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CR 2 > Resp. function tests > Flashcards

Resp. function tests Flashcards

1
Q

What limitations/ problems may arise when completing respiratory function tests

A
  • Need to understand orders
  • Max effort
  • Mouthpiece leak
  • Ability to carry out orders
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2
Q

What is normal resp rate

A

<25

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3
Q

What is plotted in spirometry

A

Volume/ time

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4
Q

What is the FEV1/ VC if there is an obstructive defect

A

<75%

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5
Q

What is an obstructive defect typical in

A

Asthma, COPD, upper airway obstructions

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6
Q

What is the FEV1/ VC ratio in a restrictive defect

A

> 75%

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7
Q

What is restrictive defect typical in

A

Lung fibrosis, reduced chest wall movement and muscle disease

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8
Q

When is peak flow typically reduced

A

Large airway obstruction
Upper airway obstruction
Asthma

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9
Q

What diseases effect peak flow less

A

COPD

Small airway disease

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10
Q

When is peak flow lowest

A

Morning

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11
Q

What pattern is seen on peak flow charts with asthma

A

Saw tooth pattern

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12
Q

What changes in peak flow must be observed with asthma to determine diagnosis

A
  • > 20% dirunal variation for 3 days a week for 2 weeks
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13
Q

With what kind of training may peak flow increase

A

Inspiratory muscle training

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14
Q

What changes in FEV1 must be seen after use of bronchodilators to determine obsuctive disease is reversible

A

Increase by >15% or 200ml

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15
Q

A 15% increase in FEV1 is adequate to suggest reversibility after….

A

a) 400mg salbutamol via spacer
b) 2.5mg by nebuliser
c) 30mg/day of steroids for 14 days

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16
Q

What may be the problem if there is reduced inspiratory limb flow with normal expiratory flow

A

Extra-thoracic obsutrction

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17
Q

What may be the problem if there is reduction in both inspiratory and expiratory flow

A

Intra-thoracic obsutrction such as a goitre

18
Q

How do you measure vital capacity

A

Spirometry

19
Q

How can you measure total lung capacity

A
  • Inspiration of gas mixture including helium
  • Rebreathing
  • Dilution of helium and decrease in concentration * vital capacity= TLC
20
Q

Where do oxygen and co2 diffuse

A

Oxygen diffuses into circulation

CO2 diffuses out of the lungs

21
Q

How can you calculate alveolar volume and gas transfer

A
  • Single large breath of air with CO and helium

- Calculate total CO transfer and per l of lung volume

22
Q

What does TLCO stand for and how do you calculate it

A

Transfer factor for CO

=kco*va

23
Q

What can cause decreased TLCO (4)

A
  • Anaemia
  • Decreased perfusion
  • Decreased ventilation
  • V/Q mismatch
24
Q

What can cause increased TLCO (3)

A

Increased CO
Polycythaemia
Alveolar haemorrhage

25
Q

Describe the Fick principle

A

Volume of gas per unit time which diffuses across a tissue sheet is

a) proportional to sheet area
b) inversely proportional to thickness
c) proportional to difference in pressure on either side
d) dependent of permeability coefficient for gas

26
Q

What equation can be derived from the Fick principle

A

= area/thickness * pressure * diffusion constant

27
Q

What does diffusion constant depend upon

A

Solubility and molecular weight of gas

28
Q

What is Grahams law

A

Rate of diffusion of a gas is inversely proportional to square root of molecular weight

29
Q

What are the real life causes of reduced surface area causing reduced gas transfer

A

Pneumonectomy, lobectomy or reduced ventilation from obsutrction
Reduced effective area with emphysaemia or increased dead space

30
Q

What are the real life causes of increased membrane thickness

A

Pulmonary fibrosis
Alveolar proteinosis
Acute lung injury

31
Q

What are the real life causes of reduced oxygen concentration

A

High altitude

32
Q

Define airway resistance

A

Pressure difference between alveolae and the mouth

33
Q

How can airway resistance be measured

A

Body plethysmograph

Direct measurment of intrathoracic oesophageal pressures

34
Q

What is lung compliance defined as

A

Volume change per unit of pressure

35
Q

What does lung compliance depend upon

A

Alveolar surface tension and distensibility of lung tissue

36
Q

When is lung compliance increased/ decreased

A

Increased: emphysaema
Decreased: Lung fibrosis

37
Q

What is the effect of thorax deformities on chest wall compliance

A

Compliance is reduced

38
Q

Where is perfusion and ventilation highest

A

At the base

39
Q

How does pneumonia lead to hypoxia

A

Reduced ventilation

Increased perfusion

40
Q

What does anaerobic threshold correlate with

A

Cardiopulmonary capacity

Operative risk

41
Q

What is the effect of muscle wasting in COPD

A

Reduces maximum inspiratory muscles

Problems with mitochondrial dysfunction

CR 2 (33 decks)

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