Randomised double-blinded comparison of phenylephrine vs ephedrine for maintaining blood pressure during spinal anaesthesia for non-elective Caesarean section

Abstract

In a randomised, double-blinded study, we compared boluses of phenylephrine 100 μg with ephedrine 10 mg for treating hypotension (systolic blood pressure < 100 mmHg) in 204 patients having non-elective Caesarean section under spinal anaesthesia. Umbilical arterial (UA) and venous (UV) pH and base excess were similar between groups. In the ephedrine group, UA lactate concentration was higher (median 2.6 [interquartile range 2.3-3.3] vs 2.4 [1.9-3.0] mmol.l-1p = 0.002) and UV lactate concentration was higher (2.5 [2.2-3.2] vs 2.3 [1.9-2.8] mmol.l-1p = 0.016) and more patients had nausea or vomiting (12.7% vs 3.9%, p = 0.02). Clinical neonatal outcome was similar. Of the protocol-compliant patients (n = 148), UA Po2 and UV Po2 were lower in the phenylephrine group although oxygen content was similar. We conclude that phenyl-ephrine and ephedrine are both suitable vasopressors for use in non-elective Caesarean sections. © 2008 The Association of Anaesthetists of Great Britain and Ireland.