Vasopressors For Managing Maternal Hypotension During Cesarean Section Under Spinal Anesthesia: A Systematic Review And Network Meta-Analysis

Introduction: Spinal anesthesia during elective cesarean section often induces maternal hypotension, and vasopressors are the most reliable agents to counteract this. We conducted a systematic review and network meta-analysis to compare and specifically evaluate the efficacy of vasopressors in preventing maternal hypotension (effectiveness) and decreasing fetal acidosis (safety) in parturients undergoing spinal anesthesia for cesarean section. Methods: We performed a systematic and comprehensive search to identify all randomized controlled studies on vasopressors to manage maternal hypotension during cesarean section under spinal anesthesia, which had been published until June 30, 2019 and updated until September 20, 2020. A network meta-analysis was conducted to combine direct and indirect comparisons of vasopressors. The primary outcomes included minimum systolic blood pressure, the incidence of hypotension, and fetal acidosis. Stata SE 15.0 was used for the meta-analysis. Results: Forty-five studies (n = 3,369) with six different vasopressors injected using various methods were included. Based on the surface under the cumulative ranking curve (SUCRA) value, intravenous (IV) continuous infusion of mephentermine (SUCRA value 83.4%) was the most efficacious vasopressor with the lowest incidence of hypotension, followed by continuous infusion of ephedrine with norepinephrine bolus (81.6%) and norepinephrine (76.4%). Compared with an IV bolus injection, all analyzed vasopressors were more effective when they were infused continuously for managing maternal hypotension. In terms of safety, only angiotensin II as an IV continuous infusion (94.7%) was efficacious in preventing fetal acidosis, resulting in a pH closer to 7.4, and there were no significant differences in umbilical arterial pH between the test and control groups. Conclusion: Clinicians should continuously infuse vasopressors to manage maternal hypotension during cesarean section under spinal anesthesia. According to SUCRA, norepinephrine administered as an IV continuous infusion was the third most efficacious vasopressor with the lowest incidence of maternal hypotension, and it could be a potential alternative to phenylephrine. Meanwhile, only angiotensin II administered as an IV continuous infusion caused less umbilical arterial acidosis than the control group.