Restrictive Lung Disease Flashcards
Describe the nature of restrictive lung disease and compare it with obstructive diseases?
Restrictive lung diseases is where your FVC is reduced as you cannot expand your lungs properly. In restrictive problems your FEV1 should be normal
In obstructive lung disease you should have a normal lung capacity however you cannot breath in and out properly due to obstruction therefore classically would have a reduced FEV1.
What is interstitial lung disease?
It is a category of lung diseases which affect the interstitium (essentially the connective tissue and surrounding structures around the alveoli and airways)
They often cause inflammation and fibrosis.
What are the main categories of ILD?
Idiopathic pulmonary fibrosis
Hypersensitivity pneumonitis (extrinsic allergic alveolitis)
Occupational interstitial lung disease (pneumoconiosis)
Pulmonary fibrosis associated with connective tissue disease
Drug induced pulmonary fibrosis
Sarcoidosis
How is interstitial lung disease investigated?
Diagnose needs a high resolution CT scan.
Progression should be monitored with spirometry.
How is interstitial lung disease treated?
- Corticosteroids may be used to help reduce inflammation or other immunosupressive drugs. (Can reverse the damage in early disease)
- Abx if infections are present.
- Mucolytics such as N-acetylcysteine
- Avoidance of allergen in hypersensitivity pneumonitis.
In end stage disease then transplant is the only curative treatment.
In hypersensitivity pneumonitis (extrinsic allergic alveolitis) what is the underlying hypersensitivity reaction?
It can be caused by a:
-Type III immune mediated hypersensitivity reaction.
OR a
-Type IV cell mediated hypersensitivity reaction
How can hypersensitivity pneumonitis be diagnosed?
Suggestive history with positive precipitating antibodies to the offending antigen.
Histopathology from a biopsy or a bronchoalveolar lavage.
What are the common allergens associated with EAA? (7)
Farmer’s lung - one of the most common forms. Due to exposure to mouldy hay.
Bird-fancier’s lung - one of the most common forms. Due to exposure to avian proteins - eg, pigeons, parakeets.
Cheese-worker’s lung - exposure to cheese mould.
Malt worker’s lung - exposure to Aspergillus clavatus in mouldy malt.
Hot tub lung - exposure to Mycobacterium avium in poorly-maintained hot tubs
Chemical worker’s lung
Mushroom worker’s lung - exposure to thermophilic actinomycetes in mushroom compost
Describe the different presentations of EAA?
Acute:
- Symptoms occur 4-6 hours after exposure to antigen
- Flu-like illness with fever, chest tightness, dry cough, dyspnoea and malaise.
- Signs include bi-basal fine inspiratory crackles
- Severity often correlates with amount of exposure to an antigen
Subacute:
- Symptoms are less severe and more gradual in onset but similar in nature to acute presentations
- It can present as a recurrent pneumonia
Chronic:
- Few systemic symptoms other than weight loss and reduced exercise tolerance
- May present with exacerbations
What are the complications of repeated exposure to a causative organism in hypersensitivity pneumonitis?
Repeated inflammation causing fibrosis which may be permanent.
May develop respiratory failure due to the restrictive pathology.
May eventually develop cor pulmonale due to increased pulmonary vasculature resistance.
What is the main stay of treatment in EAA?
Avoidance/removal of antigens.
Acute reactions tend resolve spontaneously once the antigen has been removed.
In sub acute/chronic presentations steroids or other immunoupressive drugs may be needed.
Describe the main conditions associated with asbestos inhalation?
Pleural plaques: benign plaques which become deposited on the pleura in the lower regions of the pleura. They are usually asymptomatic but may cause chest pain. Common in people with asbestos exposure (20-60%)
Asbestosis: is fibrosis of the lung due to irritation by inhaled asbestos particles. It is a progressive disease characterised by:
Dysopnea
Clubbing
Bilateral basal end inspiratory crackles.
Mesotheliomas are aggressive malignancies of the pleural cells caused by inhalation of asbestos (particularly crocolodite)
Typically their is a 20-40 year lag between exposure and development of the cancer.
Discuss the pathology and classification of simple coal workers pneumoconiosis and progressive massive fibrosis?
Coal workers pneumoconiosis is a disease caused by the inhalation of coal particles (particularly silica) of 2-5u in diameter.
It is classified into categories 1-3 depending on the amount of fine micronodular shadowing on CXR and Progressive Massive Fibrosis (PMF).
PMF is a progressive fibrotic disorder.
Initially patients will get black fibrotic masses in the apices, followed by apical destruction.
The damage is due to type III hypersensitivity (Immune complexes) and causes a obstructive and restrictive ventilatory defect.
Important to ask about occupational hx as the patients may be able to receive compensation.
