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Tara's flashcards 1b > Restrictive Lung Disease > Flashcards

Restrictive Lung Disease Flashcards

1
Q

what is restrictive lung disease

A

Lung volumes are small and expansion of the lung is restricted

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2
Q

What are the types of restrictive lung disease

A

Intrinsic and extrinsic

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3
Q

What is intrinsic lung disease and give example

A

alterations to lung parenchyma.
interstitial lung disease (ILD)

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4
Q

What is extrinsic lung disease and give example

A

compress lungs or limit expansion
Pleural
Chest wall
Neuromuscular (decrease ability of respiratory muscles to inflate / deflate the lungs)

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5
Q

Define lung parenchyma

A

the alveolar regions of the lung

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6
Q

Name 4 components of the lung parenchyma

A

Alveolar type 1 epithelial cell
Alveolar type 2 epithelial cell
Fibroblasts
Alveolar macrophages

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7
Q

What do alveolar type 1 epithelial cells do

A

gas exchange surface (approx. 70m^2)

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8
Q

What do alveolar type 2 epithelial cells do

A

surfactant to reduce surface tension, stem cell for repair

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9
Q

What do fibroblasts do

A

produce extracellular matrix (ECM) e.g Collagen type 1

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10
Q

What do alveolar macrophages do

A

phagocytose foreign material, surfactant

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11
Q

What is interstitial space and its purpose

A

space between alveolar epithelium and capillary endothelium.
- Contains lymphatic vessels, occasional fibroblasts and ECM
- Structural support to lung
- Very thin (few micrometers thick) to facilitate gas exchange

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12
Q

What are macrophages closely associated with

A

Lung epithelium

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13
Q

What do interstitial lung diseases involve

A

Inflammation or fibrosis in the interstitial space

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14
Q

What are the classifications of ILDs

A

Idiopathic - IPF, NSIP, DIP etc.
Autoimmune related - CTD associated (RA-ILD, SSc-ILD) etc.
Exposure related - Hypersensitivity pneumonitis (HP), drug-induced etc.
With cysts or airspace filling
Sarcoidosis
Others - Eosinophilic pneumonia etc

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15
Q

Key points in ILD history

A

Progressive breathlessness
Non-productive cough
Limitation in exercise tolerance
Symptoms of connective tissue disease?
Occupational and exposure history
Medication history (drug induced ILD. antibiotics, particularly nitrofurantoin.
immunosuppressant drugs, such as methotrexate)
Family history (up to 20% of idiopathic ILDs are familial)

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16
Q

Features of ILD in clinical examination

A

Low oxygen saturations (resting or exertion)
Fine bilateral inspiratory crackles
Digital clubbing
(+/- features of connective tissue disease – skin, joints, muscles)

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17
Q

ILD investigations

A
  • Blood tests e.g. anti-nuclear antibody (ANA), rheumatoid factor (RhF), anti-citrullinated peptide (CCP)
  • Pulmonary function tests
  • 6-minute walk test (6MWT) – SpO2 ≤ 88% associated with increased risk of death
  • High-resolution CT scan (HRCT) (Essential for ILD diagnosis)
    Invasive testing:
  • Bronchoalveolar lavage (BAL)
  • Surgical lung biopsy (2-4% mortality)
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18
Q

Lung physiology in ILD

A

Scarring makes the lung stiff - ↓ lung compliance

↓ Lung volumes (TLC, FRC, RV)

↓ FVC

↓ diffusing capacity of lung for carbon monoxide (DLCO)

↓ arterial PO2 – particularly with exercise

Normal or ↑ FEV1/ FVC ratio

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19
Q

How does HRCT work

A

CT uses X-rays to obtain cross-sectional images
Rotating X-ray source and detectors spin around the patient gathering data
HRCT - thin slices and high-frequency reconstruction – gives good resolution at level of secondary pulmonary lobule (smallest functional lung unit identifiable on CT)

20
Q

High vs low density substances on HRCT

A

High - density substances e.g. bone absorb more x-rays and appear whiter
Low - density substances e.g. air absorb few x-rays and appear darker

21
Q

HRCT patterns

A

Usual interstitial pneumonia
Non-specific interstitial pneumonia
Organising pneumonia

22
Q

ILD management in early disease

A

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

23
Q

ILD management in late disease

A

Supplemental oxygen
Lung transplantation
Palliative care – symptom management, end-of-life care

24
Q

What is idiopathic pulmonary fibrosis (IPF)

A

Progressive, scarring lung disease of unknown cause
6,000 new cases diagnosed each year
1% of all deaths in UK
Incidence increases with age - most >60yrs
More common in men
Average decline in forced vital capacity (FVC) = 150 – 200mls / year

25
Q

Acute exacerbations of IPF (AE-IPF)

A

Occur in 5-15% of patients
Median survival 3-4 months
In-hospital mortality ~50%

26
Q

Median untreated IPF survival

A

3-5 years

27
Q

IPF predisposing factors

A

Genetic susceptibility
-MUC5B, DSP

Environmental triggers
-smoke, viruses, pollutants, dusts

Cellular ageing
-telomere attrition, senescence

28
Q

IPF mechanisms

A
  1. Altered microbiome
  2. Injury
  3. Alveolar epithelial cell dsyfunction and aberrant fibroblast activity
  4. Excess ECM accumulation
  5. Remodelling and honeycomb cyst formation
29
Q

What medication is harmful in IPF

A

immunosuppression

30
Q

IPF treatment

A

Antifibrotics - they slow down but don’t cure
Nintedanib - tyrosine kinase inhibitor
Pirfenidone – a pyridine compound

31
Q

Drugs targeting fibrotic pathways in clinical trials

A

Galectin-3 inhibitor - TD139 combats injury
Cell based therapies targets epithelial cells

32
Q

What is hypersensitivity pneumonitis (HP)

A

ILD caused by immune- mediated response in susceptible and sensitised individuals to inhaled environmental antigens
Genetic and host factors may explain why only few exposed individuals get HP
Involves small airways and parenchyma

33
Q

HP classifications

A

Acute HP - Intermittent, high-level exposure – abrupt symptom onset, flu-like syndrome 4-12 hrs after exposure

Chronic HP - Long-term, low-level exposure
Nonfibrotic (purely inflammatory)
Fibrotic – associated with higher mortality

34
Q

HP epidemiology

A

Rare - incidence in UK ~ 1 per 100,000
Mean age onset 50 – 60 yrs
M = F
Less frequent in smokers
Worldwide prevalence varies due to differences in antigen exposure, agricultural, industrial practices etc.
3- fold ↑ risk of death compared to general population

35
Q

HP pathophysiology

A

Driven by immunological dsyregulation
- Antigen exposure and processing by the innate immune system
- Inflammatory response mediated by T-helper cells and antigen-specific IgG antibodies
- Accumulation of lymphocytes and formation of granulomas

36
Q

HP environmental antigens

A

Mouldy hay and straw
Humidifiers
Outdoor hot tubs
Birds (also feather pillows)
Rats
Paint/varnish

37
Q

Diagnosing HP

A

Detailed exposure history – antigen not identified in ~50%1

Inspiratory ‘squeaks’ on auscultation - caused by the coexisting bronchiolitis

Specific circulating IgG antibodies (serum precipitins) to potential antigens

HRCT

Bronchoalveolar lavage (BAL) lymphocyte count >30%2

38
Q

HP treatment

A

Complete antigen removal / avoidance is crucial

Corticosteroids often used

Immunosuppressants e.g. mycophenolate mofetil (MMF) and azathioprine used but poor evidence base

Progressive, fibrotic HP – Nintedanib (antifibrotic)1

39
Q

What is systemic sclerosis associated (SSc) - ILD

A

SSc is an autoimmune connective tissue disease characterised by immune dysregulation and progressive fibrosis that affects skin, with variable internal organ involvement
Rare - 10 – 50 cases per 1,000,000 per year
Affects young, middle-aged women
ILD develops in 30-40 % and is most common cause of death – 10-year mortality of 40%
Slow indolent course vs. rapid progression
Male, older age, smoker, >20% extent on HRCT, FVC <70%  worse survival

40
Q

Types of SSc

A

limited cutaneous SSc
(Pulmonary hypertension more common)

or

diffuse cutaneous SSc
(ILD more common)

41
Q

What is CREST

A

Associated with limited cutaneous SSc
Calcinosis - Ca deposits in skin
Raynaud’s
Esophageal dysfunction (acid reflux, decreased motility)
Sclerodactyly - thickening and tightening of skin on fingers and hands
Telangiectasias - dilated capillaries causing red marks on skin

42
Q

Other clinical features of SSc

A

Abnormal nailfold capillaroscopy
Digital ulcer

43
Q

SSc autoantibodies

A

Anti-centromere (more limited)
Anti-scl-70 (more diffuse)

44
Q

Diffuse vs limited SSc

A

Limited = distal skin involvement.
Diffuse = Trunk outwards skin involvement

45
Q

Pathogenesis of SSc-ILD

A

Tissue injury (genetic predisposition, oxidative stress)
Vascular injury
Autoimmunity
Fibrosis
Inflammation

46
Q

HRCT patterns in SSc-ILD

A

Non-specific interstitial pneumonia (NSIP) pattern is the most common pattern

47
Q

SSc-ILD management

A

Determined by disease extent on HRCT and lung function trajectory (monitor every 3 – 6 months)
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

Tara's flashcards 1b (9 decks)

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