According to the histological picture of coal workers’ pneumoconiosis (CWP), with dust foci around the vessels and the bronchi and sometimes intraalveolarly, with fibrosis in all these locations, and with nodulations and bigger fibrotic lesions, we would expect all parts of the lung function to be disturbed. We would expect that breathing mechanics, pulmonary circulation, gas exchange, and especially diffusion capacity would be influenced, depending on the stage of CWP. Further, we would expect to arrive at a rough idea of the stage of CWP by x-ray examination of the coal miners. Surprisingly enough, the expected correlation between histology and lung function does not exist. It is not uncommon to see coal miners with severe CWP on x-ray films (FIGURE 1) but with lung function values in the normal range (TABLE 1). This conclusion is also true from the statistical point of view. FIGURE 2 shows the frequency of the different values from static compliance of the lung on 90 coal workers with CWP, stage I (according to the Johannesburg classification) and on 26 with stage 111. In the same figure is shown the range found in normal people. Only a few of the coal miners with CWP were found to be outside of the “normal range.” About 3% of coal workers with CWP clearly show decreased values of static compliance and also show corresponding clinical signs of dyspnea, especially under physical stress. Sometimes, all the other values, such as pulmonary circulation or gas exchange, are in the normal range or show only some slight differences from the normal range. Thus, 97% show normal or slightly increased values of static compliance. The reason may be that some areas of these lungs (the fibrotic regions) have increased static compliance and other areas (perifocal emphysematous regions) have decreased compliance. The result is normal values in the mean. Without doubt, these patients have no difficulties from lung function, so long as other parts of function are not influenced. In the cases without disturbances of ventilation, only seldom is the resistance in pulmonary circulation increased. FIGURE 3 shows the results of the right heart catheterization in 35 coal workers with severe CWP but without disturbance of ventilation. 20% show slightly increased values of the pressure in the arteria pultnonalis at rest, and about 30% show slightly increased values at work. But it is important to know that the x-ray variation was enormous, the mean values were only a little above the normal range, and most of the individual values of the individual cases were in the normal range. Only one of those cases showed a more pronounced increased pressure; with 45 mm Hg at rest and 49 mm Hg at 30 watts. Thus, we must also conclude that only in rare cases of CWP without influenced ventilation (about 3% ) was pnlmcnary circulation disturbed in such a way that general health was significantly influenced.
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