Restrictive Lung Disease Flashcards
What is restrictive lung disease?
Diseases which make the lung volume small by restricting their expansion
What is intrinsic lung disease?
- alteration in lung parenchyma
- interstital lung disease
What is extrinsic lung disease?
- compression or limited expansion of lungs
- pleural, chest wall or neuromuscular
What is the lung parenchyma?
alveolar region of the lungs
What does the lung parenchyma consist of
- alveolar type 1 epithelial cell
- alveolar type 2 epithelial cell
- fibroblasts
- alveolar macrophages
What do alveolar epithelial cells do?
- type 1 = gas exchange surface
- type 2 = surfactant to reduce surface tension and stem cells for repair
What do fibroblasts do?
produce ECM
What do alveolar macrophages do?
- phagocytosis or foreign material
- produce surfactant
What is the interstital space?
space between alveolar epithelium and capillary endothelium
What is the function of the interstital space?
- contains lymphatic vessels, fibroblasts and ECM
- structural support for lungs
- very thin to facillitate gas exchange
What are the different types of ILD?
- idiopathic (IPF)
- autoimmune (CTD)
- exposure related (hypersensitivity pneumonitis)
- and many more (200+)
What is ILD?
inflammation or fibrosis of the interstitial space
What is the presentation of ILD?
- Progressive breathlessness
- Non-productive cough
- Limitation in exercise tolerance
- Symptoms of connective tissue disease?
- Occupational and exposure history
- Medication history (drug induced ILD)
- Family history (up to 20% of idiopathic ILDs are familial)
What are the clinical findings in ILD?
- low oxygen saturation
- fine bilateral inspiratory crackles
- digital clubbing
- features of connective tissue dieases
What are the investigations for ILD?
- blood tests for anti-nuclear antibody (ANA), rheumatoid factor (RhF), CCP
- pulmonary function test
- 6-minute walk test
- high resolution CT scan
Which invasive tests can be done for ILD?
- bronchoalveolar lavage (BAL)
- surgical lung biopsy (2-4% mortality)
What is the lung physiology in ILD?
- decreased lung volume
- decreased FVC
- decreased diffusing capacity for lung CO (DLCO)
- decreased arterial PO2
- normal or increased FEV1/FVC
What is essential for ILD diagnosis?
- high resolution CT scan
- rotating xrays create high frequency reconstruction from many small slices
- gives good resolution at level of secondary pulmonary lobule
How do high and low density areas appear on a HRCT?
- high density = white
- low density = dark
Which planes are viewed on an HRCT?
- axial
- sagittal
- coronal
What are the three patterns of ILD?
- usual interstitial pneumonia
- non-specific interstitial pneumonia
- organising pneumonia
Which pattern is this?
usual interstitial pneumonia
Which pattern is this?
non-specific interstitial pneumonia
Which pattern is this?
organising pneumonia
What is the treatment of early stage ILD?
- 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
What is the treatment of late stage ILD?
- Supplemental oxygen
- Lung transplantation
- Palliative care – symptom management, end-of-life care
What is idiopathic pulmonary fibrosis?
- Progressive, scarring lung disease of unknown cause
- Incidence increases with age - most >60yrs
- More common in men
- Average decline in forced vital capacity (FVC) = 150 – 200mls / year
What are acute exacerbations of IPF?
- Occur in 5-15% of patients
- Median survival 3-4 months
- In-hospital mortality ~50%
What is the median survival of untreated IPF?
3-5 years
What are the predisposing factors of IPF?
- genetic susceptibility (MUC5B, DSP)
- environmental triggers (smoke, viruses, pollutants, dust)
- cellular aging
What are the characteristic features of IPF on a CT scan?
- subpleural honeycombing
- traction bronchiectasis
- basal predominance
What is harmful for people with IPF?
immunosuppression
What is the treatment for IPF?
- antifibriotics (nintedanib and pirfenidone)
- slows progression but doesn’t cure or reverse damage
What is hypersensitivity pneumonitis?
- ILD caused by immune response to inhaled environmental anitgens
- genetic and host factors contribute to who is susceptible to it
- involves small airways and parenchyma
What are the classifications of HP?
acute and chronic
What is acute HP?
- intermittent, high-level exposure
- abrupt symptom onset
- flu-like symptoms 4-12 hours after exposure
What is chronic HP?
- long-term, low-level exposure
- two types: nonfibrotic and fibrotic
- fibrotic has higher mortality
What is the epidemiology of HP?
- rare
- mean onset age 50-60yrs
- less frequent in smokers
- 3x increase risk of death compared to gen pop
What is HP driven by?
- immune dysregulation
- antigen exposure to the innate immune system leads to inflammatory response from Th and IgG
- leads to accumulation of lymphocytes and granuloma formation
What are some triggers of HP?
- African parrot (droppings)
- hay
- plant and animal proteins
How is HP diagnosed?
- need history as an antigen is not identified in ~50% of patients
- inspiratory squeaks caused by bronchiolitis
- IgG to potential antigens
- HRCT
- BAL lymphocyte count > 30%
What is the treatment of HP?
- complete removal/avoidance of antigen
- corticosteroids
- immunosuppressants
- antifibrotics (e.g. nintedanib) for progressive, fibriotic HP
What are the connective tissue diseases associated with ILD?
systemic sclerois and rheumatoid arthiritis
What is systemic sclerosis?
- autoimmune connective tissue diesease
- immune dysregulation and progressive fibrosis of skin and various internal organs
- rare
- affects young, middle-aged women
- ILD develops in 30-40%
- can progress slowly or quickkly
What are the skin issues which occur in systemic sclerosis?
- sclerodactyly
- raynaud’s
- telengectasias
- digital ulcers
- abnormal nailfold
How is SSc classified based on skin involvement?
- limited cutaneous SSc
- diffuse cutaneous SSc
Which type of SSc is ILD more common with?
Diffuse cutaneous SSc
Which autoantibodies confirm SSc?
- anti-centromere
- anti-Scl-70 (also associated with ILD)
What is the pahtogenesis of SSc-ILD?
- tissue injury
- vascular injury
- autoimmunity
- inflammation
- fibrosis
What are the HRCT patterns in SSc-ILD?
non-specific interstitial pneumonia is the most common
How do you manage SSc-ILD?
- treatment determined by disease extent on HRCT and lung function trajectory
- corticosteroids are high risk for renal crisis
- immunosuppressives (cyclophosphanamide, MMF)
- nintedanib for progressive fibrosis
