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KMID : 0381319710100010013
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Korean Journal of Occupational Health
1971 Volume.10 No. 1 p.13 ~ p.27
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Impairment of Pulmonary Function in Coal Workers Pneumoconiosis
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Abstract
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In diagnosis of pneumoconiosis resulting from the inhalation of silica or coal dust, x-ray findings as well as occupational history of exposure to dusty environment are absolutely essential. Although pulmonary function does not alter in ther early stage of pneumoconiosis, it is known that ventilatory capacity, airway resistance and gas exchange become impaired as the disease progresses.
This study is designed to reevaluate the values of assessment of disability already set for the compensation. The following results are obtained by analyzing the data of pulmonary function obtained from 520 pneumoconiotics.
(1) Impairment of pulmonary function is not directly dependent on the duration of working experience, but rather dependent on the dust concentration in working places to which workers are exposed.
(2) Vital capacity (F.V.C.) and timed vital capacity(F.E.V._(1.0)) diminish remarkably as the disability advances. Vital capacity ratio,(F.E.V._(1.0))/F.V.C.×100, shows decrease only in moderate and severe disability cases.
(3) Maximum breathing capacity diminishes as the disability advances though there is no difference of mean values between slight and moderate disability cases. This is probably due to the fact that age and physiques are out of consideration.
(4) Both ventilatory reserve and ventilatory index decrease as the disability advances. Rate of the decrease is much greater in the latter than in the former and shows marked decrease in the advanced disability cases.
(5) Exercise index shows greater increase than other values or indices as the disability advances and especially in the advanced disability cases.
(6) X-ray findings do not necessarily coincide with the impairment of pulmonary function. In majority of the pneumoconiotics with category Ⅰ. their pulmonary functions are not altered and in cases with category Ⅱ and Ⅲ, slight or moderate impairment can be seen.
(7) Many of those cases who complain marked dyspnea clinically tend to show the increment of the cases of functional impairment of the lungs. But, a quite number of cases still remain with their pulmonary fuctions unaltered unlcss they complain severe dyspnea.
(8) Impairment of pulmonary function is not affected by the complication of pulmonary tuberculosis. It is mainly affected by the pathological changes of pneumoconiosis itself and complications other than tuberculosis such as pulmonary emphysema, pleural thickening, pneumothorax, etc.
(9) Type of ventilation due to pneumoconiosis is either normal or obstructive, it is presumed that marked contraction of pulmonary parenchyma due to fibrosis is rare, and pulmonary damage is caused mainly by tuberculosis or other complications.
(10) Airway conductance in the pneumoconiotics diminishes markedly than in healthy subjects. But, no difference is found in airway conductance by category of the disease, degree of impairment of pulmonary function, and ventilatory types. As the airway conductance is dependent on total lung volume, specific conductance is more useful in the determination of the causal factor of impairment of pulmonary function.
(11) At present only the category Ⅰ pneumoconiosis is covered by workman´s compensation. Progression of the pneumoconiosis as well as impairment of pulmonary function due to category of the disease is supposed rather dependent on dust concentration to which the workers are exposed than on the duration of exposure. Therefore, whatever the category of the disease may be, it is desirable that pneumoconiosis cases should be compensated if their occupational history in the past disclose that they are exposed to dusty work places at which the dust concentrations exceed the threshold limit values.
(12) Though F.V.C. and F.E.V._(1.0) are of value in the assessment of impairment of pulmonary function, it is advised to keep in mind that each value should be expressed in ratios to the expected values in reference to age and body size.
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