18 LUNG VOLUMES

Question 1

PULMONARY FUNCTION TESTING

Answer 1

Used to determine ability of lung to function.
Measures different aspects of lung function which helps to determine diagnosis, medication and other treatment.

Question 2

TIDAL VOLUME

Answer 2

The amount of air that passes in and out of the lungs on quiet respiration.
Normally is around 500 mL.

Question 3

INSPIRATORY CAPACITY

Answer 3

The maximum amount of air that can be inspired into the lungs after resting expiration.
Normally is around 3500 mL.

Question 4

INSPIRATORY RESERVE VOLUME

Answer 4

The amount of air a person can breathe in after a resting inspiration. (i.e. above the tidal volume)
Normally is around 3000 mL.

Question 5

EXPIRATORY RESERVE VOLUME

Answer 5

The amount of air that a person can exhale after a quiet expiration. (i.e. above the tidal volume expiration)
Normally is around 1000 mL.

Question 6

VITAL CAPACITY

Answer 6

The maximum volume of air that can be expelled from the lungs following the deepest possible inspiration.
It is determined by the strength of the respiratory muscles and the resistance of the thoracic cage and lungs to expand and contract.
The normal levels are as follows:
average male = 4.5 liters
average female = 3.2 liters

Question 7

RESIDUAL VOLUME

Answer 7

The air that cannot be expired after forceful expiration.
Normally is about 1500 mL.

Question 8

FUNCTIONAL RESIDUAL VOLUMES

Answer 8

The amount of air that remains in the lungs at the end of quiet expiration, at the resting respiratory level.
Normally about 2500 mL.

Question 9

FORCED EXPIRATORY VOLUME

Answer 9

It is usual to measure the vital capacity of the lungs with a spirometer, to give some indication of the condition of the lungs. This is most often used with a dry, waterless spirometer called a vitalograph.

Question 10

MAXIMAL VENTILATION VOLUME

Answer 10

The subject is asked to breathe as deeply and rapidly as possible for 15 seconds and the ventilation per minute is then calculated. Normally, it is greater than 100 liters per minute.

Question 11

PEAK FLOW

Answer 11

In this the patient’s highest expiratory flow rate during forced expiration is measured and this is related to the FEV1 and MVV.

Question 12

THE RATE OF RESPIRATION

Answer 12

Normally this is 14 breathes per minute at rest.
12-20 generally considered normal for an adult

Question 13

ANATOMICAL DEAD SPACE

Answer 13

Normal tidal volume is 500 mL.
Only 350 mL reaches the alveoli.
The remaining 150 mL is still in the air passages at the end of inspiration and cannot take part in gaseous exchange.

Question 14

PHYSIOLOGICAL DEAD SPACE

Answer 14

Alveolar and anatomical dead space together.