Ephedrine versus ondansetron in the prevention of hypotension during cesarean delivery: a randomized, double-blind, placebo-controlled trial

Background Maternal hypotension is common after spinal anesthesia for cesarean delivery. We compared the effects of prophylactic ephedrine with ondansetron on post-spinal blood pressure. Methods One hundred and sixty-eight term, singleton parturients were enrolled in this prospective, double-blind, placebo-controlled trial. Patients were randomized to receive either prophylactic intravenous ephedrine 10 mg (Group E), ondansetron 8 mg (Group O) or normal saline (Group P) immediately after spinal anesthesia. The primary outcome was maternal blood pressure between spinal block and delivery; secondary outcomes were nausea and vomiting scores, Apgar scores, numbers requiring intraoperative vasoconstrictors and the dose of vasoconstrictors required. Results Fifty-six patients were recruited to each group, but two in Group P were excluded from the analysis owing to protocol violations. There were no significant differences between the groups in maternal systolic, diastolic or mean arterial pressures, or the proportion of patients experiencing hypotension. The proportion of patients in Group E requiring intraoperative ephedrine or any vasoconstrictor (ephedrine and/or norepinephrine) was significantly lower than that in Group P (P=0.023 and 0.034, respectively). The proportion of patients in Group O requiring intraoperative norepinephrine was significantly lower than that in Group P (P=0.02). There was no difference in the proportions of patients in Groups E and O requiring any vasoconstrictors (P=0.34). Conclusions There was no significant difference in maternal blood pressure in women administered prophylactic ephedrine or ondansetron after spinal anesthesia for cesarean delivery compared with placebo. Ephedrine reduced the proportion of patients requiring a rescue vasoconstrictor before delivery.