Heterogeneous ventilation and perfusion: a sensitive indicator of lung impairment in nonsmoking coal miners

Twenty life-long nonsmoking West Virginia coal-miners participated in a study to amplify the role of focal irregularities on regional ventilation (V.) and perfusion (Q.) and to develop an improved method for the early detection of coal-workers' pneumoconiosis. Their mean age was 59.3 yr and they averaged 35.2 years' exposure to coal dust. Conventional pulmonary function tests were supplemented by measurement of V.,Q. and lung volume (V), using radioactive Kr-81m, Tc-99m MAA and Xe-127, respectively, to determine regional abnormalities in lung function. A computer analysis of the regional distributions of V./V and Q./V were significantly reduced in the lower third, and increased in the upper two-thirds of the miners' lungs; V./Q. was reduced in the upper half. The miners' V./V and Q./V were more heterogeneous (p<0.001) than that of eleven age-matched controls, with mean ventilation HI values of 0.190±0.027 and 0.133±0.011, respectively, and mean perfusion HI values of 0.206±0.022 and 0.164±0.041, respectively. P(A-a)O2 correlated positively (r=0.72;p<0.001) with ventilation HI. Gas exchange was the most significant functional measurement, being abnormal in 19/20 subjects. In contrast, conventional spirometric measurements were within the predicted normal limits in all but four miners. (author)