Silicosis (Fibrotic Lung Disease)
What is this Condition?
Silicosis is a progressive disease characterized by nodular lesions, which frequently progress to fibrosis. It's the most common form of fibrotic lung disease.
Silicosis can be classified according to the severity of pulmonary disease and the speed of its onset and progression, it usually occurs as a simple illness that has no symptoms. Acute silicosis develops after 1 to 3 years in people who are exposed to high concentrations of silica (such as sand blasters and tunnel workers). Accelerated silicosis appears after an average of 10 years of exposure to lower concentrations of free silica. Chronic silicosis develops after 20 or more years of exposure to lower concentrations of free silica.
The prognosis is good, unless the disease progresses into the complicated fibrotic form, which causes respiratory insufficiency and cor pulmonale and is associated with pulmonary tuberculosis.
What Causes it?
Silicosis is caused by the inhalation and pulmonary deposition of crystalline silica dust, mostly from quartz. The danger to the worker depends on the concentration of dust in the atmosphere, the percentage of free silica particles in the dust, and the duration of exposure.
Industrial sources of silica in its pure form include the manufacture of ceramics (flint) and building materials (sandstone). It occurs in mixed form in the production of construction materials (cement); it's found in powder form (silica flour) in paints, porcelain, scouring soaps, and wood fillers, and in the mining of gold, coal, lead, zinc, and iron. Foundry workers, boiler scalers, and stonecutters are all exposed to silica dust and, therefore, are at high risk for developing silicosis.
What are its Symptoms?
Silicosis initially may cause no symptoms or it may produce shortness of breath on exertion, often attributed to being "out of shape" or "slowing down." If the disease progresses to the chronic and complicated stage, shortness of breath on exertion worsens, and other symptoms usually include rapid breathing and an insidious dry cough, which is most pronounced in the morning, appear.
Progression to the advanced stage causes shortness of breath on minimal exertion, worsening cough, and pulmonary hypertension. People with silicosis have a high incidence of tuberculosis.
Central nervous system changes, such as confusion, lack of energy, and a decrease in the rate and depth of breathing as the partial pressure of carbon dioxide increases, also occur in advanced silicosis. Other clinical features include malaise, disturbed sleep, and hoarseness.
How is it Diagnosed?
The person's history reveals occupational exposure to silica dust. A physical exam is normal in simple silicosis; in chronic silicosis with conglomerate lesions, it may reveal signs of lung damage. Diagnostic tests include pulmonary function studies, chest X-rays, and arterial blood gas studies.
How is it Treated?
The goal of treatment is to relieve respiratory symptoms, to manage oxygen deficiency and cor pulmonale, and to prevent respiratory tract irritation and infections .Treatment also includes careful observation for the development of tuberculosis. Respiratory symptoms may be relieved through daily use of bronchodilating sprays and increased fluid intake (at least 3 quarts [liters] daily). Steam inhalation and chest physical therapy techniques, such as controlled coughing and segmental bronchial drainage, with chest percussion and vibration, help clear secretions. In severe cases, it may be necessary to administer oxygen by cannula or mask (1 to 2 quarts [liters] per minute) for the person with chronic hypoxia (low level of oxygen in the tissues), or by mechanical ventilator. Respiratory infections require antibiotics.