The association between the oculocardiac reflex and post-operative vomiting in children undergoing strabismus surgery

The oculocardiac reflex (OCR) is a potentially serious complication of ophthalmic surgery which is most commonly elicited during paediatric strabismus surgery. Post-operative vomiting (POV) is also extremely common after such procedures and may result in admission following planned day-case surgery. Although many factors play a part in the occurrence of POV, stimulation of the trigemino-vagal reflex are is thought to explain the particularly high rate of vomiting after strabismus surgery. The OCR and the vaso-vagal response share this neuronal pathway, the bradycardia of the OCR often being the only objective feature of the vaso-vagal response while the patient is anaesthetised. The aim of this study was to investigate the possible association between the occurrence of the OCR and subsequent POV in children undergoing strabismus surgery. We have studied this relationship in 79 children, aged between 1 and 13 years, undergoing strabismus surgery under standardised anaesthetic conditions. A positive OCR was regarded as a drop in heart rate of 10% or more, or the onset of a dysrhythmia. An intraoperative OCR was elicited in 51 (64.6%) of the 79 children, whilst 29 (36.7%) developed POV in the subsequent 24 h period. There was a significant association between a positive intraoperative OCR and POV (p = 0.01): children with a positive OCR were 2.6 times more likely to vomit than those without the reflex. We conclude that there is an association between the occurrence of the OCR and POV and discuss possible preventive strategies.