restrictive lung disease Flashcards
in restrictive lung disease, what is the lung volume
small
examples of extrinsic disorders
compress lungs or limit expansion
-Pleural
-Chest wall
what is an example of Intrinsic lung disease
alterations to lung parenchyma
interstitial lung disease (ILD)
what is lung parenchyma
alveolar region of lung
what is Interstitial space
space between alveolar epithelium and capillary endothelium.
-lymphatic vessels, fibroblasts, ECM.
-Structural support to lung
-Very thin for gas exchange
what is Alveolar type 2 epithelial cell
surfactant to reduce surface tension, stem cell for repair
what is Alveolar type 1 epithelial cell
gas exchange surface
what is Fibroblasts
produce ECM e.g Collagen type 1
some types of interstitial lung disease
idiopathic-idiopathic pulmonary fibrosis
auto-immune related- systemic sclerosis
exposure related-hypersensitivity pneumonitis
with cysts/airspace filling
sarcoidosis
Investigations in ILD
-Blood tests e.g. (ANA), (RhF), (CCP)
-6-minute walk test
-High resolution CT scan
-invasive= surg-lung biopsy
Lung physiology in ILD- what is?
-Lung volumes (TLC, FRC, RV),
-FVC,
-diffusing capacity of lung for carbon monoxide (DLCO),
-arterial PO2
-FEV1/ FVC ratio
↓ Lung volumes (TLC, FRC, RV)
↓ FVC
↓ diffusing capacity of lung for carbon monoxide (DLCO)
↓ arterial PO2 – particularly with exercise
Normal or ↑ FEV1/ FVC ratio (0.8+)
what can be seen in [usual interstitial pneumonia] - HRCT vs histopathology
usually in IPF:
HRCT:
honeycombing on peripheral/base of lungs
Histopathology- microscopic honeycomb cyst +
fibroblastic foci-> proliferating fibroblast= active disease
what can be seen in [organising pneumonia]
ground glass opacities- alveoli filled with a bit of fluid
consolidation- alveoli completely filled with fluid
what are the proposed predisposing factors for IPF
Genetic susceptibility
-MUC5B, DSP
Environmental triggers
-smoke, viruses, pollutants, dusts
Cellular ageing
-telomere attrition, senescence
pathology pathway for IPF
- alveoli injury
- profibrotic macrophage/fibroblast produce a lot of ECM-> accumulates.
- remodelling + honeycomb cyst form
- interstitial thickens, gas exchange not as effective
what can be seen in IPF on CT- in relation to bronchi
traction bronchiectasis = bronchi widening/dilating
what should you NOT prescribe in IPF and why
Immunosuppressants - ie. prednisone + azathioprine +N-acetylcysteine
increase risk of death
IPF treatment
antifibrotics
-nintedanib - tyrosine kinase inhibitor
-pirfenidone
what is hypersensitivity pneumonitis and where it involves
immune- mediated response in sensitised individuals to inhaled environmental antigens (ie. bird droppings)
small airways and parenchyma
what are the 2 types of HP and what are they
Acute HP -
-Intermittent, high exposure.
-Sudden onset, flu-like syndrome 4-12 hrs after exposure
-ie. holiday- contact with animal faecels
Chronic HP -
-Long-term, low-level exposure
-Nonfibrotic (purely inflammatory)
-Fibrotic – associated with higher mortality
-ie. bird keeper
explain the immunological dysregulation behind hypersensitivity pneumonitis
1.Antigen exposure
2.innate immune system
Inflammatory response mediated by T-helper cells and Ig-G antibodies
3.Accumulation of lymphocytes and formation of granulomas
how to diagnose HP
-hx
-inspiratory squeaks- from bronchiolitis
-IgG antibodies
-HRCT- air trapping/ground -glass nodules
-bronchoalveolar lavage lymphocyte count 30%+
-HRCT- air trapping/ground -glass nodules - what are the cause in HP
ground glass= interstitial inflammation
air-trapping= narrowing of small airways
HP treatment
-antigen removal
-corticosteroids
-immunosuppressants- but poor evidence based
-progressive-> fibrotic HP= nintedanib (antifibrotic)
