Pulmonary function testing

Question 1

Effort dependent tests

Answer 1

FEV/flow rates - spirometry

Question 2

Effort independent tests

Answer 2

Relaxed vital capacity - spirometry, helium/Nw washout static lung volumes, impulse oscillometry, exhaled breath nitric oxide

Question 3

Gas diffusion tests

Answer 3

CO transfer factor, arterial blood gases, SaO2 during exercise

Question 4

Flow volume curve pattern in obstructive disease

Answer 4

Reduced peak flow, scooped out midcurve

Question 5

Flow volume curve pattern in severe obstructive disease

Answer 5

Steeple pattern - reduced peak flow, rapid fall off

Question 6

Flow volume curve pattern in restrictive disease

Answer 6

Normal shape, normal peak flow, reduced volume

Question 7

What are the results of the following in obstructive and restrictive disease:

• PEFR
• FEV1
• FVC
• FEV1/FVC ratio
• FEV1 response to beta-2-agonist

Answer 7

• PEFR - obstructive = ↓, restrictive = normal
• FEV1 - obstructive = ↓, restrictive = ↓
• FVC - obstructive = normal in asthma, ↓ COPD, restrictive = ↓
• FEV1/FVC ratio - obstructive = <75%, restrictive = >75%
• FEV1 response to beta-2-agonist - obstructive = >15% in asthma, <15% in COPD, restrictive = no response

Question 8

Bronchial challenge testing

Answer 8

• Exercise
• Methacholine/histamine/mannitol - marker of airway hyper-responsiveness, concentration to produce 20% ↓ FEV1
• Allergens/chemicals - early and late responses, diagnosis of occupational asthma

Question 9

Exercise testing:

• FEV1 and PEF post exercise in asthma
• SaO2 during exercise in interstitial lung disease

Answer 9

• ↓ FEV1 or ↓ PEF in asthma

- ↓ SaO2 in ILD

Question 10

Full cardiopulmonary exercise test:

• What does it do?
• What does it measure?

Answer 10

• Differentiates cardiac vs respiratory dyspnoea

- Measures heart rate vs oxygen rate vs ventilatory rate

Question 11

Diffusing capacity for carbon monoxide (DLCO):

• What is it?
• In what conditions is it decreased?

Answer 11

• Total lung transfer for carbon monoxide

- Anaemia, emphysema, interstitial lung disease, pulmonary oedema, pulmonary emboli

Question 12

What is used to measure airway resistance?

Answer 12

Whole body plethysmography or impulse oscillometry

Question 13

Why is exhaled breath nitric oxide not useful in COPD?

Answer 13

Nitric oxide is suppressed by smoking