5-HT3 Receptor Antagonists Cut Nausea, Vomiting in C-Section


SAN FRANCISCO — Administering the 5-HT3 receptor antagonists ondansetron or granisetron to women undergoing cesarean delivery with neuraxial anesthesia significantly reduces intraoperative and postoperative nausea and vomiting, compared with placebo, according to a meta-analysis of nine randomized, double-blind trials.

Intraoperative nausea and vomiting are “emerging in obstetrical anesthesia practice as a major problem,” Dr. Terrence K. Allen, an anesthesiologist at Duke University, Durham, N.C., noted. “It's different from the general surgical population because, obviously, those patients are asleep,” he said.

Previous systematic reviews have shown the efficacy of these agents in reducing nausea and vomiting after surgery with general anesthesia. The nine individual studies of 5-HT3 receptor antagonists in women who were administered neuraxial anesthesia for cesarean delivery produced inconsistent results, so the researchers grouped them in a meta-analysis, Dr. Allen said in a poster presentation at the annual meeting of the American Society of Anesthesiologists.

The medication was administered intraoperatively following clamping of the umbilical cord or delivery of the baby in eight studies in the meta-analysis, and postoperatively in one study. Dr. Allen and his coinvestigator, Dr. Ashraf S. Habib, combined the data on ondansetron and granisetron and the dose ranges used in the studies because recent consensus guidelines report no evidence of differences in efficacy between these subgroups.

Results showed that the 5-HT3 receptor antagonists significantly reduced the relative risks for nausea and vomiting, compared with placebo. They reduced the risk for intraoperative nausea by 38%, the risk for intraoperative vomiting by 46%, the risk for postoperative nausea by 49%, and the risk for postoperative vomiting by 49%, he reported.

Nausea and vomiting make surgery and anesthesia a little more unpleasant, Dr. Allen said. The study's results have affected practice at his institution.

Dr. Allen and Dr. Habib, also of Duke University, have no financial relationships with the companies that make the medications studied.


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