title: Relative contribution of various airway protective mechanisms to prevention of aspiration during swallowing.
abstract: Deglutitive airway protective mechanisms include glottal closure, epiglottal descent, and anterosuperior displacement of the larynx. Aspiration of swallowed material may occur during the pre-, intra-, or postpharyngeal phase of swallowing. Our objectives were to determine the relative contribution of the airway protective mechanisms during each phase of swallow in 14 decerebrated cats before and after suprahyoid myotomy, epiglottectomy, and unilateral cordectomy. After myotomy, superior excursions of the hyoid, thyroid, and cricoid cartilages and anteroposterior diameter of maximum upper esophageal spincter (UES) opening were significantly diminished, but the incidence of pharyngeal residue significantly increased (P < 0.05). No aspiration was observed in the predeglutitive period. After myotomy, the incidence of aspiration significantly increased in both intra- and postdeglutitive periods. Epiglottectomy did not alter aspiration incidence, but unilateral cordectomy resulted in a 100% incidence of intra- and postdeglutitive aspiration. In conclusion, glottal closure constitutes the primary mechanism for prevention of intra- and postdeglutitive aspiration, but laryngeal elevation may assist this function. Bolus pulsion without laryngeal distraction can open the UES, but at risk of aspiration due to decreased pharyngeal clearance. The epiglottis provides no apparent airway protection during any phase of swallowing.
authors.affiliation: Medical College of Wisconsin Dysphagia Institute, Division of Gastroenterology and Hepatology, and Department of Medicine, The Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Bidyut K
authors.initials: BK
authors.lastname: Medda
authors.forename: Mark
authors.initials: M
authors.lastname: Kern
authors.forename: Junlong
authors.initials: J
authors.lastname: Ren
authors.forename: Pengyan
authors.initials: P
authors.lastname: Xie
authors.forename: Seckin O
authors.initials: SO
authors.lastname: Ulualp
authors.forename: Ivan M
authors.initials: IM
authors.lastname: Lang
authors.forename: Reza
authors.initials: R
authors.lastname: Shaker
mesh_terms: D000818:Animals; D002415:Cats; D003413:Cricoid Cartilage / Q000502:physiology; D003679:Deglutition / Q000502:physiology*; D004825:Epiglottis / Q000502:physiology / Q000601:surgery; D004947:Esophagus / Q000000981:diagnostic imaging / Q000502:physiology; D005260:Female; D006928:Hyoid Bone / Q000502:physiology; D001239:Inhalation / Q000502:physiology*; D008297:Male; D010614:Pharynx / Q000502:physiology; D011859:Radiography; D013957:Thyroid Cartilage / Q000502:physiology; D014132:Trachea / Q000000981:diagnostic imaging / Q000502:physiology; D014827:Vocal Cords / Q000502:physiology / Q000601:surgery