Elastic characteristics of the airway wall.
To examine the elastic behavior of the upper airway, we obtained pressure-area plots from data gathered from acoustic images of the airway and measurements of mouth pressure during tidal breathing in 10 adult human volunteers (dA/dP). These plots revealed both tidal hysteresis and a change in slope as a function of distance along the airway. The slope of the regression line of the dA/dP plots decreased from the pharyngeal region to the trachea and became 0 at the thoracic inlet, the location of which was independently assessed. In most subjects the slope became negative distal to the thoracic inlet. Correlation coefficients between pressure and area approached 1 in the pharyngeal region and 0 at the thoracic inlet. When subjects breathed against a small resistive load (10 cmH2O.1(-1).s) pharyngeal, extrathoracic, and intrathoracic pressure-area plots were exaggerated but the slope at the thoracic inlet was unchanged. We conclude that this pressure-area characteristic defines regional differences in upper airway elasticity and delineates the transition point between the intra- and extrathoracic airways.
Fouke
J M
JM
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106.
Wolin
A D
AD
Strohl
K P
KP
Galbraith
G M
GM
D000162:Acoustics; D004548:Elasticity; D005260:Female; D006801:Humans; D008297:Male; D010614:Pharynx / Q000502:physiology; D011312:Pressure; D012119:Respiration; D012143:Respiratory Physiological Phenomena; D014132:Trachea / Q000502:physiology