32% versus 30%, P = 0.8). The number of physician intervention was lower in norepinephrine group. The incidence of bradycardia and the incidence of reactive hypertension were potentially lower in norepinephrine group without reaching statistical significance, (13% vs. 21%, P = 0.3) and (12% vs. 24%, P = 0.1). Rescue vasopressor consumption, and neonatal outcomes were comparable between both groups.

When given in a manually adjusted infusion, norepinephrine effectively maintained maternal SBP during caesarean delivery under spinal anaesthesia with lower number of physician interventions, and likely less incidence of reactive hypertension and bradycardia compared to phenylephrine.