Lung Function Tests and Common Lung Conditions

Question 1

What is an obstructive lung disease?

Answer 1

Obstruction of air flow especially on expiration

Question 2

What is a restrictive lung disease?

Answer 2

Restriction of lung expansion

Question 3

What two diseases come under Chronic Obstructive Pulmonary Disorder?

Answer 3

Chronic bronchitis and emphysema.

Question 4

What is chronic bronchitis?

Answer 4

Inflammation of the bronchi

Question 5

What 3 condtions come under obstrcutive lung disorders?

Answer 5

Asthma, Chronic bronchitis and emphysema

Question 6

Do obstrcutive lung disorders affect inspiration or expiration?

Answer 6

Expiration

Question 7

What does idiopathic mean?

Answer 7

The cause of the disease is uknown.

Question 8

What are the four restrcitive lung disorders?

Answer 8

Fibrosis, Infant Respiratory distress syndrome, oedema and pneumothorax.

Question 9

What is spirometry?

Answer 9

It is a technique commonly used to measure lung function.

Question 10

How can the measuremnts of spirometry be classed?

Answer 10

Static or dynamic

Question 11

What does a static test mean in spirometry?

Answer 11

The only volume measred is the volume exhaled or inhaled.

Question 12

What does a dynamic test mean in spirometry mean?

Answer 12

The time taken to exhale a certain volume.

Question 13

What can spirometry measure?

Answer 13

Inspiratory reserve volume, expiratory reserve volume, tidal volume, inspiratory capacity, vital capacity (anything that doesn’t have the residual volume included.)

Question 14

What is the forced expiratory volume in 1 second?

Answer 14

It is taking a deep breath and seeing what volume of air you can push out in 1 second.

Question 15

What is the forced vital capacity?

Answer 15

It is how much you can breath out over however long it takes.

Question 16

What is the normal FEV1:FVC ratio/percentage?

Answer 16

80%

Question 17

How does an obstructive disease affect spirometry?

Answer 17

Rate at which air is exhaled is slower, total expired volume (FVC) is also reduced, major effect is on airways and so FEV1 is reduced to a greater extent than FVC and so the ratio is reduced.

Question 18

How does a restrictive disease affect spirometry?

Answer 18

It decreases the FEV1 but this is only because there isn’t much air in the lungs anyway, but FVC is reduced because there isn’t much air in the lungs anyway. However they are both reduced but within proportion and so the ration is close to normal and even higher than normal. Absolute rate of airflow is reduced.

Question 19

How does compliance vary with inspiration?

Answer 19

Compliance is very low at the start of inspiration and then it increases greatly at the end of inspiration. For large chnages in intrapleural pressure at the start of inpiration we have a small chnage in volume. For small changes intrapleural pressure at the end of inspiration there is a large chnage in volume.

Question 20

How does compliance vary with expiration?

Answer 20

Compliance is low at the start of expiration, compliance increases towards the end of xpiration.

Question 21

Quick note

Answer 21

Inspiratory and expiratory curves are not superimosed onto each other, it requires a greater change in pressure to reach a particular lung volume during inspiration, than to maintain that volume during expiration.

Question 22

Why does inspiration require a greater change in pressure?

Answer 22

• Overcome lung inertia during inspiration

* Overcome surface tension during inspiration

Question 23

What is transpulmonary pressure?

Answer 23

The relationship between alveolar pressure and the intrapleural pressure (always positive).

Question 24

What is the average FEV1 for a healthy male?

Answer 24

4 litres

Question 25

What is the forced vital capacity for a healthy male?

Answer 25

5 litres

Question 26

What are the FEV and FVC for an obstructive respiratory disorder?

Answer 26

FEV decreases (significantly) FVC is also reduced FRC may be increased Ratio is reduced

Question 27

What are the FEV and FVC for an restrictive respiratory disorder?

Answer 27

Absolute rate of airflow is reduced (FEV redcued) Total volume is reduced due to limitations to lung expansion (FVC) Ratio remains constant or can increase as a large proportion of volume can be exhaled in the first second.