The effects of increasing depths of anaesthesia on phrenic nerve (PN) activity and hypoglossal nerve (HN) activity during the swallowing reflex elicited by stimulation of the superior laryngeal nerve (SLN) were investigated in 10 cats. Swallowing induced by SLN stimulation always coincided with a characteristic brief burst of PN activity and a large amplitude burst of HN activity. These characteristic responses of PN and HN activities were not influenced by either bilateral vagotomy or neuromuscular blockade, indicating that the characteristic responses of PN and HN activities can be used as indicators of the swallowing reflex in vagotomized and paralysed animals. The results obtained in such animals showed that increasing depth of anaesthesia depressed progressively the swallowing reflex. Detailed analysis of HN activity revealed also that SLN stimulation elicited three different responses of HN activity which had different sensitivities to anaesthesia. However, the characteristic response observed during the swallowing reflex was the most sensitive to increasing depth of anaesthesia.
The effects of changes in PaCO2 and PaO2 on the swallowing reflex were studied in anaesthetized, vagotomized, paralysed and artificially ventilated cats. The swallowing reflex was induced by electrical stimulation of the superior laryngeal nerve (SLN). This initially suppressed activity in the phrenic nerve (PN). The swallowing reflex was then identified by a characteristic brief burst of PN activity and a large amplitude burst of hypoglossal nerve (HN) activity. Steady-state responses to constant SLN stimulation for 60 s were measured at four carbon dioxide tensions (PaCO2 3.9, 5.1, 6.3 and 7.8 kPa) with hyperoxia (PaO2 greater than 51 kPa) and at four values of PaO2 (PaO2 56, 11.3, 6.9 and 4.8 kPa) at a fixed PaCO2 (PaCO2 4.2 kPa). Although both hypercapnia and hypoxia increased the spontaneous respiratory activity in PN and HN, the number of swallows elicited during SLN stimulation was not influenced by PaCO2, whereas a progressive decrease in the number of swallows with decreasing PaO2 was observed consistently. These results indicate that the swallowing reflex is independent of the background respiratory activity and that hypoxia depresses the swallowing reflex, whereas hypercapnia has no effect.
r obstruction n'~tait pas s3v~re et que la saturation artdrielle en oxyg~ne se maintenait au dessus de 80pour cent. Nous avons pu intuber la trachde de l' enfant apr~s une induction par anesth3siques inhales en ventilation spontande. Cette technique et les moniteurs utilis~s peuvent ainsi ~tre utiles dans des cas d'obstruction haute des voles respiratoires.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.