The attenuating effect of intraglossal atropine on the oculocardiac reflex

Bradycardia during strabismus surgery is reduced better by intravenous than by intramuscular (deltoid) anticholinergics, but recent studies suggest that injection into the tongue works faster than into the deltoid. We sought to study this using the suppression of the oculocardiac reflex during eye surgery as a parameter.

804 children and adults underwent calibrated extraocular muscle tensioning during controlled, inhalational general anesthesia. A systemic anticholinergic agent was distributed by different routes to patient-subject sub-groups: preoperative oral, or induction intravenous, intramuscular (deltoid) and intraglossal (submucosal at the base of the tongue). A large control group received no anticholinergic.

The control group had an oculocardiac reflex averaging 17.2% heart rate reduction (bradycardia), 6% of whom had greater than a 50% heart rate reduction. This oculocardiac reflex bradycardia was reduced to only a 6.7% heart rate reduction by oral and intradeltoid routes and was essentially eliminated by both intravenous (-2.3%) and intraglossal (-0.9%) routes.

Intraglossal atropine is an effective alternative for oculocardiac reflex prophylaxis when intravenous access is not readily available in strabismus surgery. The intraglossal route is in fact slightly more effective in this regard that the intravenous route per se.