THE OCULOCARDIAC REFLEX
Traction on extraocular muscles, pressure on the eyeball, administration of a retrobulbarblock, and trauma to the eye can elicit a wide variety of cardiac dysrhythmias ranging from bradycardia and ventricular ectopy to sinus arrest or ventricu-lar fibrillation. This reflex consists of a trigemi-nal (V1) afferent and a vagal efferent pathway. The oculocardiac reflex is most commonly encounteredin pediatric patients undergoing strabismus surgery, although it can be evoked in all age groups and dur-ing a variety of ocular procedures, including cata-ract extraction, enucleation, and retinal detachment repair. In awake patients, the oculocardiac reflex may be accompanied by nausea.
Routine prophylaxis for the oculocardiac reflex is controversial. Anticholinergic medication is often helpful in preventing the oculocardiac reflex, and intravenous atropine or glycopyrrolate immedi-ately prior to surgery is more effective than intra-muscular premedication. However, anticholinergic medication should be administered with caution to any patient who has, or may have, coronary artery disease, because of the potential for increase in heart rate sufficient to induce myocardial ischemia. Ventricular tachycardia and ventricular fibrillation following administration of anticholinergic medica-tion has also been reported. Retrobulbar blockade or deep inhalational anesthesia may also be of value in preempting the oculocardiac reflex, although administration of a retrobulbar block may itself ini-tiate the oculocardiac reflex.
Management of the oculocardiac reflex when it occurs includes: (1) immediate notification of the surgeon and temporary cessation of surgical stimu-lation until heart rate increases; (2) confirmation of adequate ventilation, oxygenation, and depth of anesthesia; (3) administration of intravenous atropine (10 mcg/kg) if bradycardia persists; and in recalcitrant episodes, infiltration of the rectus muscles with local anesthetic. The reflex eventually fatigues (self-extinguishes) with repeated traction on the extraocular muscles.