Lung Function Testing

Question 1

What is considered a normal approx. value for male forced vital capacity (FVC)?

Answer 1

4.8 L

Question 2

What is considered a normal approx. value for female forced vital capacity (FVC)?

Answer 2

3.7 L

Question 3

What is considered a normal approx. value for male Tidal Volume (Vt)?

Answer 3

500 mL

Question 4

What is considered a normal approx. value for female Tidal Volume (Vt)?

Answer 4

390 mL

Question 5

What is considered a normal approx. value for male Total Lung Capacity (TLC)?

Answer 5

6.0 L

Question 6

What is considered a normal approx. value for female Total Lung Capacity (TLC)?

Answer 6

4.7 L

Question 7

Forced Expiratory Volume in 1 second (FEV1).

Answer 7

The volume of air that the patient is able to exhale in the 1st second of forced expiration, starting from full inspiration.

Question 8

Forced Vital Capacity (FVC) (& what is it measured in?).

Answer 8

• The total volume of air that the patient can forcibly exhale in 1 breath, after full inspiration
• Measured in litres

Question 9

What is the FEV1/FVC ratio?

Answer 9

The ratio of FEV1 to FVC expressed as %

• FEV1 is 70%-80% of FVC in normal subjects (0.7-0.8)
• Excellent measure of airway limitation and allows differentiation obstructive from restrictive disease
• Standard diagnostic test for COPD
• Moderate airflow obstruction 0.5-0.6 (50-60%)
• Severe airflow obstruction 0.3 (30%)
• Restrictive disease 1.0

Question 10

What happens to the FEV1/FVC ratio when the patient has a restrictive disease?

Answer 10

• Both FEV1 and FVC are reduced (in proportion)
• FEV1:FVC ratio is normal or increased (>80%)

Question 11

What happens to the FEV1/FVC ratio when the patient has a obstructive disease?

Answer 11

• High intrathoracic pressures (generated by forced expiration) cause premature closure of the airways with trapping of air in the chest
• FEV1 is reduced
• FEV1:FVC ratio is reduced (<80%)

Question 12

What is Inspiratory Capacity made up of?

Answer 12

• Inspiratory Reserve Volume
• Tidal Volume

Question 13

What is Functional Residual Capacity made up of?

Answer 13

• Expiratory Reserve Volume
• Residual Volume

Question 14

What is Vital Capacity made up of?

Answer 14

• Inspiratory Reserve Volume
• Tidal Volume
• Expiratory Reserve Volume

Question 15

What is Total Lung Capacity made up of?

Answer 15

• Inspiratory Reserve Volume
• Tidal Volume
• Expiratory Reserve Volume
• Residual Volume