title: Direct measurement of subglottic air pressure while swallowing.
abstract: OBJECTIVE
  The subglottic pressure theory for swallowing asserts that laryngeal mechanoreceptors have a role in the regulation of swallowing function. The primary purpose of this study was to determine if subglottic air pressure is generated during swallowing in a healthy, nontracheostomized person.
  
  
  METHODS
  This pilot investigation used a prospective, repeated-measures design in a single subject. Direct measurement of subglottic air pressure was obtained through percutaneous puncture of the cricothyroid membrane. Swallows were timed with four randomly assigned lung volumes: total lung capacity, tidal volume, functional residual capacity (FRC), and residual volume.
  
  
  RESULTS
  Lung volumes above FRC generated positive subglottic pressure during the swallow, whereas lung volumes below FRC generated consistently negative subglottic pressures. The degree and polarity of the pressure was directly related to lung volume at the time of the swallow.
  
  
  CONCLUSIONS
  These findings illustrate that during normal swallowing, positive subglottic air pressure is likely present. Previously, subglottic air pressure during swallowing had been measured in tracheostomy patients only.
authors.affiliation: Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. Grossrd@upmc.edu
authors.forename: Roxann Diez
authors.initials: RD
authors.lastname: Gross
authors.forename: Kimberly M
authors.initials: KM
authors.lastname: Steinhauer
authors.forename: David J
authors.initials: DJ
authors.lastname: Zajac
authors.forename: Mark C
authors.initials: MC
authors.lastname: Weissler
mesh_terms: D000328:Adult; D000399:Air Pressure; D000403:Airway Resistance; D003679:Deglutition / Q000502:physiology*; D004576:Electromyography; D005931:Glottis / Q000502:physiology*; D006801:Humans; D010865:Pilot Projects; D011446:Prospective Studies; D012016:Reference Values; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D014109:Total Lung Capacity