Silicosis And Asbestosis
Silicosis and asbestosis are chronic lung diseases. The biggest problem is their continuous progress, their complications and the fact that they are badly treatable.
In both cases, the causative factor is an inhaled substance from the external environment – silica in silicosis and asbestos in asbestosis. Some occupations are more risky, for example miners and industrial workers.
Both compounds are inhaled and reach the lung alveoli. Local immune defense cells (macrophages) try to destroy the particles and engulf them. Unfortunately, the macrophages are unable to destroy both silica and asbestos and what is worse; they are damaged and succumb to necrosis. The necrosis of multiple immune cells causes local inflammation. The harmful particles are released, “digested” by other macrophages and the vicious circle continues. As the process progresses, the lung tissue is permanently damaged by immune process and aggressive substances released from the decaying macrophages. The inflammation causes occurrence of lung fibrosis that interferes with the exchange of respiratory gases between the lungs and blood.
The manifestations of the disease appear slowly and worsen over years. Initially, the person has no symptoms and later, dry cough and progressive shortness of breath occur. The tissues are inadequately supplied with oxygen and the person gets short of breath during physical exercise and later even during everyday tasks. The pleura (membrane covering the chest cavity) may get irritated causing pleurisy with chest pain that worsens during inspiration.
The lung fibrosis may lead to heart disease. How is that possible? When parts of the lungs stop exchange the breathing gases, local blood vessels reflexively narrow. This increases local resistance of the lung circulatory system and overloads the heart that must pump harder to overcome the resistance. There is an increased risk of a right-sided heart failure. In addition, long-term contact with asbestos significantly increases the risk of malignant mesothelioma (tumor of the pleura).
When suspected silicosis or asbestosis, it is necessary to know the patient’s history and find out information about close contact with silica or asbestos. The changes of lung tissue may be visualized by a chest X-ray or even better by a computed tomography. The function of the damaged lung tissue can be evaluated by functional examination of the lungs (such as the spirometry). The function of the right heart ventricle can be examined by echocardiography.
The best prevention is wearing adequate protective equipment (such as breathing masks, filters, etc.) when working in environment with silica or asbestos presence.
We can not cure the disease, but we can at least treat the symptoms. Usually, we use medications that enhance the airways, improve breathing and dampen the cough. In advanced stages of the disease, oxygen is the “drug” of choice and the patients may be indicated for the home oxygen therapy. Immunosuppressive drugs as the corticosteroids may be used to dampen the inflammation, but their long- term use has many unpleasant side-effects. The ultimate therapy is the lung transplant, but this major surgical procedure is performed in only minimum number of patients.