Relationships among upper airway resistance, area of glottis opening, respiratory flow, and thoracic gas volume were investigated in healthy nonsmokers. Respiratory system resistance was measured with the forced oscillation method and partitioned into upper airway and lower respiratory system resistance by recording lateral pressures at the mouth and in the trachea. Glottis area was obtained by fiberoptic cinelaryngoscopy using. Teflon discs placed on the vocal cords as reference. Mechanical events and movements of the glottis were synchronized by displaying a digital clock on the cine image. Topical anesthesia or manipulation of the airways did not change total respiratory system resistance. Total respiratory system resistance changed curvilinearly with thoracic gas volume. Upper airway resistance showed a linear relationship to thoracic gas volume, but a significant correlation could only be established for extreme volume changes (vital capacity maneuver). Glottis area was larger during panting than during quiet breathing. By assuming a uniform shape of the glottis, upper airway resistance was found to depend on both flow and area of the glottis. Amodification of Rohrer's equation was derived to describe these relationships. Because flow and glottis aperture varied independently, knowledge of both parameters was necessary to predict upper airway resistance for tidal breathing at functional residual capacity.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Applied Physiology Respiratory Environmental and Exercise Physiology|
|State||Published - Jan 1 1977|
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