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

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. 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. 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%). 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.