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Cardio > Restrictive Lung Diseases > Flashcards

Restrictive Lung Diseases Flashcards

1
Q

What is restrictive lung disease?

A

Lung volumes are small
Expansion of the lung restricted by……

Intrinsic lung disease -
—alterations to lung parenchyma interstitial lung disease (ILD)

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

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2
Q

What are the important cellular components of the lung parenchyma?

A

Lung parenchyma = the alveolar regions of the lung

Alveolar type 1 epithelial cell – gas exchange surface (approx. 70m2)

Alveolar type 2 epithelial cell – surfactant to reduce surface tension, stem cell for repair

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

Alveolar macrophages – phagocytose foreign material, surfactant

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3
Q

What is the interstitial space?

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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4
Q

What does interstitial lung disease involve?

A

Inflammation or fibrosis in the interstitial space

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5
Q

What are the types of interstitial lung diseases?

A

Idiopathic
Auto-immune related
Exposure related
With cysts or airspaces filling
Sarcoidosis
Others e.g. eosinophilic pneumonia

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6
Q

What is the clinical presentation in terms of history for 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, http://www.pneumotox.com)

Family history (up to 20% of idiopathic ILDs are familial)

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7
Q

What is the clinical presentation in terms of clinical examination in ILD?

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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8
Q

What are the investigations for ILD?

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)

Invasive testing:

—–Bronchoalveolar lavage (BAL)

—–Surgical lung biopsy (2-4% mortality)

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9
Q

Explain the 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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10
Q

Look at patterns of forced expiration**

A
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11
Q

How does a High-resolution CT (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)

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

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12
Q

Look at HRCT patterns in pneumonia**

A
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13
Q

Who in the MDT is involved in diagnosis?

A

Integration of clinical, radiological +/- pathological information to make a diagnosis

Radiologist
Clinical nurse specialist
Physiotherapist/occupational therapist
Pulmonologist
Respiratory physiologist
Pathologist
Rheumatologist

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14
Q

What are the variables evaluated during an MDT?

A

Clinical information
Environmental exposures
Biology and autoimmunity
Familial history / genetic information
PFT
CT
Serological testing
Biopsy
Bronchoscopy / BAL
Longitudinal ILD evolution

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15
Q

What are general principles of ILD management in terms of 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

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16
Q

What are general principles of ILD management in terms of late disease?

A

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

17
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

18
Q

What is the prognosis of IPF?

A

Median untreated survival 3 - 5 years

19
Q

What are the proposed mechanisms of IPF

A

Predisposing factors

Genetic susceptibility
-MUC5B, DSP

Environmental triggers
-smoke, viruses, pollutants, dusts

Cellular ageing
-telomere attrition, senescence

20
Q

What is IPF initiated by?

A

Alveolar epithelial injury

Denuded alveolar epithelium seen by electron microscopy

Targeted injury to AECIIs in mouse model – ↑ collagen deposition

Re-epithelialization disturbed in IPF

21
Q

Look at the histopathology of IPF**

A

Microscopic honeycomb cyst

Fibroblastic foci

22
Q

What are the characteristic features of IPF on CT scan?**

A

Axial plane - subpleural honeycombing
-traction bronchiectasis

Coronal plane- basal predominance

23
Q

What is harmful in IPF?

A

Immunosuppression

24
Q

What do antifibrotics do in IPF?

A

Slows disease progression but do not cure

e.g. nintedanib - tyrosine kinase inhibitor
-pirfenidone - a pyridine compound

25
Q

What do drugs target in fibrotic pathways in clinical trials***

A
26
Q

What is hypersensitivity pneumonitis ?

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

27
Q

What is acute HP?

A

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

28
Q

What is chronic HP?

A

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

29
Q

What is the mean onset age for HP?

Does smoking increases frequency?

A

50-60yrs

Yes

30
Q

How is HP driven by immunological dysregulation?

A

-Antigen exposure and processing by the innate immune system
-Inflammatory response mediated by T-helper cells and antigen-specific immunoglobulin (Ig) G antibodies
-Accumulation of lymphocytes and formation of granulomas

31
Q

Explain the diagnostic work up of 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

32
Q

What is the treatment of HP?

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)

33
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

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

34
Q

What are the clinical features of SSc?

A

Classified based on skin involvement -

limited cutaneous SSc
(Pulmonary hypertension more common)

or

diffuse cutaneous SSc
(ILD more common)

Autoantibodies –
—Anti-centromere
—Anti-Scl-70 - associated with increased with ILD

35
Q

Explain further using images what the clinical features of SSc are? ***

A

Sclerodactyly
Raynaud’s
Telengectasias
Abnormal nailfold capillaroscopy
Digital ulcer

36
Q

Explain the pathogenesis of ILD?***

A

Tissue injury
Vascular injury
Autoimmunity
Inflammation
Fibrosis

37
Q

What are HRCT patterns in SSc-ILD?**

A

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

38
Q

What is the management of SSc-ILD?

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

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