Airways Obstruction From Asbestos Exposure: Data
Another possibility, that volume has been replaced by fibrosis in normal-sized lungs, would increase the postmortem weight of lungs. Weight is not increased in asbestosis nor are alveoli filled by nonradiodense material as in alveolar lipoproteinosis.
Alternately there would be “apparent restrictive impairment” if obstruction continued through advancement of asbestosis causing air trapping and progressive reduction of FVC within a normal TLC. The ideal demonstration of the time course of functional impairment of asbestosis would be by periodic pulmonary function measurements during a life-long study of an asbestos-exposed population accompanied by morphometric studies of the lungs of decedents. Lacking the luxuries of 20 years and funding for follow-up from these baselines, another approach is to assume that the profusion of irregular opacities approximates the structural abnormality and construct the time course using cross-sectional data.
We compared measurements of pulmonary function in a large asbestos-exposed population in which the radiographic (anatomic) lesions were graded for severity using the ILO profusion of categories for irregular opacities. The analytic strategy compared the functional effects of asbestos exposure and asbestosis using age-matched comparisons, separately in men who never smoked and in current and ex-cigarette smokers, compared with the three smoking groups unexposed to asbestos there contraceptive pills. Asbestosis was defined as the presence of any ILO profusion of irregular opacities of 1/0 or greater on standard chest radiographs. We studied 8,720 men who had been exposed initially to asbestos-containing insulating materials at least 15 years earlier. The structure-function relationships were compared in groups, the residuals were calculated, and pulmonary function measurements as independent variables were modeled by regression against ILO profusion categories and duration of asbestos exposure. Profusion categories were converted to positive integers (1 for 0/0 to 10 for 3/3).