EFFECTS OF ONDANSETRON IN THE PREVENTION OF POSTOPERATIVE NAUSEA AND VOMITING IN CHILDREN

Background: Postoperative nausea and vomiting (PONV) is a commonly obs erved adverse effect of general anesthesia. Recently, ondansetron, a n ew serotonin, (5-hydroxytryptamine(3)) receptor antagonist was shown t o be effective in the prophylaxis and prevention of chemotherapy-induc ed nausea and vomiting in children and adults as well as of PONV in ad ults. The aim of the current study was to evaluate the capacity of ond ansetron to prevent PONV in pediatric patients. Methods: Two hundred c hildren (132 boys and 68 girls) 2-10 yr of age received general inhala tional anesthesia for surgical procedures (the extremities; ear, nose, and throat; inguinal hernia and phimosis; and dentistry) of an expect ed duration of less than 90 min. This study was divided into two phase s: prophylaxis and rescue treatment. For prophylaxis, patients were ra ndomly assigned to two groups: one group received an intravenous injec tion of 0.1 mg/kg ondansetron, and the other group received a placebo before surgical incision under double-blind conditions. For rescue tre atment, only placebo patients were included; as a rescue medication th ey received an intravenous injection of 0.1 mg/kg ondansetron or 0.02 mg/kg droperidol according to a prestudy randomization under double-bl ind conditions. Incidence and severity of PONV (PONV score 0 = no naus ea and no retching; 1 = complaining of sickness and retching; 2 = vomi ting one or two times in 30 min; 3 = vomiting more than two times in 3 0 min) was recorded over a 4-h period in the postanesthesia care unit. Within 72 h of the procedure, a follow-up nurse interviewed the paren ts for late-onset nausea in the children. Results: With regard to prop hylaxis, 10%, of patients receiving ondansetron had PONV during the 4- h observation period versus 40% of those receiving placebo (P < 0.001) . The incidence of vomiting alone (PONV score greater than or equal to 2) was 5% and 25%, respectively (P < 0.001). There were no significan t differences between ondansetron and droperidol in the treatment of P ONV. However, at the end of the 4-h period, ondansetron patients were less sedated than were patients who had received droperidol (P < 0.01) . Interviews with parents could be performed for 143 of 200 children ( 76 ondansetron and 67 placebo). Twenty-four children (15 ondansetron a nd 9 placebo) showed late-onset PONV after the 4-h observation period but within 24 h of the procedure (19.7% vs. 13.4%; P not significant). Conclusions: Ondansetron is effective in the prevention of PONV in pe diatric patients for the first 4 h after general anesthesia. Lower sed ation scores with ondansetron compared with droperidol may be an advan tage, especially in ambulatory surgery. However, the incidence of late -onset PONV (>4-24 h) was not influenced by prophylactic treatment wit h one dose of ondansetron preoperatively.