Restrictive (Interstitial) Lung Diseases Flashcards

1
Q

What is the interstinum of the lung?

A

The connective tissue space around the airways and vessels and the space between the basement membrane of the alveolar walls

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2
Q

What is true of normal alveolar wall?

A

Most of the alveolar epithelial and interstitial capillary endothelial cell basement membranes are in direct contact

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3
Q

How does restrictive lung diseases affect compliance?

A

Reduced lung compliance (stiff lungs)

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4
Q

How are FEV1 and FVC values affected by restrictive lung diseases?

A
  • Low FEV1
  • Low FVC
  • FEV1/FVC ratio remains normal
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5
Q

How is gas transfer affected in restrictive lung disease?

A
  • Reduced gas transfer

- Diffusion abnormality

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6
Q

How is ventilation/perfusion affected by restrictive lung disease?

A
  • Ventilation/perfusion imbalance

- When small airways affected by pathology

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7
Q

How is diffuse lung disease normally discovered?

A

Discovery of abnormal chest X-ray

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8
Q

What is the main symptom of restrictive lung disease?

A
  • Dyspnoea

- Shortness of breath on exertion progresses to shortness of breath at rest

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9
Q

What do people with restrictive lung disease often develop?

A
  • Type I respiratory failure

- Heart failure

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10
Q

What normally starts the process of restrictive lung disease

A

Parenchymal lung injury

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11
Q

How can a parenchymal lung injury progress?

A
  • Acute response
  • Chronic response
  • Acute response which progresses to a chronic response
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12
Q

What are the ‘3’ responses to a chronic response?

A
  • Usual interstitial pneumonitis (UIP)
  • Granulomatous responses
  • Other patterns
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13
Q

What is an example of an acute response?

A

Diffuse alveolar damage (DAD)

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14
Q

What are other names for DAD?

A
  • ARDS

- Shock lung

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15
Q

What are the causes of DAD?

A
  • Major trauma
  • Chemical injury/toxic inhalation
  • Circulatory shock
  • Drugs
  • infection
  • Autoimmune disease
  • Radiation
  • Idiopathic
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16
Q

What are the histological features of DAD?

A
  • Protein rich oedema
  • Fibrin
  • Hyaline membranes
  • Denuded basement membranes
  • Epithelial proliferation
  • Fibroblast proliferation
  • Scarring- interstitium and airspaces
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17
Q

What are examples of granulomatous responses?

A
  • Sarcoidosis

- Hypersensitivity pneumonitis

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18
Q

What is sarcoidosis?

A

A multisystem granulomatous disorder of unknown aetiology

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19
Q

What is the histopathology of sarcoidosis?

A
  • Epithelioid and giant cell granulomas
  • Necrosis/caseation very unusual
  • Little lymphoid infiltrate
  • Variable associated fibrosis
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20
Q

Who is commonly affected by sarcoidosis?

A
  • Young adults

- Females more than males

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21
Q

Where are the most common sites of sarcoidosis?

A
  • Inter-thoracic lymph nodes

- Lungs

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22
Q

How does sarcoidosis usually present in a young adult?

A
  • Acute arthralgia
  • Erythema nodosum
  • Bilateral hilar lymphadenopathy
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23
Q

How is sarcoidosis diagnosed in a patient who is asymptomatic?

A

Incidental abnormal chest X-ray

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24
Q

How might sarcoidosis present?

A
  • Shortness of breath
  • Cough
  • Abnormal chest X-ray
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25
Q

How is sarcoidosis normally diagnosed?

A
  • Based on clinical findings
  • Image findings
  • Serum Ca+ and ACE
  • Biopsy
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26
Q

What is hypersensitivity pneumonitis?

A

Group of immunologically mediated lung diseases in which a hypersensitivity response occurs in a sensitised individual to an inhaled antigen.

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27
Q

What antigens can cause hypersensitivity pneumonitis?

A
  • Thermophilic actinomycetes (micropolyspora faeni) (thermoactinomyces vulgaris)
  • Bird/animal proteins (faced, bloom)
  • Fungi (aspergillus spp)
  • Chemicals
  • Others
28
Q

What is the acute presentation for hypersensitivity pneumonitis?

A
  • Fever, dry cough, myalgia
  • Chills 4-9 hrs after Ag exposure
  • Crackles, tachyopnoea
  • Precipitating antibody
29
Q

What is the chronic presentation for hypersensitivity pneumonitis?

A
  • Insidious
  • Malaise, shortness of breath, cough
  • Low grade illness
  • Crackles and some wheeze
30
Q

What can hypersensitivity pneumonitis lead to?

A

Respiratory failure

31
Q

How is gas transfer affected in hypersensitivity pneumonitis?

A

Gas transfer is low

32
Q

What is the histopathology of hypersensitivity pneumonitis?

A

-Immune complex mediated type III and type IV hypersensitivity reaction
-Soft centriacinar epithelioid granulomata
-Interstitial pneumonitis
-Foamy histiocytes
-Bronchiolitis obliterans
Upper zone disease

33
Q

What are other names for Usual interstitial pneumonitis?

A
  • Cryptogenic fibrosing alveolitis

- Idiopathic pulmonary fibrosis

34
Q

What can cause UIP?

A

-Connective tissue diseases
-Drugs
-Asbestos
-Viruses
Most are cryptogenic or idiopathic

35
Q

What are the main connective tissue diseases in which UIP is seen?

A
  • Scleroderma

- Rheumatoid disease

36
Q

What is the histopathology of UIP?

A
  • Patchy interstitial chronic inflammation
  • Type II pneumocyte hyperplasia
  • Smooth muscle and vascular proliferation
  • Evidence of old and recent injury
  • Proliferating fibroblastic foci
37
Q

What can be seen in UIP in the histopathology in terms of evidence of old and recent injury?

A
  • Temporal heterogeneity

- Spatial heterogeneity

38
Q

Who is usually affected by idiopathic pulmonary fibrosis (UIP)?

A
  • Elderly

- Males more than females

39
Q

What is usually the pathology of idiopathic pulmonary fibrosis?

A

Usual interstitial pneumonitis

40
Q

What are the symptoms and signs of idiopathic pulmonary fibrosis?

A
  • Dyspnoea
  • Cough
  • Basal crackles
  • Cyanosis
  • Clubbing
41
Q

What is the prognosis of idiopathic pulmonary fibrosis?

A
  • Progressive disease
  • Most dead within 5 years
  • Some fulminant
  • Some steroid responsiveness
42
Q

What can be seen on the chest X-ray of a patient with idiopathic pulmonary fibrosis?

A
  • Basal/posterior
  • Diffuse infiltrates
  • Cysts
  • ‘Ground glass’
43
Q

How is gas transfer affected by idiopathic pulmonary fibrosis?

A

Reduced gas transfer

44
Q

What are other pattern responses?

A
  • Non-specific interstitial pneumonia (NSIP)
  • Asbestos
  • Silicosis
  • Bronchiolitis obliterans organising pneumonia (BOOP)
  • Cryptogenic organising pneumonia (COP)
45
Q

What is airflow in airways dependent on?

A

Pressure differences

46
Q

How saturated is the blood leaving the capillary bed if the FIO2 is 0.21?

A

98%

47
Q

How soluble is CO2?

A

Very soluble and rapidly equilibrates between blood and air

48
Q

What are the normal values for PaCo2?

A

4.8-6.0kPa

49
Q

What are the normal values for PaO2?

A

10.5-13.5kPa

50
Q

What are the 2 kinds of respiratory failure?

A
  • Type I: PaO2<8kPa (PaCO2 normal or low)

- Type II: PaCo2>6.5kPa (PaO2 usually low)

51
Q

What are the 4 abnormal states associated with hypoxaemia?

A
  • Alveolar hypoventilation
  • Shunt
  • Ventilation/perfusion imbalance V/Q
  • Diffusion impairment
52
Q

Why does alveolar hypoventilation lead to hypoxaemia?

A
  • Hypoventilation increases PAO2 and thus increases PaCO2

- Increase in PACO2 decreases PAO2, which causes PaO2 to fall

53
Q

How is the fall in PaO2 due to hypoventilation corrected?

A

Raising FIO2

54
Q

What is the commonest cause of hypoxaemia?

A

Low V/Q

55
Q

Why does low V/Q arise in some alveoli?

A

Due to local alveolar hypoventilation due to some focal disease

56
Q

What does hypoxaemia due to low V/Q respond to?

A

Responds well to even a small increases in FIO2

57
Q

What does gas flow through a membrane depend on?

A
  • Thickness of membranes
  • Surface area of membranes
  • Gas pressure across membranes
58
Q

How does the diffusion of CO2 differ to that of O2?

A

It diffuses 20 times faster due to its greater solubility

59
Q

What do diseases impairing gas diffusion usually not do?

A

Change the CO2 levels

60
Q

What does diffusion impairment do?

A

Mean it takes longer for blood and alveolar air to equilibrate, particularly for oxygen

61
Q

How long does equilibration normally take?

A

0.25 seconds

62
Q

How long does capillary transit usually take?

A

0.75 seconds

63
Q

Why may hypoxaemia be corrected by increasing FIO2?

A
  • This increases PAO2

- Increase in rate of diffusion

64
Q

How does the time to equilibrate differ in disease states?

A
  • May take closer to 0.75 seconds
  • PaO2 maintained at rest
  • Serious falls in PaO2 on exercise
65
Q

What is shunt?

A

Blood passing from right to left side of heart without contacting ventilated alveoli

66
Q

When does pathological shunt occur?

A
  • AV malformations
  • Congenital heart disease
  • Pulmonary disease
67
Q

What do large shunts respond poorly to?

A

Increases in FIO2