Comparison of Two Anesthetic Techniques (Propofol with and without Nitrous Oxide) on Oculocardiac Reflex and Postoperative Nausea and Vomiting in Pediatric Strabismus Surgery

BACKGROUND : Intraoperative oculocardiac reflex (OCR) and postoperative nausea and vomiting (PONV) are common problems of pediatric strabismus surgery. Propofol is thought to increase the incidence of OCR in spite of profound antiemetic effect. The goal of this study was to assess, in pediatric strabismus surgery, the incidence of OCR and PONV in a propofol with and without nitrous oxide (N2O) anesthesia. METHODS : Children (1~14 yr.'s) undergoing strabismus surgery as in patients were randomly allocated to two anesthetic techniques: propofol with 60% N2O and propofol with air instead of N2O. All children received iv fentanyl 2 microgram/kg, atropine 0.015 mg/kg and 1% lidocaine 1.5~2 ml before propofol 2.5 mg/kg injection. Anesthesia was maintained with three stage infusion method of propofol with and without N2O by groups after intubation with atracurium 0.4 mg/kg. A significant OCR was defined as an acute decrease in heart rate of 20% or greater associated with traction on an ocular muscle. RESULTS : Data on 224 children were analyzed. An intraoperative OCR was elicited in 41 (36.9%) of the 111 children in the N2O group and in 66 (58.4%) of the 113 children in Air group, while 14 (12.6%) and 12 (10.6%) developed PONV in the N2O group and the Air group in the subsequent 24 hr. period. The OCR was more frequent during medial rectus muscle correction (62.5%) than in lateral rectus muscle correction (39.5%). There was no significant correlation between OCR and PONV. CONCLUSIONS : We conclude that propofol with N2O anesthesia was effective in reducing the incidence of intraoperative OCR with a similarly excellent postoperative antiemetic effect in pediatric strabismus surgery compared to propofol without N2O anesthesia.ope