What is the interstitial space?
A potential space between alveolar cells and the capillary basement membrane, which is only apparent in disease states
What may the interstitial space contain in disease states?
Fibrous tissue, cells, or fluid
What is interstitial lung disease?
A group of diseases with a variety of causes, that all have similar pathological effects and clinical features
What is the pathophysiology of interstitial lung disease?
The development of fibrous tissue in the intersticium, producing a restrictive ventilatory defect
Why does the development of fibrous tissue in the intersticium produce a restrictive ventilatory defect?
Because it makes the lungs less compliant
Is airway resistance increased in interstitial lung disease?
How can the FEV1/FVC ratio be kept >70% in interstitial lung disease?
Due to increased radial traction on the airway keeping the airway open
What impairs gas exchange in interstitial lung disease?
Lengthening of the diffusion path
What is selectively affected in interstitial lung disease?
Why is oxygen uptake selectively affected in interstitial lung disease?
As CO2 diffuses much more readily
What are the symptoms of interstitial lung disease?
- Shortness of breath
- Reduced exercise tolerance
- Dry cough
What are the signs of interstitial lung disease?
- Reduced chest movement bilaterally
- Coarse crackles
What signs may be present in interstitial lung disease?
- Signs of right heart failure
When is clubbing seen in interstitial lung disease?
Cryptogenic fibrosing alveolitis
What are the categories of causes of interstitial lung disease?
- Treatment related
- Connective tissue disease
What are the occupational causes of interstitial lung disease?
- Coal workers pneumoconiosis
What are the treatment related causes of interstitial lung disease?
What connective tissue diseases can cause interstitial lung disease?
- Rheumatoid arthritis
What are the immunological causes of interstitial lung disease?
- Hypersensitivity pneumonitis (EAA)
What are the idiopathic causes of interstitial lung disease?
- COP (BOOP)
CFA- cryptogenic fibrosing alveolitis
IPF- idiopathic pulmonary fibrosis
UIP- usual interstitial pneumonia
NSIP- non-specific interstial pnuemonia
DIP- desquamative interstial pneumonia
LIP- lymphoid interstitial pnuemonia
RBILD- respiratory bronchiolitis interstiial lung disease
COP- crytogenic organising pneumonia
BOOP- bronchiolitis oblitirans organising pneuomnia
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What is fibrosing alveolitis?
A progressive inflammatory condition of an unknown cause
How common is fibrosing alveolitis?
Relatively rare, 3-5 cases per 100,000
How does the incidence of fibrosing alveolitis differ between the sexes?
It is two times more common in males
What are the histological features of fibrosing alveolitis?
Increased activated alveolar macrophages
What is the effect of increased activated alveolar macrophages in fibrosing alveolitis?
- Attract neutrophils and eosinophils
- Local lung damage
- Tissue destruction and fibrosis
Why do increased alveolar macrophages lead to local lung damage?
Due to ROS and proteases
What do patients report with fibrosing alveolitis?
Progressive shortness of breath on exercise, often with non-productive cough
Do patients with fibrosing alveolitis have finger clubbing?
What does the chest x-ray show in patients with fibrosing alveolitis?
Small lungs with micro-nodular shadowing predominating in the lower lobes, with ragged heart borders
When can fibrosing alveolitis be restrained?
In the early stages, less effective once fibrosis has developed