STRUCTURE AND FUNCTION IN FIBROSING ALVEOLITIS

Lung volumes, maximal expiratory volume and flows, elastic recoil pres sure, and impedances at various levels of the bronchial tree, as well as tissue impedance, were measured in 13 human lungs that demonstrated generalized fibrosis at autopsy. After fixation, mean internal chord of air spaces (L(ma)), transsection length of the alveolar walls (L(mw )), and internal diameter (($) over bar d) and density of membranous b ronchioles (n/cm(2)) were determined in the same lungs by use of morph ometric techniques. The results of functional and structural measureme nts were correlated and compared with measurements obtained similarly in 10 normal lungs. This study shows that the functional alterations t ypical for fibrosing alveolitis can be attributed to the replacement o f part of the parenchyma by fibrous tissue and to modifications of the mechanical properties of still-functional units. The lungs were chara cterized structurally by an increase of L(mw) and ($) over bar d. In a ddition, in three lungs, an increase of L(ma) and a decrease of n/cm(2 ) were observed. Functionally, these lungs demonstrated a pattern comp atible with a mixture of fibrosis and emphysema.