Lung function Testing

Question 1

What is a nebulizer?

Answer 1

This turns liquid medication into a fine mist so it is more easily delivered into the lungs

Question 2

What spirometry tests do you need to carry out?

Answer 2

1. Base-line spirometry- Investigates lung function where a diagnosis has not been made
2. Post bronchodilator spirometry- To diagnose obstructive conditions where baseline spirometry shows obstructive pattern
3. Reversibility testing- To differentiate between asthma and COPD (not usually required)

Question 3

What is the procedure for lung function testing?

Answer 3

1) check for active infection
2) Record age, ethnicity, gender and height which may affect results
3) Perform 3 vital capacity tests (results don’t vary by more than 100ml)
4) Perform 3 Forced vital capacity tests (results don’t vary by more than 100ml)
5) if baselines show obstructive pattern perform post-bronchodilator testing

Question 4

What is a BTPS conversion?

Answer 4

This something you must make in spirometry testing as the surrounding air is usually much cooler and dryer than air in the lungs so when it leaves the lungs, the air gets smaller so the result will appear 6-10% less than the actual volume of air in the lungs so you therefore need to account for this.

Machines usually make this conversion for you so you don’t have to worry about it.

Question 5

What is tidal volume?

Answer 5

This is just regular breathing in and out

Question 6

What is the vital capacity?

Answer 6

This is the biggest inhalation and exhalation volume that you can do.

Question 7

What is residual volume?

Answer 7

This is the volume of air that remains in the lungs

Question 8

What is FVC?

Answer 8

Forced vital capacity- total amount of air that you can forcibly blow out after full inspiration, measured in litres

Question 9

What is FEV1?

Answer 9

The total amount of air that you can forcibly blow out in one second, measured in litres

Question 10

What is a healthy FEV1/FVC ratio?

Answer 10

Around 80%

Question 11

What is PEF?

Answer 11

Peak Expiratory Flow- the speed of the air moving out of your lungs at the start of expiration (useful when working with asthma patients)

Question 12

Describe an obstructive pattern?

Answer 12

This is where the FEV1 is significantly lower as the patient struggles to get air out quickly. But if they have enough time the overall vital capacity is quite similar.

Question 13

Describe a restrictive pattern?

Answer 13

This is as a result of less alveoli taking place in gas exchange so there is just less air moving in and out. This results in a lower FEV1 and FVC. The actual slope of the line is similar though, the volumes are just lower. FEV1:FVC ratio remains similar.

Question 14

What is meant by a reversible ventilatory obstruction?

Answer 14

This is asthma. Prior to giving a patient a bronchodilator, there is narrowing of the bronchial airways which results in the FEV1 and FVC being lower. However, when you give a patient a bronchodilator, these values increase to more normal rates. This is different to patients with COPD.