Restrictive Lung Disease Flashcards
What is a restrictive lung disease?
- Expansion of the lung is restricted decreasing lung volume
What is the aetiology of a restrictive lung disease (2)?
-
Intrinsic lung disease:
- Alterations to lung parenchyma interstitial lung disease (ILD)
-
Extrinsic disorders:
- Compress lungs or limit expansion
- Pleural
- Chest wall
- Neuromuscular (decrease ability of respiratory muscles to inflate / deflate the lungs)
- Compress lungs or limit expansion
What are the important cellular components of the lung parenchyma (4)?
Lung parenchyma: the alveolar regions of the lung
- Alveolar type 1 epithelial cell - gas exchange surface (approx. 70m2)
- Alveolar type 2 epithelial cell - surfactant to reduce surface tension, stem cell for repair
- Fibroblasts - produce extracellular matrix (ECM) e.g Collagen type 1
- Alveolar macrophages - phagocytose foreign material, surfactant
What is the function of the interstitial space (3)?
Interstitial space: space between alveolar epithelium and capillary endothelium
- Contains lymphatic vessels, occasional fibroblasts and ECM
- Structural support to lung
- Very thin (few micrometers thick) to facilitate gas exchange
What is the aetiology of interstitial lung disease (ILD) (6)?
-
Idiopathic
- IPF / NSIP / DIP etc.
-
Autoimmune-related
- CTD associated (RA-ILD, SSc-ILD) etc.
-
Exposure related
- Hypersensitivity pneumonitis (HP) / Drug-induced etc.
- With cysts or airspace filling
- Sarcoidosis
-
Others
- Eosinophilic pneumonia etc.
What is the clinical presentation of interstitial lung disease (ILD) (7 symptoms / 4 signs)?
Symptoms:
* Progressive breathlessness
* Non-productive cough
* Limitation in exercise tolerance
* Symptoms of connective tissue disease
* Occupational and exposure history
* Medication history (i.e. drug induced ILD)
* Family history (up to 20% of idiopathic ILDs are familial)
Signs:
* Low oxygen saturations (resting or exertion)
* Fine bilateral inspiratory crackles
* Digital clubbing
* (+/- features of connective tissue disease - skin, joints, muscles)
Outline the pathophysiology of interstitial lung disease (ILD).
- Scarring makes the lung stiff
- Decreased lung compliance
- Decreased lung volumes (TLC, FRC, RV)
- Decreased FVC
- Decreased diffusing capacity of lung for carbon monoxide (DLCO)
- Decrease arterial PO2 – particularly with exercise
- Normal or increased FEV1/ FVC ratio
What investigations are suggested in suspected interstitial lung disease (ILD) (8)?
-
Blood tests:
- Anti-nuclear antibody (ANA)
- Rheumatoid factor (RhF)
- Anti-citrullinated peptide (CCP)
- Pulmonary function tests
- 6-minute walk test (6MWT) - SpO2 ≤ 88% associated with increased risk of death
- High-resolution CT scan (HRCT)
-
Invasive testing:
- Bronchoalveolar lavage (BAL)
- Surgical lung biopsy (2-4% mortality)
What is a high-resolution CT (HRCT)?
HRCT is essential for ILD diagnosis.
- CT uses X-rays to obtain cross-sectional images
- Rotating X-ray source and detectors spin around the patient gathering data
- HRCT - thin slices and high-frequency reconstruction - gives good resolution at level of secondary pulmonary lobule (smallest functional lung unit identifiable on CT)
- High: density substances e.g. bone absorb more x-rays and appear whiter
- Low: density substances e.g. air absorb few x-rays and appear darker
How is suspected interstitial lung disease (ILD) diagnosed?
- Integration of clinical, radiological +/- pathological information to make a diagnosis
How is early interstitial lung disease (ILD) managed (7)?
- Pharmacological therapy:
- Immunosuppressive drugs
- Antifibrotics
- Clinical trials
- Patient education
- Vaccination
- Smoking cessation
- Treatment of co-morbidities (Gastroesophageal reflux / Obstructive sleep apnoea / Pulmonary hypertension)
- Pulmonary rehabilitation
How is late interstitial lung disease (ILD) managed (3)?
- Supplemental oxygen
- Lung transplant
- Paliative care (symptom management / end-of-life care)
Outline the epidemiology of idiopathic pulmonary fibrosis (IPF) (5).
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
- Progressive, scarring lung disease of unknown cause
- 6,000 new cases diagnosed each year
- 1% of all deaths in UK
- Incidence increases with age - most >60yrs
- More common in men
What are the risk factors of idiopathic pulmonary fibrosis (IPF) (7)?
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
- Genetic susceptibility
- MUC5B
- DSP
- Environmental triggers
- Smoke
- Viruses
- Pollutants
- Dusts
-
Cellular ageing
- Telomere attrition
- Senescence
What is the clinical presentation of idiopathic pulmonary fibrosis (IPF) (7 symptoms / 4 signs)?
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
Symptoms:
* Progressive breathlessness
* Non-productive cough
* Limitation in exercise tolerance
* Symptoms of connective tissue disease
* Occupational and exposure history
* Medication history (i.e. drug induced ILD)
* Family history (up to 20% of idiopathic ILDs are familial)
Signs:
* Low oxygen saturations (resting or exertion)
* Fine bilateral inspiratory crackles
* Digital clubbing
* (+/- features of connective tissue disease - skin, joints, muscles)
Outline the pathophysiology of idiopathic pulmonary fibrosis (IPF) (4).
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
-
IPF is initiated by alveolar epithelial injury
-> Denuded alveolar epithelium seen by electron microscopy - Targeted injury to AECIIs (in mouse model)
- Increased collagen deposition
- Re-epithelialization disturbed in IPF
What investigations are suggested in suspected idiopathic pulmonary fibrosis (IPF) (8)?
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
-
Blood tests:
- Anti-nuclear antibody (ANA)
- Rheumatoid factor (RhF)
- Anti-citrullinated peptide (CCP)
- Pulmonary function tests
- 6-minute walk test (6MWT) - SpO2 ≤ 88% associated with increased risk of death
- CT scan
-
Invasive testing:
- Bronchoalveolar lavage (BAL)
- Surgical lung biopsy (2-4% mortality)
How would the lung histopathology of idiopathic pulmonary fibrosis (IPF) be different from a normal lung pathology (2)?
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
Presence of:
* Microscopic honeycomb cyst
* Fibroblastic foci
How would idiopathic pulmonary fibrosis (IPF) present on a CT scan (3)?
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
- Subpleural honeycombing
- Traction bronchiectasis
- Basal predominance
How is idiopathic pulmonary fibrosis (IPF) management different to the interstitial lung disease (ILD) management?
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
- Immunosuppression eventhough helpful in ILD, it is harmful in IPF
- Antifibrotics slow disease progression in IPF but do not cure
Name 3 drugs currently in trial for the management of idiopathic pulmonary fibrosis (IPF).
Idiopathic pulmonary fibrosis (IPF) is a type of interstitial lung disease (ILD).
What is hypersensitivity pneumonitis (HP)?
- ILD caused by immune - mediated response in susceptible and sensitised individuals to inhaled environmental antigens
What is acute hypersensitivity pneumonitis (HP) (4)?
Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Intermittent
- High-level exposure
- Abrupt symptom onset
- Flu-like syndrome 4-12 hrs after exposure
What is chronic hypersensitivity pneumonitis (HP)? What are the 2 subtypes?
Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Long-term, low-level exposure
- Nonfibrotic (purely inflammatory)
- Fibrotic - associated with higher mortality
Outline the epidemiology of hypersensitivity pneumonitis (HP).
Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Rare -> incidence in UK ~ 1 per 100,000
- Worldwide prevalence varies due to differences in antigen exposure, agricultural, industrial practices etc.
- Mean age onset 50-60 yrs
- M=F
- Less frequent in smokers
- 3- fold increased risk of death compared to general population
What are the risk factors of hypersensitivity pneumonitis (HP) (2)?
Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Genetic susceptibility
- Inhaled environmental factors
Outline the pathophysiology of hypersensitivity pneumonitis (HP).
Hypersensitivity pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Antigen exposure and processing by the innate immune system
- Inflammatory response mediated by T-helper cells and antigen-specific immunoglobulin (Ig) G antibodies
- Accumulation of lymphocytes and formation of granulomas
What is the clinical presentation of hypersensitive pneumonitis (HP) (7 symptoms / 4 signs)?
Hypersensitive pneuomonitis (HP) is a type of interstitial lung disease (ILD).
Symptoms:
* Progressive breathlessness
* Non-productive cough
* Limitation in exercise tolerance
* Symptoms of connective tissue disease
* Occupational and exposure history
* Medication history (i.e. drug induced ILD)
* Family history (up to 20% of idiopathic ILDs are familial)
Signs:
* Low oxygen saturations (resting or exertion)
* Fine bilateral inspiratory crackles
* Digital clubbing
* (+/- features of connective tissue disease - skin, joints, muscles)
What investigations are suggested in suspected hypersensitive pneumonitis (HP) (5)?
Hypersensitive pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Detailed exposure history
- Antigen not identified in ~50%
-
Blood tests:
- IgG antibodies circulating
- Bronchoalveolar lavage (BAL) lymphocyte count >30%
- High resolution CT scan (HRCT)
-
Clinical examination:
- Inspiratory ‘squeaks’ on auscultation
- Caused by the coexisting bronchiolitis
- Inspiratory ‘squeaks’ on auscultation
What is the recommended management of hypersensitive pneumonitis (HP) (non-fibrotic) (3)?
Hypersensitive pneumonitis (HP) is a type of interstitial lung disease (ILD).
- Complete antigen removal / avoidance is crucial
- Corticosteroids often used
- Immunosuppressants e.g. mycophenolate mofetil (MMF) and azathioprine used but poor evidence base
What additional medication is required for fibrotic hypersensitive pneumonitis (HP)?
Hypersensitive pneumonitis (HP) is a type of interstitial lung disease (ILD).
Nintedanib (antifibrotic)
What is systemic sclerosis associated - interstitial lung disease (SSc-ILD)?
- SSc is an autoimmune connective tissue disease characterised by immune dysregulation and progressive fibrosis that affects skin, with variable internal organ involvement
Outline the epidemiology of systemic sclerosis associated - interstitial lung disease (SSc-ILD) (5).
- Rare: 10-50 cases per 1,000,000 per year
- Affects young, middle-aged women
- ILD develops in 30-40% of SS patients and is most common cause of death
- 10-year mortality of 40%
- Slow indolent course vs. rapid progression
- Worse survival when:
- Male
- Older age
- Smoker
- 20% extent on HRCT
- FVC < 70%
What is the clinical presentation of systemic sclerosis associated - interstitial lung disease (SSc-ILD) (5)?
- Sclerodactyly
- Raynaud’s phenomenon
- Telengectasias
- Abnormal nailfold capillaroscopy
- Digital ulcer
Systemic sclerosis associated - interstitial lung disease (SSc-ILD) is classified based on skin involvement. What are the 2 classifications?
- Limited cutaneous SSc -> Pulmonary hypertension more common
- Diffuse cutaneous SSc -> Interstitial lung disease (ILD) more common
What autoanitbodies would be elevated in systemic sclerosis associated - interstitial lung disease (SSc-ILD) (2)?
- Anti-centromere
- Anti-Scl-70
Outline the pathogenesis of systemic sclerosis associated - interstitial lung disease (SSc-ILD).
What HRCT patterns would present in systemic sclerosis associated - interstitial lung disease (SSc-ILD)?
- Non-specific interstitial pneumonia (NSIP) pattern is the most common pattern
What is the management of systemic sclerosis associated - interstitial lung disease (SSc-ILD) (3)?
-
Immunosuppressives:
- Cyclophosphamide
- Mycophenolate mofetil (MMF)
- Nintedanib (antifibrotic) in progressive fibrotic phenotype
- Determined by disease extent on HRCT and lung function trajectory (monitor every 3-6 months)
- Corticosteroid use is controversial and risk of renal crisis with high doses (>10mg/day)