[Effective Dose of Prophylactic Norepinephrine for Preventing Hypotension under Combined Spinal and Epidural Anesthesia during Cesarean Section in Singleton Versus Twin Pregnancies].

Objective: To determine and compare the 90% effective dose (ED Methods: A randomized controlled trial was conducted, enrolling 200 pregnant women, 100 of which were of singleton pregnancies while the other 100 were of twin pregnancies, at West China Second University Hospital, Sichuan University between November 3, 2020 and June 2, 2021. All 200 subjects were to have Cesarean section under combined spinal-epidural anesthesia. By using a random number table, they were randomly assigned to five groups, receiving norepinephrine at the infusion dosage of 0.025, 0.050, 0.075, 0.100, and 0.125 μg/(kg·min), with 20 subjects of singleton pregnancy and 20 subjects of twin pregnancy in each group. Norepinephrine infusion started when the anesthesiologist initiated the spinal anesthetic injection and lasted until the delivery of the fetus. The primary outcome measure was the incidence of maternal hypotension during combined spinal-epidural anesthesia, up until the delivery of the fetus. Survival analysis, with survival being defined as not having hypotension, of the incidence of hypotension among the subjects was conducted. Probit regression was used to determine the ED Results: There was no significant difference in the baseline data or the anesthesia and operation data between pregnant women of singleton pregnancy and those of twin pregnancy ( Conclusion: There was no significant difference in the ED