3.2 Tests of lung function

Question 1

What is spirometry?

Answer 1

Patient breaths into a closed chamber where the volume will change with ventilation.

Question 2

What is tidal volume?

Answer 2

Volume in and out with each breath (0.5L)

Question 3

What is inspiratory reserve volume?

Answer 3

Extra volume that can be breathed in over that at rest (2.5L)

Question 4

What is expiratory reserve volume?

Answer 4

Extra volume that can be breathed out over that at rest (1.5L)

Question 5

What is residual volume?

Answer 5

Volume remaining after maximal expiration (0.8L)

Question 6

What is vital capacity?

Answer 6

Max inspiration to max expiration (5L)

Question 7

What is inspiratory capacity?

Answer 7

Largest breath in (3L)

Question 8

What is the functional residual capacity?

Answer 8

Air left in lungs at the resting expiratory level (2L)

Question 9

What is the total lung capacity?

Answer 9

Volume of gas in the lungs at the end of maximal inspiration. (5.8L)

Question 10

What factors may influence vital capacity?

Answer 10

Compliance of lungs
Force of inspiratory muscles
Airway resistance

Question 11

When comparing to a standard, what factors is the standard based on?

Answer 11

Age, sex, height

Question 12

What is single breath spirometry?

Answer 12

Patient fills their lungs and breathes out as much as possible. How fast and how much air is breathed out is measured.

Question 13

What is the forced vital capacity (FVC)?

Answer 13

Maximal volume expired from full lungs (5L)

Question 14

What is the FEV1?

Answer 14

Volume expired in the first second of breathing out. Should be more than 70% of FVC?

Question 15

How are spirometry results shown?

Answer 15

Vitalograph

Question 16

If the airways are narrowed how will FVC and FEV1 change?

Answer 16

FVC will remain the same

FEV1 will decease

Question 17

If the lungs are restricted, how will FVC and FEV1 change?

Answer 17

FVC will decrease

FEV1 will remain the same

Question 18

What is the PEFR?

Answer 18

Peak Expiratory Flow Rate

Shown on a graph as a loop showing flow rate against volume. When the lungs are full, flow rate will be at a maximum

Question 19

What is a helium dilution test?

Answer 19

Breathe in a known volume of helium. Helium concentration will get diluted and show the volume of the chest

Question 20

What is a nitrogen washout test?

Answer 20

1 breath of pure O2 is breathed and the N2 is measured

The transition point to a mixture of O2 and N2 is measured to show serial dead space.