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BACKGROUND: Spinal anesthesia is the preferred anesthetic technique for cesarean deliveries. Postoperative nausea and vomiting (PONV) and pruritus occur in up to 80% and 83% of patients, respectively, after cesarean delivery with intrathecal opioids. Ondansetron is the recommended medication for PONV prophylaxis, but palonosetron, a second-generation 5-HT3 receptor antagonist, has a higher receptor affinity and a longer half-life. However, studies on palonosetron use in cesarean deliveries are limited. This study aimed to determine whether palonosetron was more effective than ondansetron in preventing intrathecal morphine-induced PONV and pruritus in cesarean deliveries. METHODS: Parturients who underwent cesarean delivery under spinal anesthesia were randomized into 3 groups: P (palonosetron 0.075 mg), O (ondansetron 4 mg), and N (normal saline). The study drug was intravenously administered after the umbilical cord was clamped. The primary outcome measures were the 48-hour incidence of PONV and pruritus. The secondary outcome measures were the PONV and pruritus scores at the postanesthesia care unit (PACU) and ward, rescue medications, satisfaction scores, and adverse events. Ordinal data were analyzed using the Kruskal-Wallis test. Continuous and categorical data were analyzed using a 1-way analysis of variance, Kruskal-Wallis test, and Pearson's χ 2 test, respectively. A value of P < .05 was considered significant. Post hoc analysis pairwise comparisons with Bonferroni correction were also performed. RESULTS: Overall, 300 parturients were enrolled, and 297 parturients completed the study. One patient in the P group and 2 in the O group were excluded because of conversion to general anesthesia after failed spinal anesthesia. The baseline patient characteristics were comparable between the groups. The PONV incidence rates in the P, O, and N groups were 26.3% (95% confidence interval CI, 17.4-35.1), 34.7% (95% CI, 25.1-44.3), and 50.0% (95% CI, 40.0-59.9), respectively ( P = .002). The incidence rates of pruritus in the P, O, and N groups were 69.7% (95% CI, 60.5-78.9), 76.5% (95% CI, 67.9-85.1), and 87.0% (95% CI, 80.3-93.7), respectively ( P = .013). Pairwise comparisons revealed significantly lower incidences of PONV and pruritus in the P group than in the N group ( P < .001 and P = .003, respectively). However, no significant differences were observed between the P and O groups or between the O and N groups. Additionally, the P group required significantly less nalbuphine rescue for pruritus than the N group ( P = .004 and P = .005 for the PACU and ward, respectively). PONV rescue, satisfaction scores, and adverse events were not significantly different among the 3 groups. CONCLUSIONS: Palonosetron effectively prevents intrathecal morphine-induced PONV and pruritus during cesarean delivery. However, the efficacy of palonosetron is not significantly different from that of ondansetron.
Worravitudomsuk et al. (Wed,) studied this question.