Effect of timing of ondansetron administration on incidence of postoperative vomiting in paediatric strabismus surgery

This prospective, randomized, double-blinded study evaluated the effect of the timing of ondansetron administration an its antiemetic efficacy in chil dren undergoing elective strabismus surgery. One hundred and twenty childre n aged one to 15 years, ASA physical status 1 or 2, were randomly allocated to receive intravenous ondansetron 100 mu g/kg either at induction (Group I) or at the end of the surgery (Group 2). All patients had general anaesth esia induced and maintained with nitrous oxide and halothane, muscle relaxa tion with vecuronium, endotracheal intubation, reversal with neostigmine an d glycopyrrolate, and pethidine 0.5 mg/kg analgesia. Episodes of nausea and vomiting were evaluated at 0 to 2, 2 to 6 and 6 to 24 hour intervals by a blinded observer Demographic data, duration of anaesthesia, type of surgery , incidence of previous postoperative nausea or vomiting and motion sicknes s and number of patients who developed oculocardiac reflex requiring atropi ne treatment were similar in both groups. The incidence of emesis in the fi rst 24 hours following surgery was similar in both groups (35% Group 1, 33. 3% Group 2, P = 1.00). Severity of emesis (median number of emetic episodes , rescue antiemetic requirement and mean time to the onset of first episode of emesis) and mean time to discharge from the post anaesthesia care unit were also similar in the two groups. We conclude that the timing of ondanse tron administration either before or after the surgical manipulation of ext raocular muscles had similar antiemetic efficacy following strabismus surge ry in children.