Idiopathic Pulmonary Fibrosis Flashcards
Define
Inflammatory condition of the lung resulting in fibrosis of the alveoli and interstitium.
Previously known as cryptogenic fibrosing alveolitis.
Causes
Occurs in genetically predisposed individuals
Recurrent injury to alveolar epithelial cells results in secretion of cytokines and growth factors
This leads to fibroblast activation, recruitment, proliferation, differentiations into myofibroblasts and increased collagen synthesis and deposition
Certain drugs can produce similar illness (e.g. methotrexate, amiodarone)
Histological Patterns
Interstitial pneumonia
Risk factors
Smoking
Occupational exposure to metal or wood
Chronic microaspiration
Animal and vegetable dusts
Epidemiology
RARE
6/100,000
More common in MALES
Symptoms
Gradual-onset, progressive dyspnoea on exertion
Dry irritating cough
NO wheeze
Symptoms may be preceded by a viral-type illness
Fatigue and weight loss are common
IMPORTANT: take a full occupational and drug history
Signs
Clubbing (50%)
Bibasal fine late inspiratory crackles
Signs of right heart failure in advanced stages of disease
Investigations
Bloods
ABG
- Normal in early disease
- PO2 decreases with exercise
- Normal PCO2, which rises in late stage disease
ANA and Rheumatoid Factor
- 1/3 of patients are positive for ANA or RF
CXR
Usually NORMAL at presentation
- Early disease may show ground glass shadowing
- Later stage disease shows reticulonodular shadowing, signs of cor pulmonale and, eventually, honeycombing
High-Resolution CT
- More sensitive in early disease than CXR
Pulmonary Function Tests
- Restrictive features (reduced FEV1 and FVC, with preserved or increased FEV1/FVC)
- Decreased lung volumes
- Decreased lung compliance
- Decreased total lung capacity
- Bronchoalveolar Lavage - exclude infections and malignancy
Lung Biopsy - gold standard for diagnosis
Echocardiography - to check for pulmonary hypertension
