Comparison of Intravenous Lidocaine versus Hyoscine on Prevention of Oculocardiac Reflex in Strabismus Surgery

Purpose: Oculocardiac reflex (OCR) is a frequent event during strabismus surgery. The aim of this study is to compare the preventive effect of intravenous lidocaine and hyoscine on OCR. Methods: This prospective, randomized clinical trial was performed on 75 patients (5-63 years old) underwent strabismus surgery. Patients divided randomly into three groups. Intravenous hyoscine (0.2 mg/kg), lidocaine (1.5 mg/kg) and distilled water were injected before induction with propofol for each group respectively under standard monitoring. Heart rate, blood pressure and/or cardiac dysrrythmia were recorded immediately before/after injection and muscle hooking. Decrease of heart rate more than 20%, hypotension (decrease more than 20% in systolic or diastolic pressure) or any cardiac dysrrythmia were defined as OCR. Results: One hundred and thirty-six muscles were hooked during strabismus surgery. OCR was observed in 44 hooked muscles (32.3%). Reflex was observed in hyoscine (34.2%), lidocaine (24.9%) and control (40.9%) groups (p=0.12). The most stretched muscles which caused OCR were medial rectus (56.8%) and lateral rectus (36.3%) muscles. OCR was greater in patients with age between 5-10 years (56%). Conclusion: Intravenous lidocaine and N-buthylbromide hyoscine both could reduce OCR occurrence but the difference was not statistically significant compared to the control group. OCR was seen greater in young patients (5-10 years old). Some patients (specially children) need intervention to restore normal condition.