Norepinephrine versus phenylephrine not tied to decrease in heart rate during C-section for twin pregnancy: Study

China: Infusion of norepinephrine versus phenylephrine failed to provide a less overall decrease in heart rate (HR) during the cesarean section for twins, concludes a recent study. However, there was a significant decrease in the incidence of bradycardia with norepinephrine use. The study was published in the journal BMC Anesthesiology on 08 January 2022. 

It is known that a twin gestation compared with a singleton pregnancy is featured by a greater increase in cardiac output. Norepinephrine therefore might be more suitable than phenylephrine for blood pressure maintenance during the cesarean section for twins. This is because phenylephrine causes reflex bradycardia and a resultant reduction in cardiac output. 

Considering the above, Han Huang, Translational Neuroscience Centre, West China Hospital, Sichuan University, Chengdu, China, and colleagues aimed to determine whether norepinephrine is superior to phenylephrine in maintaining maternal hemodynamics during the cesarean section for twins in a double-blinded, randomized clinical trial. 

For this purpose, the researchers obtained informed consent from all the patients before enrollment. The trial included 100 parturients with twin gestation undergoing cesarean section with spinal anesthesia. They were randomized to receive prophylactic norepinephrine (3.2 μg/min) or phenylephrine infusion (40 μg/min). The change of heart rate and blood pressure during the study period was the primary outcome.