ED95 determination of continuous norepinephrine infusion for preventing spinal anesthesia-induced hypotension in obese parturients during cesarean delivery
TL;DR
The findings indicate that obese parturients require a significantly higher prophylactic dose of norepinephrine infusion to prevent spinal anesthesia-induced hypotension compared to the non-obese counterparts and underscore the importance of individualized dosing strategies based on BMI to optimize hemodynamic management in obese parturients undergoing cesarean delivery.
Abstract
Background Norepinephrine is an effective vasopressor for preventing and managing spinal anesthesia-induced hypotension during cesarean delivery. Nevertheless, data regarding the 95% effective dose (ED95) of continuous norepinephrine infusion in obese parturients remain scarce. Methods This prospective dose-finding study enrolled parturients scheduled for elective cesarean delivery under spinal anesthesia. Participants were stratified into two groups based on body mass index (BMI): non-obese group (BMI <30 kg/m2) and obese group (BMI ≥30 kg/m2). Intravenous norepinephrine infusion was initiated at a dose of 0.01 μg/kg/min in the first participant, with subsequent dosages adjusted according to the preceding patient’s response using a biased coin design up-and-down sequential method. Spinal anesthesia-induced hypotension was defined as a mean arterial pressure of below 65 mmHg sustained for more than 1 minute within 30 min following intrathecal injection. The 95% effective dose (ED95) was estimated via isotonic regression coupled with bias-corrected bootstrapping. Maternal and neonatal outcomes, including adverse events, were recorded. Results Eighty parturients were included in the analysis. The ED95 of norepinephrine was determined to be 0.045 μg/kg/min (95% confidence interval [CI], 0.03–0.05 μg/kg/min) in the non-obese group and 0.0662 μg/kg/min (95% CI, 0.055–0.075 μg/kg/min) in the obese group. No significant differences were observed in maternal or neonatal outcomes between the two cohorts. Conclusion The findings indicate that obese parturients require a significantly higher prophylactic dose of norepinephrine infusion to prevent spinal anesthesia-induced hypotension compared to the non-obese counterparts. These results underscore the importance of individualized dosing strategies based on BMI to optimize hemodynamic management in obese parturients undergoing cesarean delivery.