Development of radiological and functional changes in silicosis during the long term follow-up

Summary

The report follows up the development of radiologic changes and functional disorders in 200 patients with silicosis who were repeatedly examined over a period of time. The patients were divided according to the X-ray findings, when first detected, into groups of simple silicosis, complicated silicosis, and simple silicosis passing into the complicated stage during the study. Each group was divided into 3 time periods of follow-up: 3 to 5 yrs, 6 to 10 yrs, and 11 to 17 yrs between the first and the last examinations. The results disclosed the following conclusions:

• 1. Changes of the radiologic picture evaluated according to the International Classification of Pneumoconiosis ILO 1971 proceeded in the course of time into more serious forms with respect to size and profusion of nodules. With complicated silicosis, possibly with the transient form, the auxiliary symbols increased with time, particularly “ax”, “pl”, “em”, “es”, “tbu”, and “tba”. The classification proved satisfactory for expressing shifts of X-ray changes; it did not suffice alone, however, for answering the question when a dust finding reaches the stage at which it is to be declared an occupational disease. This would require more criteria, chiefly tomography of the lungs and assessment of the dynamics of development in radiologic changes.

• 2. The trend of the ventilatory-function decrease differed only slightly in a mutual comparison of the groups. This means that in the intermediate and long time periods the decrease in ventilatory function is similar because the patients with severe functional disorders do not live long enough for long-term studies. This was proved by an analysis of the mortality rate in the groups.

• 3. We ascertained more significant differences in the ventilatory function within the individual groups in patients with signs of chronic bronchitis when compared with patients without bronchitis. The important influence especially of the obstructive form associated with complicated silicosis was evident here.

• 4. Part of the group was also studied from the aspect of blood gases and acid-base status over periods of 3 to 5 and 6 to 10 yrs. With both forms of silicosis the values of the first and last examinations differed only insignificantly. Pronounced changes of the respiratory function cannot be expected when the organism is able to compensate the disorder of ventilation. The finding of global respiratory insufficiency with rapid progress of silicosis always indicated a limited life expectancy.