[Interaction of swallowing and control of breathing]

Although it is well known that swallowing interacts with respiration, information about the relationship between respiration and swallowing is limited. In this paper we described the interaction between swallowing reflex and respiration. In experimental animals, reflex swallowing can be elicited readily by electrical stimulation of the superior laryngeal nerve, and the effects of depressants on this reflex can be assessed by changes in the latency of responses and the number of swallows elicited. The swallowing reflex is independent of the background respiratory activity and a decrease in PaO2 depresses the swallowing reflex, whereas changes in Paco2 have no effect. In human subjects, the swallowing reflex can be induced by injections of a small amount of water into the pharynx. Like the responses in animals, the responses in humans can be assessed by changes in the latency of responses and the number of swallows. Using this technique, we evaluated the effects of nasal CPAP on the swallowing reflex. Our results showed that nasal CPAP remarkably depresses the swallowing reflex.