Drug Design, Development and Therapy (May 2023)
Prophylactic Norepinephrine and Phenylephrine Boluses to Prevent Postspinal Anesthesia Hypotension During Cesarean Section: A Randomized Sequential Allocation Dose-Finding Study
Abstract
Lei Guo,1,* Xiangzhao Xu,2,* Rui Qin,1 Yongqiang Shi,1 Wei Xue,3 Ling He,3 Shuqin Ma,3 Yi Chen1 1Department of Anesthesiology and Perioperative Medicine, General Hospital of Ningxia Medical University, Yinchuan, People’s Republic of China; 2Department of Anesthesiology, The People’s Hospital of Nanchuan, Chongqing, People’s Republic of China; 3Department of Obstetrics, General Hospital of Ningxia Medical University, Yinchuan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yi Chen, Department of Anesthesiology and Perioperative Medicine, General Hospital of Ningxia Medical University, 804S Shengli Street, Yinchuan, Ningxia, 750004, People’s Republic of China, Tel +86-951-6743252, Email [email protected]: Norepinephrine and phenylephrine are widely used for obstetric anesthesia. Our central objective was to determine the ED (effective dose) 90 and potency ratio of prophylactic norepinephrine and phenylephrine boluses for preventing postspinal anesthesia hypotension during cesarean section.Methods: Patients scheduled for elective cesarean section (n = 80) were randomly allocated to receive prophylactic norepinephrine (NE) or phenylephrine (PE) boluses immediately after induction of spinal anesthesia. An initial dose of NE (3 μg) and PE (37.5 μg) was given to the first patient, and an up-and-down sequential allocation method was used to determine the next dose level according to the responses (the effectiveness for preventing postspinal anesthesia hypotension [defined as SBP < 80% of baseline value]). Primary outcomes were ED90 and the potency ratio of prophylactic norepinephrine and phenylephrine boluses. Secondary outcomes were the incidence of postspinal anesthesia hypotension, severe postspinal anesthesia hypotension, nausea, vomiting, bradycardia, hypertension, umbilical artery blood gas values, and Apgar scores.Results: The ED90 values for prophylactic norepinephrine and phenylephrine boluses were 8.0 μg (95% CI 7.1– 11.0 μg) and 90.9 μg (95% CI 82.0– 123.9 μg), respectively. The estimated relative potency ratio was 11.4:1. The incidence of bradycardia was lower in the NE group (2.5% vs 20%, P = 0.034). Other outcomes were comparable between the two groups.Conclusion: An 8-μg prophylactic bolus of norepinephrine and a 90-μg prophylactic bolus of phenylephrine can effectively prevent postspinal anesthesia hypotension in patients during cesarean section.Keywords: cesarean section, norepinephrine, phenylephrine, postspinal anesthesia hypotension
