Interstitial Lung Disease Flashcards
what is interstitial lung disease
Generic term to describe a number of conditions that affect the lung parenchyma in a diffuse manner
Characterised by chronic inflammation and/or progressive interstitial fibrosis and share a number of clinical and pathological features
what are the different types of ILD with known cause
Occupational/environmental e.g. asbestosis, berylliosis, silicosis, cotton workers lung (pneumoconiosis)
Drugs – nitrofurantoin, bleomycin, amiodarone, sulfasalazine, busulfan
Hypersensitivity reactions – extrinsic allergic alveolitis
Infections
GORD
what are the different types of ILD associated with systemic disorders
Sarcoidosis
RA
SLE, systemic sclerosis, mixed connective tissue disease, Sjogren’s syndrome
UC, renal tubular acidosis, autoimmune thyroid disease
what are the different idiopathic ILDs?
Idiopathic pulmonary fibrosis
Cryptogenic organising pneumonia
Lymphocytic interstitial pneumonia
what are the shared clinical features of ILDs?
Dry cough
Dyspnoea
Digital Clubbing
Diffuse Inspiratory crackles
what is the most common ILD?
idiopathic pulmonary fibrosis
what are the causes of idiopathic pulmonary fibrosis?
Unknown
Environmental factors
RA, SLE, Systemic sclerosis
Drugs – amiodarone
Risk Factors – smoking, occupation, viruses, GORD, male, age
Familial – pulmonary surfactant mutations
what are the clinical features of idiopathic pulmonary fibrosis?
- Worsen over time
- Dry Coughing
- Progressive SOB
- Cyanosis
- Digital clubbing
- Fine inspiratory crackles
- Over time – significant respiratory failure
what investigations can be done for IPF?
chest imaging
PFT
what features will be present in the imaging of IPF?
o Xray – shadowing at bottom + periphery
o CT – honeycombing + bilateral infiltrates
what is PFT of IPF?
Restrictive pattern
Restricted lung expansion = restrictive lung disease = decreased TLC, decreased FVC, decreased FEV1
what is the treatment of IPF?
- Supportive – Oxygen, rehab, opiates
- Antifibrotic (slow rather than stopping)
- Only definitive treatment is Lung transplant
what is the normal process of alveolar lining repair?
When alveolar lining is damaged, Type 1 pneumocytes release TGB1
TGB1 stimulates Type 2 to stimulate fibroblasts to proliferate and develop into myofibroblasts
Myofibroblasts secrete reticular fibres and elastic fibres
Normally myofibroblasts undergo then undergo apoptosis
what is the inflammatory mechanism causing IPF?
Type 2 over proliferate in repair process and myofibroblasts don’t undergo apoptosis = too much collagen
• Collagen accumulates and thickens interstitial layer – problems with ventilation
• Also causes lungs to become stiff – air struggles to flow in and out
= Restricted lung expansion and loss of alveoli (fluid cysts)
what are the common causes of occupational/environmental pneumoconiosis and who are at risk of those?
- Asbestosis – plumbers, roofers, mechanics, shipyard workers
- Silcosis – miners, sandblasters, stonemasons
- Coal workers lung – inhaled dust
- Berylliosis
- Caplans (RA) – if pneumoconiosis occurs with RA
what are the clinical features of simple occupational pneumoconiosis?
few symptoms, slight xray abnormality
symptoms of complicated occupational pneumoconiosis
o Shortness of breath (exacerbated by exercise) o Cough – dry + severe o Fatigue o Tachypnoea o Loss of appetite + weight loss o Chest pain o Fever o Finger clubbing o Silcolosis (blue skin)
what is the underlying pathophysiology of occupational pneumoconiosis?
- If some particles are very small, travel and get trapped in alveolar ducts and bifurcations
- Attract pulmonary alveolar macrophages – activate inflammation and induce IL-1
- Initiate fibroblasts and collagen production = Scarring
what are the differentials of occupational pneumoconiosis?
COPD
HF
Cardiomyopathy
what investigations can be used for occupational pneumoconiosis?
xray
spirometry
what features will be present in an xray of someone with occupational pneumoconiosis?
o Asbestosis = pleural plaques
o Silicosis = egg shell calcification, fibrotic nodules
o Upper zones affected
what will the PFT of occupational pneumoconiosis?
Restrictive
what is the treatment of occupational pneumoconiosis?
no cure avoidance o Pulmonary rehabilitation o Inhaled corticosteroids o Inhaled bronchodilators o O2 if sats / symptoms indicate it is required o Smoking cessation Lung transplant
Features of Asbestosis
- Straight fibres (white, blue – most fibrogenic, brown)
- Disease correlated to level of exposure but disease can take up to 10-60 years to develop
- Linked to mesothelioma
