Asbestosis

Asbestosis - lung diseases associated with exposure to asbestos, are caused by inhalation of asbestos fibers. Diseases include asbestosis; lung cancer; formation of benign lesions of the pleura and its thickening; benign pleural effusions and malignant pleural mesothelioma. Asbestosis and mesothelioma lead to progressive dyspnea.

The diagnosis is based on anamnesis and chest radiographs or CT and, in case of malignant growth, tissue biopsy. The treatment of asbestosis is effective, except for malignant tumors that may require surgical and / or chemotherapeutic treatment.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]

What causes asbestosis?

Asbestos is a naturally occurring silicate whose heat-stable and structural properties have made it useful for construction and shipbuilding, it is used in automotive brakes and some textile industries. Chrysotile (snake fiber), chrcidotyl and amosite (amphibole, or straight fibers) are the 3 main types of asbestos fibers that are the cause of the disease. Asbestos can affect the lungs and / or the pleura.

Asbestosis - a form of interstitial pulmonary fibrosis, occurs much more often than malignant diseases. Shipbuilders, builders and workers of the textile industry, workers engaged in the restructuring and repair of living quarters, workers and miners exposed to asbestos fibers are among the numerous categories of persons at risk of disease. Secondary lesions can occur among family members of sick workers and among those who live close to mines. Pathophysiology is similar to that of other pneumoconiosis - alveolar macrophages, trying to absorb inhaled fibers, secrete cytokines and growth factors that stimulate inflammation, collagen deposition and ultimately fibrosis, except that the fibers of asbestos itself can also be directly toxic to tissue lung. The risk of the disease is usually associated with the duration and intensity of the contact and type, length and thickness of the inhaled fibers.

Symptoms of asbestosis

Asbestosis initially occurs asymptomatically, that is, when symptoms of asbestosis are absent, but can cause progressive dyspnoea, unproductive cough and malaise; the disease progresses in more than 10% of patients after discontinuation of contact. Prolonged leaking asbestosis can cause thickening of the terminal phalanges of the fingers, dry basilar rales, and, in severe cases, symptoms and manifestations of right ventricular failure (pulmonary heart).

Pleural lesions - a sign of lesions with asbestos - include the formation of pleural overlays, calcification, thickening, adhesions, effusion and mesothelioma. Pleural injuries are accompanied by effusion and malignant development, but a small number of symptoms. All pleural changes are diagnosed by chest X-ray or HRCT, although CT of the chest is more sensitive than X-rays to detect pleural lesions. Treatment is rarely required, except for cases of malignant mesothelioma.

The discrete overlap that occurs in 60% of workers exposed to asbestos typically affects the parietal pleura from both sides at the level between the fifth and ninth ribs adjacent to the diaphragm. Calcification of spots is common and can lead to an erroneous diagnosis of severe lung damage if radiologically superimposed on the pulmonary fields. HRCT can distinguish between pleural and parenchymal lesions in such cases.

Diffuse thickening occurs both in the visceral as well as in the parietal pleura. This can be the spread of pulmonary fibrosis from the parenchyma to the pleura or a nonspecific response to pleural effusion. With or without calcification, pleural thickening can cause restrictive disorders. Rounded atelectasis is a manifestation of pleural thickening, in which intussusception of the pleura into the parenchyma can draw the tissue of the lung into the "trap", causing atelectasis. On thoracic and CT scans, it is typically defined as cicatricial mass with an uneven contour, often at lower lying areas of the lung, and can be taken radiographically for a pulmonary malignant neoplasm.

Pleural effusion also occurs, but less frequently than other pleural lesions that it accompanies. Exudation is an exudate, often hemorrhagic, and usually disappears spontaneously.

Diagnosis of asbestosis

The diagnosis of "asbestosis" is based on an anamnesis of contact with asbestos and CT or chest X-ray. Chest X-ray reveals linear reticular or focal infiltrates that reflect fibrosis, usually in the peripheral parts of the lower lobes, often accompanied by pleural lesions. "Honeycomb" reflects the great neglect of the disease, which may involve middle pulmonary fields. As with silicosis, severity is determined by the scale of the International Labor Organization, based on the size, shape, location and severity of infiltrates. Unlike silicosis, asbestosis causes reticular changes mainly in the lower lobes. Adenopathy of the roots and mediastinum is atypical and suggests a different diagnosis. Chest X-ray is not informative; CT of a thorax with high resolution (KTVR) is informative when asbestosis is suspected. HRCT also excels chest radiography in identifying pleural lesions. Lung function tests that can detect decreased lung volumes are non-diagnostic, but help characterize changes in lung function for a long time after the diagnosis is established. Bronchoalveolar lavage or lung biopsy is prescribed only when atraumatic methods fail to establish a definitive diagnosis; the detection of asbestos fibers indicates asbestosis in people with pulmonary fibrosis, although such fibers can sometimes be found in the lungs that have been exposed to people without a disease.

[12], [13], [14], [15], [16], [17]

Treatment of asbestosis

There is no specific treatment for asbestosis. Early detection of hypoxemia and right ventricular failure leads to the use of additional 02 and the treatment of heart failure. Pulmonary rehabilitation can be useful for patients with worsening of the disease. Preventive measures include the removal of contact with the substance, the reduction of asbestos in non-working premises, cessation of smoking and vaccination against pneumococcus and influenza. Cessation of smoking is particularly important in terms of the multifactorial risk of lung cancer in those who are exposed to both asbestos and tobacco smoke.

What is the prognosis of asbestosis?

Asbestosis has a different prognosis; many patients safely live without symptoms or with mild symptoms, while some suffer from progressive dyspnea, and few patients develop respiratory failure, right ventricular failure and malignant growth.

Lung cancer (non-small cell) develops in patients with asbestosis 8-10 times more often than patients without asbestosis, and is particularly common in workers exposed to amphibole fibers, although all forms of inhaled asbestos are associated with an increased risk of cancer. Asbestos and smoking have a synergistic effect on the risk of lung cancer.