Three initial prophylactic phenylephrine infusion rates and physician interventions in patients with preeclampsia...

Patients with preeclampsia have greater sensitivity to vasopressors and require lower doses than patients without preeclampsia. The aim of the current study was to compare the number of required physician interventions using three initial prophylactic phenylephrine infusion rates titrated to maintain systolic blood pressure close to baseline values.

In this randomised, controlled, double-blind trial, 102 patients with preeclampsia undergoing caesarean delivery under spinal anaesthesia were randomised to one of three prophylactic phenylephrine infusion rates: 15 µg/min, 25 µg/min, or 35 µg/min. The rate was titrated to maintain systolic blood pressure within 10% of baseline values. The primary outcome was the number of physician interventions; secondary outcome measures included the incidence of hypertension, hypotension and bradycardia, total phenylephrine dose, neonatal outcomes, and maternal complications.

The median [interquartile range] number of physician interventions was 6.5 [4-9], 6 [4-7.5] and 6.5 [4-9], respectively, for initial infusion rates of 15, 25, and 35 µg/min (P = 0.831). The total phenylephrine dose was greater with higher infusion doses (P < 0.001). No patient had bradycardia, and one patient had hypertension. Nineteen patients each in groups starting at 15 µg/min and 25 µg/min, and 22 patients starting at 35 µg/min developed hypotension (P = 0.695). Neonatal outcome and maternal complications were not different among groups.

All three infusion regimens required a similar number of physician interventions to maintain systolic blood pressure close to the baseline. A starting dose of 15 µg/min may be considered in this patient population.

CTRI/2023/08/055926; registered on 1st August 2023.