Asbestosis: Causes, Symptoms, Treatment, Diagnosis

What is Asbestosis?

Asbestosis is the pulmonary parenchymal fibrosis resulting from exposure to asbestos. This condition usually develops nearly 20 years after first exposure to a large amount of exposure of asbestos. Asbestosis is rare in the absence of asbestos related pleural changes.

What are Causes of Asbestosis?

Asbestos fibers get deposited at the branch points of respiratory bronchioles.
They are phagocytosed by alveolar and interstitial macrophages that become activated.
These release cytokines and other inflammatory mediators that injure lung parenchyma and cause alveolitis.
There is also release of super oxide anions and hydroxyl radicals which results in damage to the basement membrane and fibrosis sets in.

What are the Symptoms of Asbestosis?

Progressive shortness of breath on exertion and non-productive cough.
Examination reveals persistent late inspiratory crackles, localized initially in lower zone, but later becomes wide spread.
As pulmonary fibrosis becomes more severe there will be clubbing of digits, central cyanosis and signs of pulmonary hypertension and cor-pulmonale.

Investigations of asbestosis

Radiographic findings are characterized by scattered, small, irregular or linear opacities in lower and mid lung zone and are usually associated with pleural thickening or plates.
Pulmonary function tests reveal presence of restrictive ventilatory defect and impaired gas transfer.
Evidence of airflow obstruction is also commonly present, mainly due to smoking, though asbestosis can alone cause small airway narrowing due to development of fibrosis around the circumference of small airways.
Sputum may show asbestos bodies.
BAL (bronchoscopic aspiration lavage) shows presence of large number of inflammatory cells and increased amount of fibronectin.
CT-scan chest is more sensitive to detect the pleural and pulmonary disease. The finding include- sub-pleural urvilinear opacities, parencymal bands, increased inter-lobular septa, thickening of bronchioles and pleura and honey combing of the pulmonary parenchyma.

Treatment of Asbestosis

Stop of smoking.
Further exposure to asbestos to be avoided.
In rapidly progressive disease steroids may be given for trail.