Antiemetics added to phenylephrine infusion during cesarean delivery: a randomized controlled trial.

To estimate whether the addition of metoclopramide or its combination with ondansetron to a prophylactic phenylephrine infusion provides improved intraoperative nausea and vomiting prophylaxis compared with phenylephrine infusion alone. Women scheduled for elective cesarean delivery were randomized to one of three groups: placebo (placebo plus placebo); metoclopramide (metoclopramide 10 mg plus placebo); or combination (metoclopramide 10 mg plus ondansetron 4 mg). The first study drug was administered before spinal placement and the second was administered after cord clamping. Spinal anesthesia was standardized. The primary outcome was intraoperative nausea and vomiting. Three-hundred patients completed the study in two centers. Intraoperative nausea and vomiting occurred in 49%, 31%, and 23% of patients in the placebo, metoclopramide, and combination groups, respectively (P<.001). There was a significant difference between the two centers in exteriorization of the uterus (93% compared with 39%; P<.001) and intraoperative nausea and vomiting rates (47% compared with 20%; P<.001). In a multivariable model adjusting for center, exteriorization of the uterus, age, and hypotension, intraoperative nausea and vomiting were significantly lower in the metoclopramide and combination groups compared with placebo (odds ratio [OR] 2.34, 95% confidence interval [CI] 1.24--4.42; P=.001 and OR 4.06, 95% CI 2.06--7.97; P<.001, respectively). Postoperative nausea and vomiting were reduced with the combination compared with placebo at 2 hours (39% compared with 20%; P<.017), but not at 2-6 hours or at 6-24 hours. Metoclopramide with ondansetron reduced intraoperative nausea and vomiting and early postoperative nausea and vomiting compared with placebo. Metoclopramide alone also decreased intraoperative but not postoperative nausea and vomiting. Surgical factors contributed to a significant difference in intraoperative nausea and vomiting between the two centers.