Fluid responsiveness-guided individualized strategy for preventing hypotension after spinal anesthesia in cesarean delivery: a randomized trial of prehydration versus norepinephrine preinfusion

This study aimed to evaluate the efficacy of fluid responsiveness-guided strategies for preventing spinal anesthesia-induced hypotension (SAIH) in parturients undergoing cesarean delivery, comparing prophylactic fluid loading with norepinephrine infusion. In this fluid responsiveness-based stratified randomized controlled trial, eligible parturients were stratified into fluid responsive (FR(+)) and non-fluid responsive (FR(-)) cohorts according to carotid corrected flow time (FTc). Each stratum had a preset sample size of 236, and within each stratum, participants were randomly assigned to receive either prophylactic colloid infusion (Co) or norepinephrine infusion (NE), ultimately forming four subgroups: FR(+)/Co, FR(+)/NE, FR(-)/Co, and FR(-)/NE.Primary outcomes included the incidence of SAIH and maximum reduction in mean arterial pressure (MAP). Secondary outcomes encompassed neonatal umbilical cord blood gas analysis, Apgar scores, intraoperative hemodynamic changes, and postoperative recovery parameters. Among fluid-responsive parturients, prophylactic fluid loading (FR(+)/Co) and norepinephrine infusion (FR(+)/NE) demonstrated comparable efficacy in preventing SAIH (16.7% vs. 15.1%, P > 0.05). In contrast, non-fluid-responsive parturients receiving fluid loading (FR(-)/Co) had a significantly higher SAIH incidence (34.2%) compared to those receiving norepinephrine (FR(-)/NE, 13.6%, P = 0.0004). Neonatal umbilical cord blood lactate levels were higher in the FR(+)/NE group compared to the FR(+)/Co group (1.66 ± 0.25 mmol/L vs. 1.55 ± 0.28 mmol/L, P = 0.006), suggesting potential fetal hypoxia. Additionally, the FR(+)/NE group exhibited prolonged postoperative gastrointestinal recovery times compared to the FR(+)/Co group (29 [20, 39] h vs. 24 [16, 35] h, P = 0.0438). Fluid loading is optimal for fluid-responsive parturients, whereas norepinephrine infusion is superior for non-fluid-responsive parturients. These findings advocate for fluid responsiveness-guided individualized SAIH prevention strategies to optimize maternal and neonatal outcomes. This trial was prospectively registered at ClinicalTrials.gov (ChiCTR2400084392) on May 15, 2024, prior to participant enrollment.