The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Environmental Medicine: Integrating a Missing Element into Medical Education
Radiographic Techniques
❑ Radiographic results should not be used preferentially in diagnosing asbestosis.
The chest X ray is the basic tool for assessing asbestos-associated parenchymal and pleural disease. Radiographic findings may include interstitial fibrosis in the lower lung fields and thickening of both the parietal and visceral lung pleura. Parietal pleural thickening generally appears as a tabulated prominence of the pleura adjacent to the thoracic margin. Visceral pleural thickening is generally more diffuse and appears as interlobar fissure thickening on lateral films. A system has been proposed by the International Labor Organization for radiographic rating of the changes in pneumoconioses. The diagnosis of asbestosis should be made in the context of the overall clinical presentation and should include, but not emphasize, X-ray findings. The association of pleural thickening and calcification enhances diagnostic accuracy; however, open lung biopsy is the only definitive diagnostic test for asbestosis.
The radiologic appearance of asbestos-induced lung cancer does not differ from that of other cancers. Asbestos-related malignancies predominantly involve the lower portion of the lungs, but they are not restricted to this location.
Computerized Tomography
❑ CT scanning is too expensive for use as a screening tool, but may be helpful in certain cases.
Computerized tomography (CT) scanning is a particularly sensitive means of differentiating asbestos-related pleural plaques from soft-tissue densities. The technique is being used to diagnose other asbestos-associated abnormalities as well. Because it is considerably more expensive than standard X rays, CT scanning should not be considered a screening tool.
Pulmonary Function Testing
❑ Small airway disease and restrictive defects are typical in nonsmoking patients with asbestosis; combined obstructive/ restrictive pattern is more typical in smokers.
Nonsmoking patients with asbestosis typically have spirometric changes indicative of small airway disease and restrictive defects; smokers with asbestosis may have a combined obstructive/restrictive pattern. Small airway disease is a common early finding and is reflected in a 25% to 74% reduction of forced expiratory flow rates. This change may reflect early fibrosis in the peribronchiolar areas or inflammatory changes. Restrictive defects are observed as a reduction in forced vital capacity. Because such reduction may also occur in obstructive airway disease, an apparent combined pattern of restrictive and obstructive disease should be followed up with further pulmonary studies including carbon monoxide diffusion capacity and static
Items in cart [0]
