Background:

Subarachnoid anesthesia is the most common technique for cesarean section and coadjuvant opioids such as morphine and fentanyl have adverse events, predominantly nausea and vomit. A randomized, placebo-controlled trial was performed to evaluate the prophylactic effect of ondansetron and dexamethasone on these events.

Objective:

To establish the efficacy of ondansetron and dexamethasone in nausea and vomit prophylaxis in patients undergoing cesarean section.

Method:

A sample of 300 pregnant women was randomized in 3 groups: dexamethasone 4 mg, ondansetron 4 mg, and placebo. Standardized dose of 9 mg of bupivacaine at 0,5% 100 mcg of morphine and 25 mcg of intratechal fentanyl were administered to all patients. Both dexamethasone and ondansetron were compared against placebo. Emergency cesarean section, ASA III and allergic patients to any study drugs were excluded. Nausea and vomiting were evaluated intraoperative, 2, 6 and 24 hours after anesthesia, with a significance level α of 0,05.

Results:

On dexamethasone group the RR for vomit was 0,46 (CI 95% 0,28 to 0,76) and 0,79 (CI 95% 0, 64-0,96) for nausea. On the ondansetron group, it was 0.41 (CI 95% 0,24- 0,69) for vomit and 0,75 (CI 95% 0,67 a 0,84) for nausea. The severity of nausea was statistically lower on the ondansetron group through the entire follow-up. There was no nausea after 6 hours in the dexamethasone group.

Conclusions:

Both dexamethasone and ondansetron showed efficacy as a prophylactic treatment against the onset of nausea and vomit in patients undergoing cesarean section with subarachnoid anesthesia and neuroaxial opioids. Trial registration: (ISRCTN 57227250). MÉD.UIS. 2018;31(1):31-8.

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