Evaluation of breathlessness in asbestos workers. Results of exercise testing.

We studied 120 asbestos-exposed workers seeking compensation for asbestos-related ventilatory impairment who were referred to us for evaluation of their complaint of dyspnea. We reviewed history, chest radiographs, pulmonary function studies, and exercise tests. The workers were 59.9 +/- 9.5 (mean +/- SD) yr of age and their first asbestos exposure had been 34.4 +/- 10 yr prior to the study; 63% were smokers, 19% were ex-smokers, and 18% were nonsmokers. Chest radiographs were normal in 4%, showed only pleural disease in 35%, only parenchymal diseases in 5%, and pleuroparenchymal disease in 56%. Restrictive pulmonary function abnormalities were present in 25% of the workers, and obstructive abnormalities were present in 27%. Because the impairment of one of several organ systems (i.e., ventilatory, cardiac, pulmonary vascular, or peripheral circulatory) may limit exercise performance, we designed an exercise test score in an attempt to identify the system causing the limitation. No abnormal limitation was detectable in half (49.2%) of the subjects. Only 26% had a ventilatory limitation, which was much more frequent in smokers (32%) than in nonsmokers (9%) (p less than 0.05). Unexpectedly, rather more (37%) had a cardiac rather than a ventilatory limitation. We conclude that the complaint of dyspnea in these asbestos-exposed workers was usually not caused by a ventilatory dysfunction.