Asbestos is a form of pneumoconiosis that develops as a result of prolonged inhalation of asbestos–containing dust and is characterized by diffuse fibrosis of the lung tissue. The symptoms consists of general somatic disorders (malaise, fatigue, anorexia), signs of respiratory insufficiency (shortness of breath, cyanosis, deformation of the terminal phalanges of the fingers), symptoms of respiratory damage (cough with mucous sputum, pleural syndrome). For the diagnosis, X-rays, CT of the lung, spirometry, examination of sputum and bronchial flushing waters are used. In case of disease, supportive therapy is performed (respiratory gymnastics, physiotherapy, oxygen therapy).
ICD 10
J61 Pneumoconiosis caused by asbestos and other minerals
Meaning
Asbestos pneumoconiosis, or asbestosis, is diffuse interstitial pneumosclerosis caused by inhalation of asbestos particles. Along with talcosis, it refers to silicatoses – lung lesions caused by exposure to the lung tissue of silicic acid compounds. Disease is observed in persons engaged in the extraction and processing, as well as working with asbestos-containing materials. The greatest prevalence is registered in Canada, the country holding the world championship in asbestos reserves. The frequency of occurrence increases in proportion to the increase in the time of contact with this material and averages 25-65% of cases. The danger lies not only in the development of diffuse fibrosis of the lung tissue, but also in the formidable long–term consequences – an increased risk of the development of asbestos tuberculosis, pleural and peritoneal mesothelioma, lung and stomach adenocarcinoma.
Asbestos causes
The immediate cause of this form of pneumoconiosis is prolonged inhalation of asbestos fibers. At the same time, asbestos can develop both with a work experience of less than 3 years, and 15-20 years after the termination of professional contact with asbestos dust. Disease is a fine-fiber mineral represented by a hydrosilicate of magnesium, iron, calcium and sodium. Among the various varieties of pathology, serpentine asbestos (chrysotile and antigorite), as well as amphibole form (amosite, anthophyllite, crocidolite, tremolite) are of the greatest industrial importance – the latter are characterized by greater fibrogenicity and carcinogenicity.
By the nature of their professional activity, workers engaged in the asbestos mining and processing industry, construction, engineering, shipbuilding, and aviation industries are in close contact with asbestos. These individuals constitute an increased risk group for the development of disease. In addition, there are cases of the incidence with relatively short and non-intensive exposure to asbestos-containing dust, for example, among women washing their husbands’ work clothes, or painters and electricians working in a room where asbestos-containing materials are used. In addition to professional, household contact with asbestos is possible when using baby powder or asbestos textile products in residential buildings. It is known that smoking contributes to the occurrence of disease, its rapid progression and severe course.
Pathogenesis
The mechanism of development of pulmonary fibrosis in asbestos remains unclear. In pulmonology, it is customary to consider several versions of the occurrence of the disease: mechanical irritation of the lung tissue with asbestos needle fibers, damage to the alveoli by released silicon dioxide, cytotoxic effect of asbestos against macrophages, the development of immunopathological reactions, etc. There are pulmonary and pleural forms of asbestos. From the point of view of morphological changes in the lungs, asbestos in its development goes through two phases: desquamative alveolitis and bronchiolitis. Pneumofibrosis (pneumosclerosis) is interstitial in nature, localized mainly in the middle and lower lobes, while emphysema is determined in the upper parts. Asbestos is characterized by the presence of gross pleural adhesions, sometimes pleural effusion. In sputum, as well as in the pulmonary parenchyma, the presence of asbestos bodies is detected, however, this only confirms the fact of contact with asbestos dust, but is not the basis for establishing a diagnosis. In the pleural form, an isolated lesion of the pleura is noted with intact pulmonary parenchyma.
Asbestos symptoms
The severity of the symptoms depends on the duration of exposure to asbestos particles and their concentration in the air. It is believed that with 3-4 years of professional harmfulness, a mild form of asbestos develops, 8 years – moderate, 10 or more years – a severe form. Like the course of other pneumoconioses, the symptoms is characterized by chronic bronchitis and signs of emphysema of the lungs. All complaints and objective manifestations fit into three groups of symptoms: general somatic, signs of respiratory damage and respiratory failure. Nonspecific symptoms are malaise, fatigue, pallor, weakness, anorexia and weight loss. Warty growths often appear on the hands and feet – the so-called “asbestos warts”.
The involvement of the respiratory tract and pleura in the pathological process is indicated by the appearance of an unproductive cough or with scanty mucous sputum and severe chest pain. In severe cases, dyspnea is pronounced, cyanosis develops, thickening of the nail phalanges of the fingers is determined. It is possible to develop exudative pleurisy, which has a serous or hemorrhagic character.
Complications
The course of disease is often complicated by pneumonia, bronchiectatic disease, bronchial asthma, pulmonary heart, aggravating the prognosis of pneumoconiosis. Most often, the death of patients occurs from respiratory and cardiopulmonary insufficiency. The correlation of disease with rheumatoid arthritis was noted. Against the background of disease in patients, the risk of developing pulmonary tuberculosis (mainly its focal form), lung cancer, malignant mesothelioma of the peritoneum and pleura, cancer of the esophagus, stomach and colon increases several times.
Diagnostics
Examination of patients with suspected pneumoconiosis is carried out by a pulmonologist with the participation of a professional pathologist. In establishing the diagnosis of this disease, a crucial role belongs to the study of the professional route and the availability of data indicating the impact of asbestos dust. During auscultation, wet, small-bubbly (sometimes dry) wheezing, pleural friction noise are heard. Above the upper parts of the lungs, a box sound is percutorially determined. In blood tests, acceleration of ESR, hypergammaglobulinemia, RF, antinuclear antibodies, a decrease in the level of oxygen in arterial blood can be detected.
Radiological signs of pathology are linear-mesh deformation of the pulmonary pattern, basal fibrosis, pleural changes (plaques, splices, effusion), in the later stages – “cellular lung”. If the results of lung radiography are questionable, I resort to high-resolution CT of the lungs, which allows us to reliably consider subpleural linear, focal or irregular shadows.
The study of the function of external respiration in asbestos indicates the predominance of restrictive disorders over obstructive ones (reduction of the vent and respiratory volume, etc.). Due to the similarity of the clinical and radiological picture with other pneumoconioses, the differential diagnosis is carried out with anthracosis, hemosiderosis of the lungs, stannosis, talcosis, fibrosing alveolitis and other diseases. For this purpose, a microscopic analysis of sputum, a study of bronchial flushing waters, a biopsy of lung tissue, in which asbestos corpuscles and fibers are detected, is carried out.
Asbestos treatment
Since changes in the lungs with asbestos are irreversible, the disease is treated symptomatically. First of all, it is necessary to completely stop contact with asbestos, get rid of nicotine addiction, eliminate significant physical exertion. In order to avoid the addition of infections that aggravate respiratory failure, vaccination against influenza and pneumococcal infection is recommended. Supportive therapy is aimed at relieving symptoms; it includes postural drainage, chest massage, medicinal inhalations, breathing exercises, physiotherapy, and, if necessary, oxygen therapy. Medical treatment involves the use of inhaled bronchodilators, taking vitamins.
Prognosis and prevention
With the development of complications, the prognosis for working capacity and satisfactory quality of life is not encouraging: there is a high probability of disability, the development of severe concomitant diseases and the death of patients. Prevention of pathology infection consists of industrial and medical measures. The first of them presuppose the provision of the required sanitary and hygienic conditions and individual protection of workers, compliance with safety regulations. All workers who are in contact with asbestos or asbestos-containing materials must undergo periodic medical examinations according to the established schedule. Taking into account the increased risk of tuberculosis and malignant tumors against the background of disease, patients with an established diagnosis are recommended to be monitored by a phthisiologist and oncologist.