Active upper airway closure during induced @entity2417 in XXXX is complete at the laryngeal level only.

@entity2507 @entity2417 @entity742 @entity386
We tested the hypotheses that active upper airway closure during induced @entity2417 in nonsedated @entity742 1). is complete and occurs at the laryngeal level and 2). is not due to stimulation of the superior laryngeal nerves (SLN). Five newborn @entity742 were surgically instrumented to record thyroarytenoid (TA) muscle (glottal constrictor) electromyographic (EMG) activity with supra- and subglottal pressures. @entity2417 were induced before and after SLN sectioning in the five @entity742 . A total of 174 @entity386 were induced, 116 before and 58 after sectioning of the internal branch of the SLN (iSLN). Continuous TA EMG activity was observed in 88% of @entity386 before iSLN section and in 87% of @entity386 after iSLN section. A transglottal pressure different from zero was observed in all @entity386 with TA EMG activity, with a mean subglottal pressure of 4.3 +/- 0.8 cm @entity2507 before and 4.7 +/- 0.7 cm @entity2507 after iSLN section. Supraglottal pressure was consistently atmospheric. Sectioning of both iSLNs had no effects on the results. We conclude that upper airway closure during induced @entity2417 in @entity742 is active, complete, and occurs at the glottal level only. Consequently, a positive subglottal pressure is maintained throughout the @entity386 . Finally, this complete active glottal closure is independent from laryngeal afferent innervation.
