1b Restrictive Lung Disease Flashcards
What is a restrictive lung disease?
When the expansion of the lungs is restricted
Lung volumes are small
What are the two types of restrictive lung disease?
Intrinsic Lung Disease
Extrinsic Lung Disease
What does intrinsic lung disease involve?
Alterations to the lung parenchyma = interstitial lung disease
What does extrinsic lung disease involve?
Compression of the lungs / limiting expansion
- pleural
- chest wall
- neuromuscular = decreases the ability of the respiratory muscles to inflate / deflate the lungs
What is the lung parenchyma?
The alveolar regions of the lung
What are the four cellular components of the lung parenchyma?
- Alveolar type 1 epithelial cell - they provide the surface area for gas exchange to occur on, most common type
- Alveolar type 2 epithelial cell - they secrete sufactat and also are able to convert into alveolar type 1 cells
- Fibroblasts - secrete ECM like type 2 collagen
- Alveolar macrophages - inject pathogens and also release surfactant
What is the interstitial space?
The space between the alveolar epithelium and the capillary endothelium - provides structural support to the lungs and very thin to facilitate gas exchange
What does the interstitial space contain?
Lymphatic vessels, occasional fibroblasts and ECM
What is the purpose of alveolar type 1 epithelial cells?
Gas exchange surface
What is the purpose of alveolar type 2 epithelial cells?
They release a surfactant to reduce surface tension and are stem cells needed for repair
What do fibroblasts do?
Produce ECM like collage type 1
Which alveolar epithelial cell can differentiate?
Type 2 -> into type 1
What is the purpose of alveolar macrophages?
Phagocytose foreign material, and release surfactantx
Which immune cell are closely associated with the lung epithelium?
Alveolar macrophages
What characterises interstitial lung disease?
inflammation or fibrosis in the interstitial space
What are some causes/ examples of ILD?
Idiopathic
Autoimmune related
Exposure related
With syst or airspace filling
Sarcoidosis
Eosinophilic pneumonia
What is the common history of a patient with Interstitial Lung Disease?
Progressive Breathless
Non-productive cough
Limitations in exercise tolerance
Occupational history
What are the clinical examinations seen in patients with interstitial lung disease?
Low O2 saturations
Fine bilateral inspiratory crackle
Digital clubbing
What is the 6 minute walk test?
make patients walk for 6 minutes and if they desaturate below 88% then this is a good marker of interstital lung disease
What are the main investigations into ILD?
High Resolution CT - look at the pattern of disease
Blood tests e.g. anti-nuclear antibody (ANA), rheumatoid factor (RhF), anti-citrullinated peptide (CCP)
Pulmonary function tests
6 minute walk test
What are the two invasive tests which might be done for a patient with ILD?
- Bronchoalveolar lavage - flood lungs with saline and see how much can / is removed
- Surgical Lung Biospy
Why does the compliance of the lung decrease in ILD?
Scarring makes the lung stiff
What happens to Forced Vital Capacity in ILD?
decreases
What happens to the diffusing capacity of lung for CO in ILD?
Decreases
Diffusion capacity assesses how well a tracer gas in inspired air can cross from the air into the blood.
What happens to the FEV1/FVC ratio in ILD?
Normal or increased
What type of pattern is seen on a HRCT in Interstitial pneumonia?
Honey comb
What pattern is seen on a HRCT in organising pneumonia?
Consolidation = dense white
What are the general principles of ILD management in Early Disease?
Pharmacological treatments
Patient education
Vaccination
Smoking cessation
Treatment of co-morbidities
Pulmonary rehabilitation
What are the general principles of ILD management in late disease?
Supplemental O2
Lung transplant
Palliative Care
What is idiopathic pulmonary fibrosis?
Progressive, scarring lung disease or unknown cause
Which gender is idiopathic pulmonary fibrosis more common in?
Men
What is the average decline in FVC?
150-200mls/year
What is the prognosis of Idiopathic pulmonary fibrosis?
poor, even lower survival rate than many cancers
What are the three predisposing factors of IPF?
Genetic susceptibility (MUC5B, DSP)
Environmental triggers
Cellular Ageing
What is the mechanism of IPF?
Injury to the endothelial lining
Aberrant fibroblast activity
Excess accumulation of ECM
Results in remodelling and honeycomb cyst formation
What effect does remodelling have on the lung?
Honey comb cysts - make the lung less efficient at gas exchange
What event initiates IPF?
Alveolar epithelial injury
Describe the histopathological changes which are seen with IPF?
Microscopic honeycomb cysts
Fibroblastic foci = proliferating myofibroblasts
What are the key features of interstitial lung disease?
fine bibasal inspiratory crackles and finger clubbing, with low oxygen saturations
What used to be the conventional therapy for IPF?
Immunosuppression
What is the most useful treatment for IPF now?
Anti-fibrotics - THEY SLOW PROGRESSION BUT DO MOT CURE
What are two anti-fibrotics?
Nintedanib (tyrosine kinase inhibitor) and Pirfenidone (a pyridine compound)
What us hypersensitivity pneumonitis?
ILD caused by immune mediated response in susceptibile and sensitized individuals to inhaled environmental antigens
What is involved in hypersensivity pneumonitis?
Involves small airways and parenchyma
What are the two different types of hypersensitivity pneumonitis?
Acute HP and Chronic HP
What is the difference between Acute and Chronic HP?
Acute = intermittent, high level exposure with abrupt symptom onset
Chronic = long term, low level exposure, and non-fibrotic = purely inflammatory
fibrotic = associated with higher mortality
What drives the pathophysiology of hypersensitivity pneumonitis?
Immunological dysregulation - involves the innate and adaptive immune system
What mediates the inflammatory response seen in HP?
T-Helper cells and antigen-specific IgG antibodies
What does the immunological dysregulation of HP result in the formation of?
Accumulation of lymphocytes and formation of granulomas
Why is the exposure history so important in the diagnosis of HP?
Antigen is not identified in about half the cases
What can be found in a diagnostic work up of HP?
Inspiratory ‘squeaks’ on auscultation - caused by the coexisting bronchiolitis
Specific circulating IgG antibodies to potential antigens
HRCT
What bronchoalveolar lavage lymphocyte count is a good indicator of HP?
> 30%
What does bronchiolocentric inflammation show on a HRCT
Ground glass nodules
What is the treatment of HP?
- Complete removal of the antigen
- Use corticosteriods
- Immunsuppresants such as MMF and azathioprine
- if progressive and fibrotic, use Nintedanib = anti-fibrotic
What is SSc associated ILD?
An autoimmune connective tissue disease characterised by dysregulation and progressive fibrosis that affects the skin, with variable internal organ involvment
Who does SSc ILD effect?
Young, middle aged women
What are the clinical features of SSc\?
Raynaud’s
Sclerodactyly
Abnormal nail fold capillaroscopy
Digital Ulcer
Telengectasias - broken small blood vessels near the surface of the skin
What is the difference between limited cutaneous SSc and Diffuse SSc?
Limited = only skin involvement up to elbows, diffuse = involves the whole body
What is different about SSc compared to other ILD’s?
SSc has a vascular component
What HRCT is seen in SSc-ILD?
Non-specific interstitial pneumonia (NSIP) pattern is the most common pattern
What determines which treatment is given for SSc-ILD?
Determined by disease extent on HRCT and lung function trajectory (monitor every 3 – 6 months)
What are the management options for SSc-ILD?
corticosteroid use is controversial and risk of renal crisis with high doses (>10mg/day)
Immunosuppressives – cyclophosphamide, mycophenolate mofetil (MMF)1
Progressive fibrotic phenotype– Nintedanib (antifibrotic)2
What is the difference in FEV1/FVC and the ratio. between restrictive and obstructive conditions?
restrictive: FEV1 and FVC are both low, therefore the ratio is high
obstructive = even lower FEV1, so ratio is low
What anti-fibrotic is used to treat idiopathic pulmonary fibrosis?
pirfenidone
what are common exam question indications of HP?
Bird droppings, and rat faeces
What are the three CT scan things which are associated with HP?
Chronic honeycombing, ground glass and traction bronchiectasis
What are the auto antibodies associated with Limited Cutaenous SSc?
Anti-Centromere
What is the auto-antibody associated with Diffuse Cutaenous SSc?
Anti-Scl70
How to differentiate between Limited and Diffuse SSc?
Limited = Raynauds
Diffuse = fibrosis
