Post-operative vomiting after paediatric strabismus surgery: a comparison of propofol versus sevoflurane anaesthesia

Post-operative nausea and vomiting (PONV) is a significant problem after strabismus surgery. In the absence of any prophylaxis, the incidence of post-opeartive vomiting is 40-60%. Several factors including duration of surgery, use of volatile anaesthetic agents and nitrous oxide for maintenance of anaesthesia, use of opioids for analgesia in the post-opeartive period as well as history of motion sickness or PONV in the child have all been reported to be risk factors. Children belowtwelve years need general anaesthesia for squint surgery to ensure immobility and pain relief. Among the anaesthetic agents, use of inhalational agents(isoflurane, sevoflurane, desflurane, nitrous oxide) have all been implicated in increasing the risk of PONV. In TIVA(totally intravenous anaesthesia) technique, oxygen and are the only gases used and anaesthesia is maintained using an infusion of propofol. This technique has been found to reduce e PONV in other types of surgery . The primary outcome is to compare the incidence of postoperative vomiting in children undergoing strabismus surgery under intravenous versus balanced anaesthesia. The secondary outcome is to compare the incidence of emergence agitation in the two groups. This study is unique in being the first to compare sevoflurane (without nitrous oxide)and propofol  as agents for maintenance of anaesthesia  in squint surgery in children aged 1-12 years. 70 children will be randomized into one of the two groups S or P w, in whom anaesthesia will be maintained using sevoflurane balanced anesthesia or TIVA with propofol respectively. They will be intubated after administration of injection fentanyl 2 µg/kg and atracurium 0.5mg/kg. Both groups will receive ondansetron 0.1mg/kg, dexamethasone 0.1mg/kg intravenously as anti-emetic prophylaxis and paracetamol 15mg/kg intravenously for post-operative analgesia. The intra-operative hemodynamics  like heart rate, blood pressure, total dose of Fentanyl and atracurium as well as the duration of surgery and anaesthesia will be noted. At the end of surgery, the child will be monitored in the post anaesthesia care unit. The emergence delirium will be noted using a PAED (paediatric anaesthesia emergence delirium) score. Any episode of postoperative nausea or vomiting in the 0-2 hour, 2-6 hour and 6-24 hour period will be recorded. Retching is also considered as vomiting. Rescue antiemetic ondansetron 0.1 mg/kg will be administered if there is more than one episode of vomiting. The end point of the study is reached at 24 hour.