What question did this study set out to answer?

This study aims to find the effective doses (ED90) of phenylephrine and norepinephrine for maintaining maternal blood pressure during cesarean delivery.

May 3, 2026Frontiers in Pharmacology0 citationsOpen Access

Determining the ED90 of prophylactic phenylephrine and norepinephrine infusions for higher blood pressure target maintenance during cesarean delivery: a randomized sequential allocation trial

YSYongqiang ShiNingxia Medical University RXR XYinchuan First People's Hospital YMYueji MaNingxia Medical University

Key Points

This study aims to find the effective doses (ED90) of phenylephrine and norepinephrine for maintaining maternal blood pressure during cesarean delivery.
Randomized trial with 60 patients aged 18–45 scheduled for cesarean delivery.
Patients were assigned to receive prophylactic infusions of norepinephrine at 0.05 μg/kg/min or phenylephrine at 0.5 μg/kg/min, adjusting as needed.
Maternal adverse events and neonatal outcomes were recorded and analyzed.
ED90 for norepinephrine was determined to be 0.140 μg/kg/min (95% CI: 0.133–0.147).
ED90 for phenylephrine was found to be 1.280 μg/kg/min (95% CI: 1.180–1.380).
No significant difference in adverse events or neonatal outcomes was reported between the groups.

Abstract

Background The international consensus on vasopressors for managing hypotension emphasizes maintaining maternal systolic blood pressure (SBP) during cesarean delivery greater than 90% of the baseline and not below 80%. This study was to determine the ED90 values of prophylactic norepinephrine and phenylephrine infusions under higher blood pressure management target of maintaining maternal SBP at greater than 90% of the baseline. Method Sixty patients aged 18–45 years, who were scheduled to undergo cesarean delivery under spinal anesthesia, were randomly assigned to the norepinephrine group and the phenylephrine group. The first patients in each group were administered prophylactic infusion rates of 0.05 and 0.5 μg/kg/min, respectively. Effectiveness was determined based on whether the current vasopressor infusion dose could achieve the predefined target for maternal SBP management at greater than 90% of the baseline prior to fetal delivery. Subsequently, the vasopressor infusion rate was adjusted incrementally or decrementally by 0.01 and 0.1 μg/kg/min as needed. Additionally, maternal adverse events and neonatal outcomes were systematically recorded and analyzed. Results Through isotonic regression analysis, the ED90 values for prophylactic norepinephrine and phenylephrine infusions under a higher blood pressure management target were estimated to be 0.140 μg/kg/min (95% CI: 0.133–0.147) and 1.280 μg/kg/min (95% CI: 1.180–1.380), respectively. There was no statistically significant difference in the incidence of adverse events or neonatal outcomes between groups. Conclusion When the target was established to maintain the blood pressure of patients at greater than 90% of the baseline prior to delivery in patients undergoing cesarean delivery, the prophylactic infusion rates for norepinephrine and phenylephrine were determined to be 0.140 and 1.280 μg/kg/min, respectively. Clinical Trial Registration Clinicaltrials.gov , NCT06158048.

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