S6.1 Lung Function Testing

Question 1

Describe an obstructive airway pattern

Answer 1

Airways narrowed, lungs easy to fill but hard to expire.
Volume-time graph reaches normal height but slower
Flow-volume graph has a big curve

Question 2

Describe a restrictive airway pattern

Answer 2

Lungs difficult to fill.
Rate of rise of volume is initially normal, but you cannot blow out as much, so reduced vital capacity.
Volume-time graph is lower
Flow-volume graph is small showing reduced volume.

Question 3

What is FVC?

Answer 3

Forced vital capacity.

The maximum volume expired from full lungs, 5L.

Question 4

What is FEV1?

Answer 4

Forced expiratory volume.

The volume of air that is forcibly exhaled in one second.

Question 5

What is the FEV1/FVC ratio for an obstructive deficit?

Answer 5

<70% as FEV1 reduced

Eg asthma or COPD

Question 6

What is the FEV1/FVC ratio for a restrictive deficit?

Answer 6

> 70% as both FEV1 and FCV reduced

Eg pulmonary fibrosis