Airway wall mechanics

The dimensions, composition, and stiffness of the airway wall are important determinants of airway cross-sectional area during dynamic collapse in a f orced expiration or when airway smooth muscle is constricted. Under these c ircumstances, airway caliber is determined by an interaction between the fo rces acting to open the airway (parenchymal tension and wall stiffness) and those acting to close it (smooth-muscle force and surface tension at the i nner gas-liquid interface). Experimental measurements and theoretical model s of the airway tube law (relationship between cross-sectional area and tra nsmural pressure) are presented. Data are presented for the elastic propert ies of the wall tissue. Simulations of airway constriction in normal and as thmatic airways are discussed. To the extent possible, comparisons are pres ented between the various models and existing experimental data.