The coordinated interaction of breathing and swallowing which is developed by 32-34 weeks human gestation is reflex in nature. Chenosensitivity of the laryngeal area can be shown to influence this interaction. A relationship between disturbances of this coordination, newborn apnea and SIDS is postulated. A laryngeal reflex which is elicited by chemical stimulation has been studied in a standardized manner in 18 newborn lambs using acute and chronic preparations. Water, various concentrations of salts and foreign (e.g. formula) solutions, applied above a tracheostomy. cause reflex hypoventilation or apnea, rapid swallowing, hypertension and blood flow redistribution (increase in carotid artery flow, decreased flow in descending aorta), with variable bradycardla. Normal ventilation can be restored by application of 154meq/l saline. We have demonstrated that 1) the reflex is not all or none, but graded and dose-response in type with respect to all components: stimulus, response and recovery. 2) cardiovascular changes are an integral part of the reflex and not due to hypoxia 3) laryngeal sensitivity and the reflex can be altered by chemical modification of taste reception (by potassium gynmenate and miraculin). It is concluded that:(1)Taste receptors present in the laryngeal area are also the likely receptor for mediation of the reflex; (2) this is a useful model to study newborn apnea and (3) the reflex may be involved in the etiology of SIDS.
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Kovar, I., Selstam, U., Catterton, W. et al. LARYNGEAL CHEMOREFLEX - NEWBORN APNEA AND SUDDEN INFANT DEATH SYNDROME (SIDS). Pediatr Res 11, 536 (1977). https://doi.org/10.1203/00006450-197704000-00996