Prophylactic ondansetron in prevention of postoperative nausea and vomiting following pediatric strabismus surgery - A dose-response study

Background: This study evaluated the antiemetic effectiveness, dose-response, and clinical usefulness of prophylactic ondansetron in the prevention of postoperative nausea and vomiting (PONV) in children undergoing strabismus repair. Method: The authors observed 180 children, American Society of Anesthesiologists physical status I or II, 2-12 yr of age, who were undergoing strabismus repair. After induction of anesthesia with halothane and nitrous oxide in oxygen or intravenous thiopental, children received either placebo (saline) or intravenous ondansetron in doses of 25, 50, 75, 100, and 150 mu g/kg (n = 30). The trachea was intubated and ventilation was controlled. Perioperative analgesic and fluid requirements were standardized. Episodes of nausea and vomiting were recorded for the first 24 h postoperatively. Data such as nonsurrogate (parental satisfaction scores and duration of postanesthesia care unit stay) and therapeutic (numbers needed to prevent and harm) outcome measures were collected. Results: The incidences of PONV in the placebo and 25-, 50-, 75-, 100-, and 150-mu g/kg ondansetron groups were 83, 77, 47, 30, 30, and 27%, respectively. The incidence was less in the 75- (P = 0.002), 100- (P = 0.002), and 150-mu g/kg (P < 0.001) ondansetron groups compared with placebo. Duration of stay in the postanesthesia care unit was shorter in the 75-, 100-, and 150-mu g/kg ondansetron groups (P < 0.002) compared with the placebo group. Parental assessment scores for the child's perioperative experience and the positive number needed to prevent PONV were also better and favorable in the 75-, 100-, and 150-mu g/kg ondansetron groups compared with the placebo group. The incidence (P > 0.99) and severity (P = 0.63) of PONV were similar in the 75- and 150-mu g/kg ondansetron groups. Surrogate, nonsurrogate, and therapeutic outcome measures revealed that 75 mu g/kg ondansetron provided the same benefits as did 100 and 150 mu g/kg. Conclusion: The routine prophylactic use of ondansetron at a dose of 75 mu g/kg is as effective as 150 mu g/kg in preventing PONV and improving the "true" outcome measures after strabismus repair in children.