Pulmonary function impairment in pneumoconiotic patients with progressive massive fibrosis

Progressive massive fibrosis (PMF) is the severe form of coal workers' pneumoconiosis (CWP). Clinical observations have suggested that the components of PMF are inhomogenous. There may be a significant diversity in the magnitude of pulmonary impairment for miners with PMF. This study is intended to investigate the relationship between radiological categories of PMF and pulmonary impairment.

Eighty-six coal workers with radiological evidence of PMF were enrolled. They were subdivided into 3 categories, i.e., A, B, and C according to the International Labour Office (ILO) classification. Maximal expiratory flow-volume curves and diffusing capacity were measured in each subject.

Our data reveal that forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were abnormally low in all categories. However, FVC was only mildly reduced in category A, and then rapidly decreased with the progression of radiological category. The major pattern of impairment for miners with PMF was obstructive, but there was an increasing trend for restrictive impairment for higher radiological categories. A normal spirogram was still observed in 6-11% of subjects in category A and even B. For diffusing capacity (DLCO), there was also a progression of impairment with transition from category A to categories B and C. Smoking miners had even lower FEV1/FVC and DLCO than did their non-smoking counterparts.

Pulmonary impairment increased with increasing radiological category even in PMF. Assessment of lung function should be individualized and carried out with a combination of tests, i.e., spirometry and DLCO measurement. The loss of lung function cannot be accounted for by different smoking habits.