Lung Function Testing

Question 1

Why might lung function tests be conducted?

Answer 1

Evaluation of the breathless patient
Screening for COPD or occupational lung disease
Lung cancer to assess fitness for treatment
Pre-operative assessment
Disease progression and treatment response
Monitoring of drug treatment which is toxic to the lungs
Pulmonary complications of systemic disease

Question 2

Peak flow, oximetry and spirometry can be conducted at the GP surgery. What other lung function tests can be conducted in a specialist setting?

Answer 2

Transfer factor
Lung volumes
Blood gases
Bronchial provocation testing
Respiratory muscle function
Exercise testing

Question 3

What instructions should be given to a patient when doing a spirometry test?

Answer 3

Take a big breath in as far as you can, blow out as far as you can for as long as possible, then take a big breath all the way in

Question 4

What are the disadvantages of spirometry testing?

Answer 4

Requires an appropriately trained technician
Effort and technique dependent
May not be possible if pain is too frail or is in too much pain

Question 5

What is the normal FEV1/FVC?

Answer 5

> 70%

Question 6

How are predicted % FEV1 and FVC values determined?

Answer 6

These are based on age, gender, race, height and atmospheric values

Question 7

What conditions are classified as obstructive lung disease?

Answer 7

COPD and asthma

Question 8

How is obstructive lung disease indicated on spirometry?

Answer 8

<70% FEV1/FVC

Question 9

What pattern is seen on a flow/volume loop in COPD?

Answer 9

Church and steeple pattern

Question 10

What reversibility criteria on spirometry define asthma?

Answer 10

An increase of 15% AND 400ml reversibility in FEV1

Question 11

What signs are seen on spirometry for restrictive lung disease?

Answer 11

Proportionally reduced FEV1 and FVC

FEV1/FVC >70%

Question 12

What are the possible causes of restrictive spirometry?

Answer 12

Interstitial lung disease
Kyphoscoliosis/chest wall abnormality
Previous pneumonectomy
Neuromuscular disease
Obesity
Poor effort/technique

Question 13

What is the transfer factor test of lung function?

Answer 13

The test involves a single breath of a very small concentration of carbon monoxide. CO has a very high affinity to haemoglobin. The concentration of CO in expired gas can be used to derive the uptake in the lungs

Question 14

When would the transfer factor test be reduced?

Answer 14

Emphysema
Interstitial lung disease
Pulmonary vascular disease
Anaemia

Question 15

What lung volume can be tested on a lung volume test that spirometry cannot detect?

Answer 15

Residual volume

Question 16

What is measured in a helium dilution lung volume test?

Answer 16

Measures the inspiration of a known quality of inert gas

Question 17

When are lung volumes reduced?

Answer 17

Restrictive lung disease

Question 18

How is reserved volume affected in obstructive lung disease?

Answer 18

Increased reserved volume

Question 19

What is an oximetry test?

Answer 19

A non-invasive measurement of saturation of haemoglobin by oxygen

Question 20

What is measured in an oximetry?

Answer 20

Oxyhaemoglobin and deoxyhaemoglobin are detected as they absorb infrared light differently.

Question 21

Why can oximetry not measure ventilation?

Answer 21

It doesn’t measure carbon dioxide

Question 22

What are the main causes of hypoxaemia?

Answer 22

Hypoventilation e.g. drugs, neuromuscular disease
Ventilation/perfusion mismatch e.g. COPD, pneumonia
Shunt e.g. congenital heart disease
Low inspired oxygen e.g. altitude, flight

Question 23

Ventilation perfusion mismatch will fully correct with oxygen administration. T/F?

Answer 23

False - it will not fully correct

Question 24

What test can be used to measure arterial partial pressure of oxygen directly?

Answer 24

Arterial blood gases