Restrictive Lung Disorders Flashcards

1
Q

What is a restrictive lung disorder

A

A disorder which prevents normal expansion of the lungs.

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2
Q

What helps to keep the lung inflated

A

The negative pressure

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3
Q

What can be affected to bring about extra-pulmonary disease

A

The visceral pleura, the parietal pleura, the chest wall, the bones, the muscles or the nerves.

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4
Q

What can be affected to bring about intrapulmonary disease

A

The alveolar spaces.

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5
Q

What can happen to the nerves innervating the respiratory muscles to bring about restrictive disease

A

The integrity of respiratory nerves can be impaired. This could be due to a high cervical dislocation.

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6
Q

What can happen to neuromuscular junctions to bring about restrictive disease

A

These can be impaired such as in myasthenia gravis.

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7
Q

What is a disorder of the muscles that can cause restrictive disease

A

Muscular dystrophy.

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8
Q

What causes pleural thickening and therefore can be an extra-pulmonary cause of restrictive disease

A

Asbestos exposure.

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9
Q

What is an example of a skeletal abnormality that can cause restrictive disorder

A

Scoliosis.

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10
Q

What happens in intrapulmonary causes of restrictive lung disease

A

There is thickening or fibrosis in the interstitial space which impairs gas exchange and disrupts mechanics. There will be reduced elasticity and expansion.

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11
Q

What are 6 examples of intra-pulmonary restrictive disorders

A
  • Silicosis
  • Asbestosis
  • Drug-induced lung fibrosis
  • Pneumoconiosis
  • Rheumatoid lung
  • Bird fanciers lung
  • Idiopathic pulmonary fibrosis
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12
Q

What is the formula for the elastic recoil pressure

A

Elastic recoil pressure = alveolar pressure - pleural pressure.

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13
Q

What is pulmonary compliance

A

The ability of the lungs to stretch during a change in volume relative to an applied change in pressure.

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14
Q

What is the relationship between inflation pressure, compliance and elastic recoil

A

A lower compliance means a greater inflation pressure is required to inflate the alveoli. Increased inflation pressure increases the alveolar pressure which means the elastic recoil of the alveoli is increased (since elastic recoil is alveolar pressure - pleural pressure)

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15
Q

What is elastance

A

The change in pressure over the change in volume.

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16
Q

What makes alveoli more rigid and have decreased compliance

A

More fibrous tissue (as opposed to elastic tissue)

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17
Q

What does increased elastic recoil mean for the alveoli

A

They deflate easily.

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18
Q

Which disorder is associated with increased compliance

A

Emphysema in COPD.

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19
Q

What does increased compliance mean for the alveoli

A
  • There is less elastic tissue so the alveoli will be more floppy
  • The alveoli will inflate at low pressure
  • There will be decreased elastic recoil so the alveoli will be difficult to deflate.
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20
Q

What happens to the tissue in alveoli when there is increased compliance

A

It is less elastic so more floppy

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21
Q

What happens to the elastic recoil when there is increased compliance

A

There is decreased elastic recoil so alveoli are more difficult to deflate.

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22
Q

Why is knowing about compliance important

A

When deciding how much inflation pressure to apply when ventilating someone.

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23
Q

What causes surface tension in alveoli

A

The moisture of alveoli causes surface tension. Alveoli are all lined with a biofilm of moisture which exerts pressure to create surface tension.

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24
Q

Are all alveoli the same size

A

No, all alveoli are of different sizes.

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25
Q

What is Laplace’s law for a sphere

A

P = (2XsT)/radius where sT is surface tension.

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26
Q

What does the different sizes of alveoli mean for the alveolar pressure

A

Large alveoli have relatively low alveolar pressure while small alveoli have relatively high alveolar pressure.

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27
Q

What does the different alveolar pressures in different sized alveoli cause

A

Air moves from the high pressure areas to the low pressure areas so smaller alveoli empty into larger alveoli.

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28
Q

Why do alveoli with different pressures present a problem

A

This causes alveolar instability as alveoli are constantly trying to equilibrate, and can cause collapse.

29
Q

What is the molecule which equals out the pressure in different sized alveoli, therefore avoiding alveolar instability

A

Surfactant

30
Q

What is the role of surfactant

A

To reduce surface tension

31
Q

Which types of cells produce surfactant

A

Alveolar type 2 cells

32
Q

What is surfactant composed of

A

Lipids (90%) of which are mainly phospholipids and proteins (10%).

33
Q

If surfactant hydrophobic or hydrophilic

A

Surfactant has a hydrophobic end and a hydrophilic end. The hydrophobic end is in a gas state while the hydrophilic end is in a fluid state.

34
Q

What is the hydrophobic and gaseous part of the surfactant molecule composed of

A

Fatty acids

35
Q

What is the hydrophilic and fluid part of the surfactant molecule composed of

A

Glycerol, phosphate and choline.

36
Q

What molecules separate surfactant molecules

A

Water molecules

37
Q

Are there more water molecules between surfactant molecules upon inspiration or expiration

A

Inspiration when the lung is expanded.

38
Q

How are surfactant molecules spaced out in a deflated alveolus

A

In a deflated alveolus, water molecules are exuded surfactant molecules are close to one another.

39
Q

How is a change in surface tension exerted by surfactant molecules in a deflated alveolus

A

In a deflated alveolus the surfactant molecules are close to one another as water is exuded. The hydrophilic ends interact with one another and exert a change in surface tension.

40
Q

How is surface tension in alveoli decreased

A

When surfactant molecules are close to one another and water exuded

41
Q

How is surface tension in alveoli increased

A

When surfactant molecules are spread out and there are more water molecules.

42
Q

What happens to surface tension in alveoli with a small radius

A

The surfactant molecules are close together and the surface tension is decreased. This is accompanied by lower pressure in the alveoli.

43
Q

What happens to surface tension in alveoli with a large radius

A

The surfactant molecules are spread out evenly and there are more water molecules. Surface tension is not changed or is increased.

44
Q

How does surfactant work to solve the pressure difference in different sized alveoli

A

Surfactant decreases the surface tension and therefore pressure in small alveoli, to make the pressure in different sized alveoli more similar and therefore to create less of a gradient.

45
Q

What is the cause of respiratory distress syndrome of the new-born (IRDS)

A

A lack of surfactant.

46
Q

At what stage in gestation does surfactant begin to be produced

A

30 weeks

47
Q

What does IRDS lead to

A
  • Low compliance
  • High inflation pressure
  • Rapid shallow breathing and fatigue
  • Hypoxaemia
48
Q

What type of surfactant deficiency is IRDS

A

Primary

49
Q

Which respiratory diseases have surfactant changes been found in

A
  • Acute respiratory distress syndrome (ARDS)
  • Pneumonia
  • Idiopathic pulmonary fibrosis
  • Lung transplant.
50
Q

What type of surfactant deficiencies often are those found in adulthood

A

Secondary

51
Q

What happens to the FEV1 in restrictive disorders

A

It is decreased

52
Q

What happens to FVC in restrictive disorders

A

It is decreased

53
Q

What happens to FEV1/FVC ratio in restrictive disorders

A

It is the same (as both FEV1 and FVC have decreased) or is increased.

54
Q

What happens to TLC in restrictive lung disorders

A

It is decreased.

55
Q

What is used for the measurement of functional residual capacity and why

A

Helium as it is not taken up by the blood at all

56
Q

What is used for the measurement of transfer factor

A

Carbon monoxide - a very small amount as you assume that CO should all be taken up by haemoglobin in the blood. If it is not this indicates a problem - possible V/Q mismatching.

57
Q

What are the predicted values of normal for lung volumes based upon

A
  • Age
  • Height
  • Gender
  • Ethnic Origin.
58
Q

What happens to the normal FEV1 with age

A

FEV1 increases at a young age and then after the age of around 40 decreases.

59
Q

What is the impact of smoking on the rate of decline of lung function

A

Smoking increases the rate in decline of lung function. The decline in lung function starts earlier and happens quicker in smokers.

60
Q

What happens to lung function when smokers quit smoking

A

Smokers never regain the capacity their lungs once had but the rate of decline in FEV1 slows again and becomes the same as a non-smoker.

61
Q

What are lung function tests used to distinguish between

A

Obstructive and restrictive disorders and also extra-and intrapulmonary restriction.

62
Q

What measurement is used to distinguish between extra- and intra-pulmonary restrictive lung diseases

A

Gas transfer

63
Q

Which two things does gas transfer measurement for distinguishing between intra- and extra-pulmonary restriction require

A

Measurement of gas exchange and alveolar volume.

64
Q

Which gas is ideal for measuring gas exchange

A

Carbon monoxide

65
Q

Why is carbon monoxide ideal for measuring gas exchange

A

Because it is rapidly taken up by haemoglobin with high affinity. It is non-toxic in small quantities, not produced by the body and is easy to measure.

66
Q

What is the ideal gas for measuring alveolar volume

A

Helium

67
Q

Why is helium the ideal gas for measuring alveolar volume

A

Because it is not taken up by haemoglobin. It is non-toxic, not produced by the body and easy to measure.

68
Q

What two quantities can carbon monoxide gas transfer measurement help to calculate

A
  • Total gas exchange capacity (TLCO)

- Efficiency of gas transfer per unit of the lung (KCO)