industrial lung disease Flashcards
definition
Occupational lung disease are a result of exposure to dusts, gases, fumes and vapours at work. There are many lung diseases that are associated with industrial exposure to such factors. Included in this classification of disease are:
what are the 3 main types of industrial lung disease
coal workers pneumoconiosis
silicosis
asbestosis
pneumoconiosis- define
Pneumoconiosis is a term used to signify the accumulation of dust in the lungs and the reaction of the tissue to its presence.
It is now generally restricted to the effects of coal dust and is also known as coal worker’s pneumoconiosis.
types:
simple
progressive massive fibrosis [PMF]
CAPLAN’S SYNDROME
define simple pneumoconiosis
Simple pneumoconiosis is caused by the accumulation of relatively small (up to 5mm in diameter) aggregations of coal particles.
These particles are roughly uniformly distributed and are seen on the chest radiograph as delicate micronodular mottling, appearance determining grading.
DEFINE PMF
In PMF round, fibrotic masses, which may be several centimetres in diameter, are present in the lungs. These are usually present in the upper lobes of the lung and may have necrotic central cavities.
It is as yet unclear why some individuals develop PMF whilst others with similar exposure to coal dust do not.
define caplan’s syndrome
Caplan’s syndrome is the association of rheumatoid lung nodules and pneumoconiosis. Originally described in coal miners with progressive massive fibrosis, it may also occur in asbestosis, silicosis and other pneumoconioses.
Chest radiology shows multiple, round, well defined nodules, usually 0.5 - 2.0 cm in diameter, which may cavitate and resemble tuberculosis.
Lung function tests may reveal a mixed restrictive and obstructive ventilatory defect with a loss of lung volume. There may also be irreversible airflow limitation and a reduced gas transfer factor.
Rheumatoid factor, antinuclear antibodies, and non-organ specific antibodies may be present in the serum. The nodules may pre-date the appearance of rheumatoid arthritis by several years, but it is possible that articular manifestations of rheumatoid arthritis may never develop.
Treatment is with steroids (after tuberculosis has been excluded).
pneumoconiosis s/s and what would cxr show
- progressive dyspnoea
- chronic bronchitis
PMF s/s:
- he patient may cough up large amounts of black material.
- Chest radiology will reveal large, round opacities in the lung fields.
- Lung function tests may reveal a restrictive ventilatory defect:
- both VC and FEV1 are decreased in proportion
- FEV1/FVC (forced expiratory ratio) is normal or even higher than normal
- there is a variable reduction in transfer factor
cxr: upper zone fibrotic mass
silicosis- define, s/s
Silicosis is a fibrosing lung disease caused by the inhalation of fine particles of crystalline silicon dioxide (silica).
It is a risk factor for developing TB (silica is toxic to macrophages).
Occupations at risk of silicosis
- mining
- slate works
- foundries
- potteries
Features
- fibrosing lung disease
- ‘egg-shell’ calcification of the hilar lymph nodes
Asbestososis- define, s.s, ix
Asbestosis is a pneumoconiosis caused by inhalation of asbestos fibres, classically causing a chronic, diffuse, interstitial fibrosis of the lung. Crocidolite - blue asbestos - is the most important type of asbestos in the aetiology of asbestosis and particularly, pleural and peritoneal mesothelioma.
Asbestos exposure increases the risk of bronchogenic carcinoma 5-fold. In exposed cigarette smokers, the risk is increased 55-fold. An asbestos-related increase is also observed in the incidence of gastric, colonic and renal adenocarcinoma, and of gastrointestinal lymphomas.
Under the UK Social Security Act of 1975 various conditions caused by asbestos exposure are eligible for industrial compensation, including bilateral diffuse pleural thickening, asbestosis, mesothelioma and asbestos related carcinoma of the bronchus.
Clinical features:
- progressive dyspnoea
- clubbing
- bilateral end-inspiratory crackles
Investigations:
CXR - diffuse bilateral shadowing, honeycomb lung. There may be pleural plaques which are an indicator of previous exposure to asbestos. However, pleural plaques do not indicate lung disease or any increased risk over similarly exposed subjects of developing a tumour.
Lung function tests - severe restrictive ventilatory defect; reduced gas transfer.
Lung fibrosis not detectable on CXR may be revealed on CT scan.
asbestos + the lung- FACTS
Asbestos and the lung
Asbestos can cause a variety of lung disease from benign pleural plaques to mesothelioma.
Pleural plaques
Pleural plaques are benign and do not undergo malignant change. They are the most common form of asbestos related lung disease and generally occur after a latent period of 20-40 years.
Pleural thickening
Asbestos exposure may cause diffuse pleural thickening in a similar pattern to that seen following an empyema or haemothorax. The underlying pathophysiology is not fully understood.
Asbestosis
The severity of asbestosis is related to the length of exposure. This is in contrast to mesothelioma where even very limited exposure can cause disease. The latent period is typically 15-30 years. Asbestosis typically causes lower lobe fibrosis. As with other forms of lung fibrosis the most common symptoms are shortness-of-breath and reduced exercise tolerance.
Mesothelioma
Mesothelioma is a malignant disease of the pleura. Crocidolite (blue) asbestos is the most dangerous form.
Possible features
- progressive shortness-of-breath
- chest pain
- pleural effusion
Patients are usually offered palliative chemotherapy and there is also a limited role for surgery and radiotherapy. Unfortunately the prognosis is very poor, with a median survival from diagnosis of 8-14 months.
Lung cancer
Asbestos exposure is a risk factor for lung cancer and also has a synergistic effect with cigarette smoke.
