U. Braun et al., IS THERE A CHOLINERGIC AND AN ADRENERGIC PHASE OF THE OCULOCARDIAC REFLEX DURING STRABISMUS SURGERY, Acta anaesthesiologica Scandinavica, 37(4), 1993, pp. 390-395
We investigated the counterregulatory effect of the oculocardiac refle
x (OCR) in 25 infants and children during strabismus surgery under thr
ee experimental conditions. In group 1, a series of measurements were
recorded when the OCR was elicited by traction. The beat-to-beat heart
rate reduction ranged from -26 to -64 beats/min (median: -46 beats/mi
n). Constant traction increased heart rate in all patients from +23 to
+50 beats/min (median: +30.5; P<0.001). After a sudden release of the
stimulation, heart rate rose further from +6 to +40 beats/min (median
: +15; P<0.001). In group 2, atropine (0.01 mg/kg) was administered 3-
4 min prior to the same manipulations as in group 1. Constant traction
changed heart rate from -1 to +20 beats/min (median: +4.5; P<0.01). I
n group 3, a retrobulbar blockade suppressed the OCR and the counterre
gulation completely. These findings indicate that there is an active c
ounterregulatory process which maintains heart rate during traction at
the extraocular muscles after the bradycardic reflex has been initiat
ed. The bradycardia and the counterregulation may be referred to as ch
olinergic and adrenergic phrases of the OCR. Atropine eliminates the c
holinergic phase. Our study indicates that may be receptors and affere
nt fibres for both phases, which can be blocked by local anaesthetics.