Restrictive Lung Disease Flashcards
1
Q
What is restrictive lung disease?
A
Diseases which make the lung volume small by restricting their expansion
2
Q
What is intrinsic lung disease?
A
- alteration in lung parenchyma
- interstital lung disease
3
Q
What is extrinsic lung disease?
A
- compression or limited expansion of lungs
- pleural, chest wall or neuromuscular
4
Q
What is the lung parenchyma?
A
alveolar region of the lungs
5
Q
What does the lung parenchyma consist of
A
- alveolar type 1 epithelial cell
- alveolar type 2 epithelial cell
- fibroblasts
- alveolar macrophages
6
Q
What do alveolar epithelial cells do?
A
- type 1 = gas exchange surface
- type 2 = surfactant to reduce surface tension and stem cells for repair
7
Q
What do fibroblasts do?
A
produce ECM
8
Q
What do alveolar macrophages do?
A
- phagocytosis or foreign material
- produce surfactant
9
Q
What is the interstital space?
A
space between alveolar epithelium and capillary endothelium
10
Q
What is the function of the interstital space?
A
- contains lymphatic vessels, fibroblasts and ECM
- structural support for lungs
- very thin to facillitate gas exchange
11
Q
What are the different types of ILD?
A
- idiopathic (IPF)
- autoimmune (CTD)
- exposure related (hypersensitivity pneumonitis)
- and many more (200+)
12
Q
What is ILD?
A
inflammation or fibrosis of the interstitial space
13
Q
What is the presentation of ILD?
A
- 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)
14
Q
What are the clinical findings in ILD?
A
- low oxygen saturation
- fine bilateral inspiratory crackles
- digital clubbing
- features of connective tissue dieases
15
Q
What are the investigations for ILD?
A
- blood tests for anti-nuclear antibody (ANA), rheumatoid factor (RhF), CCP
- pulmonary function test
- 6-minute walk test
- high resolution CT scan
16
Q
Which invasive tests can be done for ILD?
A
- bronchoalveolar lavage (BAL)
- surgical lung biopsy (2-4% mortality)
17
Q
What is the lung physiology in ILD?
A
- decreased lung volume
- decreased FVC
- decreased diffusing capacity for lung CO (DLCO)
- decreased arterial PO2
- normal or increased FEV1/FVC
18
Q
What is essential for ILD diagnosis?
A
- high resolution CT scan
- rotating xrays create high frequency reconstruction from many small slices
- gives good resolution at level of secondary pulmonary lobule
19
Q
How do high and low density areas appear on a HRCT?
A
- high density = white
- low density = dark
20
Q
Which planes are viewed on an HRCT?
A
- axial
- sagittal
- coronal
21
Q
What are the three patterns of ILD?
A
- usual interstitial pneumonia
- non-specific interstitial pneumonia
- organising pneumonia
22
Q
Which pattern is this?
A
usual interstitial pneumonia
23
Q
Which pattern is this?
A
non-specific interstitial pneumonia
24
Q
Which pattern is this?
A
organising pneumonia
25
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
26
What is the treatment of late stage ILD?
* Supplemental oxygen
* Lung transplantation
* Palliative care – symptom management, end-of-life care
27
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
28
What are acute exacerbations of IPF?
* Occur in 5-15% of patients
* Median survival 3-4 months
* In-hospital mortality ~50%
29
What is the median survival of untreated IPF?
3-5 years
30
What are the predisposing factors of IPF?
- genetic susceptibility (MUC5B, DSP)
- environmental triggers (smoke, viruses, pollutants, dust)
- cellular aging
31
What are the characteristic features of IPF on a CT scan?
- subpleural honeycombing
- traction bronchiectasis
- basal predominance
32
What is harmful for people with IPF?
immunosuppression
33
What is the treatment for IPF?
- antifibriotics (nintedanib and pirfenidone)
- slows progression but doesn't cure or reverse damage
34
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
35
What are the classifications of HP?
acute and chronic
36
What is acute HP?
- intermittent, high-level exposure
- abrupt symptom onset
- flu-like symptoms 4-12 hours after exposure
37
What is chronic HP?
- long-term, low-level exposure
- two types: nonfibrotic and fibrotic
- fibrotic has higher mortality
38
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
39
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
40
What are some triggers of HP?
- African parrot (droppings)
- hay
- plant and animal proteins
41
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%
42
What is the treatment of HP?
- complete removal/avoidance of antigen
- corticosteroids
- immunosuppressants
- antifibrotics (e.g. nintedanib) for progressive, fibriotic HP
43
What are the connective tissue diseases associated with ILD?
systemic sclerois and rheumatoid arthiritis
44
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
45
What are the skin issues which occur in systemic sclerosis?
- sclerodactyly
- raynaud's
- telengectasias
- digital ulcers
- abnormal nailfold
46
How is SSc classified based on skin involvement?
- limited cutaneous SSc
- diffuse cutaneous SSc
46
Which type of SSc is ILD more common with?
Diffuse cutaneous SSc
47
Which autoantibodies confirm SSc?
- anti-centromere
- anti-Scl-70 (also associated with ILD)
48
What is the pahtogenesis of SSc-ILD?
- tissue injury
- vascular injury
- autoimmunity
- inflammation
- fibrosis
49
What are the HRCT patterns in SSc-ILD?
non-specific interstitial pneumonia is the most common
50
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
