Comparison of the Potency of Phenylephrine and Norepinephrine Bolus Doses Used to Treat Postspinal Hypotension During Elective Cesarean Section

Abstract

(Int J Obst Anesth. 2019;38:25–31) Vasopressors to manage hypotension after spinal anesthesia are commonly used in obstetric patients. Phenylephrine has been considered the vasopressor of choice for many years, but it can result in reflex bradycardia and an associated fall in cardiac output. Norepinephrine is another potent vasopressor that has significant chronotropic effects that should limit bradycardia. However, there is little information about the preferred dose for managing postspinal hypotension in obstetric patients or its potency ratio compared with phenylephrine. This study aimed to calculate the 95% and 50% effective doses (ED95 and ED50) of both drugs and their potency ratio when administered as a bolus for the treatment of spinal-induced hypotension in women undergoing elective cesarean section.