Asbestosis

ASBESTOSIS

Asbestosis is a disease characterized by diffuse pulmonary fibro-sis from the inhalation of asbestos dust. Current laws restrict the use of asbestos, but many industries used it in the past. Therefore, exposure occurred, and may still occur, in numerous occupations, including asbestos mining and manufacturing, shipbuilding, de-molition of structures containing asbestos, and roofing. Materi-als such as shingles, cement, vinyl asbestos tile, fireproof paint and clothing, brake linings, and filters all contained asbestos at one time, and many of these materials are still in existence. Additional diseases related to asbestos exposure include lung cancer, mesothe-lioma, and asbestos pleural effusion.

Pathophysiology

Inhaled asbestos fibers enter the alveoli, where they are surrounded by fibrous tissue. The fibrous tissue eventually obliterates the alve-oli. Fibrous changes also affect the pleura, which thickens and de-velops plaque. The result of these physiologic changes is a restrictive lung disease, with a decrease in lung volume, diminished exchange of oxygen and carbon dioxide, and hypoxemia.

Clinical Manifestations

The onset of the disease is insidious, and the patient has progres-sive dyspnea, persistent, dry cough, mild to moderate chest pain, anorexia, weight loss, and malaise. Early physical findings include bibasilar fine, end-inspiratory crackles and in more advanced cases clubbing of the fingers. Cor pulmonale and respiratory failure occur as the disease progresses. A high proportion of workers who have been exposed to asbestos dust die of lung cancer, especially those who smoke or have a history of smoking. Malignant mesothe-liomas may also occur. These are rare cancers of the pleura or peri-toneum that are strongly associated with asbestos exposure.

Medical Management

There is no effective treatment for asbestosis as the lung damage is permanent and often progressive. Management is directed at controlling infection and treating the lung disease. When oxygen– carbon dioxide exchange becomes severely impaired, continuous oxygen therapy may help improve activity tolerance. The patient must be instructed to avoid additional exposure to asbestos and to stop smoking. A significant contributing cause to mortality in this population is the high incidence of lung carcinoma.