Comparison of Single Bolus Dexamethasone, Ondansetron, and Placebo for Prophylactic Antiemetic after Intrathecal Morphine for Caesarean Section: a Prospective Randomized Double-Blind Study

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Saowaluk Sotananan


Background: High incidences of nausea and vomiting (30-65%) after intrathecal morphine for patients undergoing caesarean section leading to patient discomfort, delayed mother-to-baby bonding, and aggravated postoperative pain could result in wound dehiscence, aspiration, or dehydration. This study aimed to compare the efficacy of the antiemetic effect between intravenous (IV) dexamethasone 5 mg, IV ondansetron 8 mg and a placebo in patients receiving intrathecal morphine for caesarean section. Methods: A prospective randomized double-blind study was conducted at Somdetphraphutthaloetla Hospital. Patients undergoing elective caesarean section were randomized to receive IV dexamethasone, IV ondansetron or a placebo. The primary outcome was an incidence of postoperative nausea in the first 24 h. Results: A total of 90 patients were analyzed by the intention to treat method. There was no difference in demographic data among groups. The incidence of postoperative nausea in 24 h as the primary outcome was 6.7% in the dexamethasone group, 6.7% in the ondansetron group, and 20.0% in the placebo group. There was no statistical difference in postoperative nausea in 24 h among groups. Incidences of postoperative vomiting, shivering, and pruritus within 24 h, postoperative tramadol consumption, postoperative pain score showed no significant differences. Adverse effects were not found in all groups. Conclusion: Both dexamethasone and ondansetron could potentially decrease the incidence of postoperative nausea within 24 h after receiving 0.2 mg of intrathecal morphine compared with a placebo effect. Although the reduction of incidence outcome had an NNT of 7.5, the result was not statistically significant.

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