Restrictive (interstitial lung disease) Flashcards
What type of disease are interstitial diseases?
Inflammatory
What is the interstitium of the lung
Between the alveolar cell wall and the basement membrane of the endothelial cell from the capillary
What is normal interstitium like? Why?
Usaully no/very little space, alveolar cell and endothelial cells are stuck tightly together for optimum gas diffusion.
What are the unifying feature of interstitial lung disease?
Causes restrictive lung defect
Occurs within the interstitial part of lung
Most occur throughout the whole lung
Why do they get a restrictive reading?
Because the inflammation stiffens the lung and so lung is unable to expand as much and therefore also isn’t able to get as much air in, despite there still being the same amount of elastic fibres.
Is there loss of elastic tissue in interstitial lung disease?
No
How can you think about interstitial lung disease?
A rope tied to an elastic band, the elastic fibres are still there and able to expand and contract, however the rope (inflammation and fibrous tissue)is the restricting part.
What readings for FEV1/FVC
Both reduced, but the ratio can sometimes be increased
Clinical symptoms of interstitial lung disease?
Usually not many and can often only be discovered due to a scan (CXR/CT) for other conditions.
Otherwise will present later with SOB on exertion, then later stages present with SOB at rest.
Can have Type 1 respiratory failure and heart failure
How is it discovered?
CXR/CT
Xray on max inhalation Emphysema vs interstitial
Emphysema = large lung volume visable (long and thin), interstitial = reduced lung volume (length) - just can’t expand as lungs are so stiff
What impact can chronic inflammatory responses lead to?
fibrosis of the lung
The more likely the process of ………., the more likely to lead to end-stage honeycomb?
fibrosis
What is DAD/? or DADS?
Diffuse alveolar damage or Diffuse Alveolar Damage Syndrome, its the pathological process for acute interstitial lung disease
What can cause DAD?
Any form of acute injury to the alveolar.
Can be due to: Major trauma Chemical injury/toxic inhalation Circulatory shock Drugs Infection (inc. viruses inc. SARS Cov1 and SARSCov2) Autoimmune disease Radiation
And can be Idiopathic (unknown cause)
what happens in Diffuse Alveolar Damage (DAD) - timescale?
first day or 2 = MASSES of swelling (oedema) from plasma of capillaries
days 3-6 hyaline membranes - plasma proteins line the alveoli.
day 7/8+ - interstitial inflammation is maximized, with interstitial fibrosis not far behind
What causes Hyaline membranes?
Plasma proteins lining alveolar
What does hyaline membrane look like?
pink and clear lining
What is the result of DADS?
A chaotic repair process that results in severe lung damage and extensive fibrosis
Why do DAD patients often die with type 1 respiratory failure?
Because the Oedema can be severe and widespread.
What type of chronic interstitial lung disease is sarcoidosis?
Granulomatosis
What is sarcoidosis?
The most common chronic interstitial lung disease (still relatively rare)
Type 4 hypersensitivity reaction (T cell hypersensitivity) causing epitheliod and giant cell granulomas which do not have necrosis. They are found throughout the body, prevalently in the lung interstitium.
How do we distinguish sarcoidosis to eg TB
sardoidosis granulomas gearally do not have necrosis, whereas TB/ other infective granulomas do
Who is usually affected by sarcoidosis and where is it most prevelant?
Most prevalent in temperate climates (including the UK).
Prevalence highest in African ethnicity living in a temperate climate.
Commonly affects young adults, females more than males.
Main organs involved in sarcoidosis?
Lymph nodes (almost 100% cases) Lung (>90) Spleen (75) Liver (70) Skin/Eyes/Skeletal muscle (50) Bone marrow (20) Salivary Glands (up to 50% cases)
How is sarcoidosis diagnosed?
Often clinically, often doesn’t need a pathological sample
What type of interstitial inflammation is hypersensitivity pneumonitis?
Granulomatous
What are the main antigens causing Hypersensitivity pneumonitis?
Organic molecules/antigens
Bird/Animal proteins (Faeces/bloom) Thermophilic actinomycetes (micropolyspora faeni/Thermoactinoyces vulgaris) Fungi - Aspergillus spp Chemicals Others
What causes Hypersensitivity pneumonitis?
Type 3 and Type 4 inflammatory responses.
Type 4 leads to production of granulomas
Type 3 leads to chronic interstitial inflammation and Pneumonitis!
Presentation of Hypersensitivity Pneumonitis
Variable dependant on extent on reactivity and dose.
Can present like an acute pneumonia, but more often chronic presentationof gradually deteriorating pulmonary function.
History is KEY - possible exposure to anything in the air they breathe
What hypersensitivity reaction is HP?
Types 3 and 4
Where does HP begin and why?
Centriacinar region as it is inhaled antigens, so this is the area to be affected by the antigen first.
Difference sarcoidosis and HP
Inflammatory process around granulomas in Hypersensitivity Pneumonitis (due to type 3 hypersensitivity in addition to type 4), whereas in sarcoidosis you just get the granuloma.
Where in lung and why?
Tends to be upper zones as clearance mechanisms in upper parts of the lungs are not as efficient as in the lower parts, also inhaled antigens generally en up more in upper parts of lungs.
What is IPF?
Ideopathic pulmonary fibrosis
What type of chronic response is IPF?
Inflammatory
What is usual interstitial pneumonitis and what is it caused by?
The pathological process in the lungs when the patient has Idiopathic Pulmonary Fibrosis = Usual interstitial Pneumonitis.
Can be caused by drugs, viruses and asbestos
Is biopsy necessary to confirm UIP?
No
How long does it take acute vs chronic to get to end stage?
Acute Diffuse Alveolar Damage = can be days/weeks
Progressive disease = months/years
UIP (Usual Interstitial Pneumonia) will usually end up with… and die of. Less common for…??
End stage honeycomb lung
Less common for Sarcoidosis, and Hypersensitivity Pneumonitis (to a lesser extent).
What does UIP (Usual Interstitial Pneumonitis) look like under a microscope throughout the lung? Is there evidence of injury in UIP?
Chronic inflammation, lymphocytes and macrophages.
Type 2 pneumocyte hyperplasia.
Yes, evident to see damage to lung, both new and old injuries.
Clinical presentation of UIP?
Dyspnoea, cough
Basal crackles, Cyanosis, Clubbing
Where does IPS concentrate within the lung?
Posterior and basal parts
Does fibrosis increase chance of getting lung cancers?
Yes
Is there increased or decreased compliance in interstitial lung disease?
Decreased compliance
Will there be a ventilation/perfusion imbalance?
yes
