The role of fibrosis in the small airways in centrilobular emphysema.

Small non-respiratory bronchi of lungs of patients suffering from slight and severe centrilobular emphysema of city dwellers and from focal dust emphysema, has been studied, by means of serial sections assessing the importance of the connective tissue proliferation in relation to the cross-sectional morphology of the bronchus, its diameter and longitudinal profile. Camera lucida drawings of parietal muscle and reconstructions of the bronchial wall and lumen were done. A positive relationship between the amount of the connective tissue proliferation, the severity of emphysema and the changes in the parameters indicated was found. The repercussion of fibrosis in the small airways disease of centrilobular emphysema, can be summarized as follows: the production of areas of localized stenosis, the contribution to the development of bronchiolar deformities, the obliteration of some airways and the alteration of bronchial muscle. It can be concluded, therefore, that the fibrosis, as second main cause of small airways obstruction, has a more wide repercussion on the bronchiolar structure than that of alveolar loss, and that it can probably affects not only the "static" characteristics of the bronchial wall, but also their "dynamic" behaviour by means of disorganization of the muscle.