Single bolus of intravenous ketamine for anesthetic induction decreases oculocardiac reflex in children undergoing strabismus surgery

Background: Oculocardiac reflex (OCR) is a major complication of pediatric strabismus surgery. The aim of the present study was to determine whether a single bolus of intravenous (i.v.) ketamine for anesthetic induction can decrease OCR in children undergoing strabismus surgery. Methods: One hundred and twenty healthy children undergoing strabismus surgery were allocated to three groups using double-blind randomization. Anesthesia was induced with propofol 3 mg/kg in Group P, ketamine 1 mg/kg in Group K1, or ketamine 2 mg/kg in Group K2. Anesthesia was maintained with 3% sevoflurane in 50% N2O/O-2 in all patients. The baseline heart rate was obtained 30 s prior to the first traction of the extraocular muscle (EOM). OCR was defined as a development of arrhythmia or a decrease of more than 20% of the baseline heart rate during EOM traction. Results: The incidence of OCR was significantly lower in the ketamine groups (4/40 and 1/40 in Group K1 and K2, respectively) compared with the propofol group (14/40). Conclusion: A single bolus of i.v. ketamine 1 or 2 mg/kg for anesthetic induction results in a lower incidence of OCR than propofol when combined with sevoflurane for maintenance in children undergoing strabismus surgery.