Interstitial Lung Disease Flashcards
Define Interstitial Lung disease
‘Diffuse Lung Disease’
Umbrella term for multiple conditions - similar clinical, radiological, physiological and pathological changes
Characteristed by inflammation and fibrosis of the lung parenchyma
What are the most common types of Interstitial Lung Disease?
Idiopathic Pulmonary fibrosis
Hypersensitivity syndromes
Sarcoidosis
How does interstitial lung disease commonly present?
Worsening dysponea - no relief from salbutamol
Cough - non-productive
Fatigue
Weight loss
What is the basic pathophysiology of interstitial lung disease?
Interstitium is the membrane between alveolar epithelium and capillary endothelium
Injury triggers inflammation and fibrosis - fibroblasts cause collagen deposition throughout intersititum forming scar tissue
Increases the diffusion distance - inefficient gas exchange – physiological dead space
V/Q mismatch - not adequately perfused
Lungs become stiff and cannot expand
Alveoli become more destroyed and architecture of the lung is distorted.
What are some potential causes of ILD?
Exposure - gas/fumes, drugs, radiation, dust
Idiopathic - e.g IPF
Autoimmune - Connective tissue disorders - RA, ankylosing spondylisis - important in young people
Sarcoidosis - granuloma clusters due to chronic inflammation
Drugs - methotrexate
Radiation
What are the two main types of exposure related ILD?
How are they different?
Organic dust - causes hypersensitivity pneumonitis
Inorganic dust - causes pneumoconiosis
What are some triggers and types of organic dust exposure ILD?
Causes - pollen, hay, animal hair/feathres, bacteria, fungi etc
All cause hypersensitivity penumonitis such as Farmers Lung, pigeon fanciers lung
What are some common triggers and presentation of inorganic dust related ILD?
Triggers - asbestosis, coal, silica, iron oxide
All cause pneumoconiosis - asbestosis, coal miners lung
What drugs can cause ILD?
Amiodarone (arrhythmias)
Nitrofurantoin (antibiotic for UTI)
Methotrexate (RA)
Chemotherapy
How does ILD tend to present on examination?
Fine inspiratory crackles
Clubbing
What are some common differentials for ILD?
Resp - ILD, COPD< Lung cancer, bronchiectasis, pleural effusion, asthma
Cardiac - HF, valve disease, anaemia
Renal - kidney failure
Neuromuscular - Myasthenia gravis
Iatrogenic - ACE inhibitors
What investigations are often done for ILD?
Bedside = obs
Bloods = FBC, U&Es, Bone profile, CRP, autoimmune screen, ESR, RF, serum ACE
Imaging = CXR, High resolution CT chest (gold standard)
Other = pulmonary function tests, Lung biopsy
What is seen on this CXR?
Reticular shadowing of the lung peripheries and bases
(kinda looks like dust spinrklines over lung surface)
Caused by scar tissue.
Indicates Interstitial Lung Disease
What pathology is indicated on these CT scans?
Honeycombing of the lungs - enlarged air spaces with thick fibrotic walls
Ground glass change - amidarone lung
How does Interstitial Lung Disease present on spirometry?
Restrictive pattern
Lungs are stiff and cannot expand properly - FEV1 and FVC both reduce but FVC quicker - FEV1/FVC ratio tends to remain normal.
Supportive diagnostic test - monitor disease severity.
