Effect of norepinephrine and phenylephrine on maternal hemodynamic changes after spinal anesthesia in cesarean section: A randomized clinical trial.

Background: Hypotension after spinal anesthesia is a serious complication during cesarean sections, potentially reducing maternal cardiac output and placental blood flow, affecting both mother and baby. This study aimed to compare the effects of norepinephrine and phenylephrine on maternal hemodynamic changes following spinal anesthesia in elective cesarean surgeries. Methods: In this clinical trial study, 52 pregnant mothers' candidates for elective cesarean surgery were divided into two groups. After spinal anesthesia, the norepinephrine group received a 10-microgram bolus of norepinephrine, while the phenylephrine group received 100 micrograms of phenylephrine. The primary outcomes included blood pressure, heart rate, and measurement time. These were recorded three times before the start of spinal anesthesia, immediately after, and every 3 minutes until discharge, and then twice at 3-minute intervals after childbirth. Results: Mean arterial pressure in norepinephrine group was always higher than phenylephrine. Their difference was significant at the ninth minute (p<0.001) and the twelfth minute (P=0.009). Diastolic pressure in the two studied groups was significant at the ninth minute (p<0.001). 2 patients in norepinephrine group (7.6%) and 6 (23%)patients in phenylephrine group needed vasopressor. 3.8% of patients in norepinephrine group and 34% of patients in phenylephrine group had bradycardia (P=0.020). Conclusion: This study shows that norepinephrine is as effective as phenylephrine in preventing blood pressure drop in patients undergoing cesarean section, but it does not cause bradycardia.