Lung function tests with disease

Question 1

What does FEV1 stand for?

Answer 1

Forced expiratory volume 1 second

Question 2

What is meant by FEV1?

Answer 2

The volume of air expired in the first second of a forced expiration

Question 3

What does FVC stand for?

Answer 3

Forced vital capacity

Question 4

What is meant by FVC?

Answer 4

Same as vital capacity - after maximum forced inspiration, the maximum volume of air that can be forcefully expired from the lungs

Question 5

What is normal FEV1/FVC?

Answer 5

0.7

Question 6

How does obstructive disease affect the lungs themselves?

Answer 6

Airway narrowing

Question 7

How does obstructive disease affect inspiration?

Answer 7

It doesn’t, inspiration is normal

Question 8

How does obstructive disease affect expiration?

Answer 8

Reduced expiration

Question 9

Why does obstructive disease reduce expiration?

Answer 9

Airways narrow and collapse sooner

increased resistance to air flow out of airways

Question 10

How does obstructive disease affect FEV1?

Answer 10

Decreases

Question 11

How does obstructive disease affect FVC?

Answer 11

It doesn’t, FVC is normal

Question 12

Why is FVC normal with obstructive disease?

Answer 12

Can still inspire same volume of air

and expire same volume of air, just takes more time and effort to overcome the increased resistance to air flow

Question 13

How does obstructive disease affect FEV1/FVC?

Answer 13

Decreases to below 0.7

because smaller FEV1, but same FVC

Question 14

How does restrictive disease affect the lungs themselves?

Answer 14

Reduced lung compliance

Question 15

How does restrictive disease affect inspiration?

Answer 15

Reduced inspiration

Question 16

Why does restrictive disease reduce inspiration?

Answer 16

Change in pleural pressure doesn’t increase lung volume as much

Question 17

How does restrictive disease affect expiration?

Answer 17

Reduced expiration

Question 18

Why does restrictive disease reduce expiration?

Answer 18

Because inspiration is reduced

so expiration will be reduced as a consequence

Question 19

How does restrictive disease affect FEV1?

Answer 19

It doesn’t, normal for first second

Question 20

How does restrictive disease affect FVC?

Answer 20

Decreases

Question 21

Why does restrictive disease decrease FVC?

Answer 21

Because maximum inspiration is reduced

so maximum expiration will be reduced as a consequence

Question 22

How does restrictive diseas eaffect FEV1/FVC?

Answer 22

Increases to above 0.7

Because FEV1 is normal, but FVC is smaller

Question 23

What are the axes of a time-volume graph?

Answer 23

y axis - volume of air expired after maximum inspiration

x axis - time

Question 24

What shape is a time-volume graph? Why?

Answer 24

Rectangular hyperbola

As have expired more air, airways narrow
increases resistance to air flow out of lungs
hence expire less air

Question 25

What is FVC on a time-volume graph?

Answer 25

The peak of the graph | because it is maximum volume of air expired after maximum inspiration

Question 26

How does obstructive disease affect the time-volume graph?

Answer 26

Flatter gradient along the entire graph, showing lower FEV1 Eventually reaches its peak, which is at the same level as the normal graph, showing it has same FVC

Question 27

How does restrictive disease affect the time-volume graph?

Answer 27

Same initial gradient as the normal graph, showing same FEV1 But reaches a lower peak compared to the normal graph, showing it has a lower FVC

Question 28

What are the axes of a flow-volume graph?

Answer 28

y axis - flow x axis - volume of air expired after maximum inspiration

Question 29

What is the shape of a flow-volume graph?

Answer 29

Rapid rise | followed by a slower fall

Question 30

Explain the shape of the flow-volume graph

Answer 30

Rapid rise then slower fall because | as have expired more air, airways narrow, increasing resistance in airways, reduced air flow out of airways

Question 31

What is the peak of the flow-volume graph?

Answer 31

Peak expiratory flow

Question 32

What is peak expiratory flow?

Answer 32

Maximum flow of air during expiration

Question 33

How does obstructive disease affect the flow-volume graph?

Answer 33

Lower peak expiratory flow The fall of the curve has a more "scooped" shape

Question 34

How does restrictive disease affect the flow-volume graph?

Answer 34

Lower peak expiratory flow The curve falls to a lower volume of air expired