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16 Cards in this Set
- Front
- Back
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Definition |
Diffuse interstitial fibrosis of the lung as a consequence of exposure to asbestos fibres
Abnormalities include: plaques, pleural thickening, pleural effusions or rounded atelectasis |
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Epidemiology |
Exposure common among workers in the shipyard, construction, and building maintenance industries
Typically seen in individuals who began working with asbestos prior to the 1980s and are now usually >50 years of age |
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Aetiology |
Inhalation of asbestos fibres. Asbestos is a fibrous silicate, which exists as a naturally occurring mineral. Chrysotile is the primary asbestos mined
Airborne asbestos particles <10 microns can be inhaled |
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Pathophysiology |
Fibres deposit at alveolar duct bifurcations and cause an alveolar macrophage alveolitis.
Release cytokines, such as tumour necrosis factor and interleukin-1beta and oxidant species, which initiate a process of fibrosis
Starts in lower lobes and may progress to extensive fibrosis and honeycombing
Clearance of asbestos fibres is through lymphatic drainage and the pleural cavities |
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Signs, symptoms and risk factors |
Symptoms: dyspnoea, cough
Signs: crackles and maybe clubbing
Risk factors: occupational exposure and duration of occupational exposure
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Investigations |
CXR: lower zone fibrosis and pleural thickening Spirometry: restrictive HRCT: same as CXR but clearer
Lung biopsy: asbestos mineral fibres |
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DDx |
Idiopathic pulmonary fibrosis, Connective tissue disease, auto-immune (sarcoidosis) and silicosis |
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Criteria |
1. Structural changes on CXR
2. Occupational exposure
3. Exclusion of alternatives |
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Treatment |
Smoking cessation Supportive care (antibiotics and steroids on standby + bronchodilator if it helps Pulmonary rehab and oxygen Lung transplant (end stage respiratory failure
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Managment |
Monitoring with CXR and PFTs. Risk of lung cancer and mesothelioma Smoking cessation |
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Prognosis |
Varies depending on level of exposure and progression of fibrosis |
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IPRATROPIUM BROMIDE |
Antimuscarinic bronchodilator - Cholinergic receptor angonist - Decreases cGMP > decreases calcium > smooth muscle relaxation |
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TIOTROPIUM BROMIDE |
Antimuscarinic bronchodilator. Decreases cGMP > decreases calcium > smooth muscle relaxation but longer acting. Acts on M3 receptors |
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METACLOPROMIDE |
Anti-emetic. Dopamine agonist. Inhibits gastric smooth muscle |
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OMEPRAZOLE |
PPI acts on H+ K+ ATPASE. Blocks final step of acid production |
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RAMIPRIL |
ACE inhibitor. Stops conversion of ATI to ATII. ATII increaes blood pressure via RAAS system by stimulating ADH, increases aldosterone and binds to smooth muscle by binding to smooth muscle |
