Lung Volumes and Capacities

Question 1

Total lung capacity

Answer 1

Lung volumes, when summed, equal total lung
capacity or volume

Question 2

Residual volume

Answer 2

Cannot be measured with an office spirometer but must use whole body plethysmography or gas dilution

Question 3

Tidal volume

Answer 3

Tidal volume is the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied.

Question 4

Inspiratory Reserve Volume (IRV)

Answer 4

The maximal volume that can be inhaled from the end-inspiratory level

Question 5

Inspiratory capacity (IC)

Answer 5

The sum of IRV and TV

Question 6

Inspiratory vital capacity (IVC)

Answer 6

The maximum volume of air inhaled from the point of maximum expiration

Question 7

Vital capacity (VC)

Answer 7

– Sum of tidal volume, inspiratory reserve volume and expiratory reserve volume

– If measured by rapid forced expiration from peak inspiration then called forced vital capacity

Question 8

Forced Expiratory Volume

Answer 8

• The rate at which air can be blown out of the
lungs in an exertional effort from peak inspiration
indicates the resistance to airflow and
compliance of the lungs/thoracic cavity

• Measuring the amount (FEV1) or percent
(FEV1/FVC) of the FVC that can be blown out in 1
second, therefore, is used as an indicator of how
much resistance to flow is present and also the
compliance of the lungs/thoracic cavity

Question 9

Forced vital capacity (FVC)

Answer 9

The determination of the vital capacity from a maximally forced expiratory effort.

Question 10

FEV1

Answer 10

Volume that has been exhaled at the end of the first second of forced expiration.

Question 11

Expiratory reserve volume (ERV)

Answer 11

Is the additional air that can be forcibly exhaled after the expiration of a normal tidal volume.

Question 12

Total lung capacity (TLC)

Answer 12

Is the maximum amount of air that can fill the lungs (TLC = TV + IRV + ERV + RV).

Question 13

Vital capacity (VC)

Answer 13

Is the total amount of air that can be expired after fully inhaling (VC = TV + IRV + ERV = approximately 80 percent TLC). The value varies according to age and body size.

Question 14

Inspiratory Capacity (IC)

Answer 14

Is the maximum amount of air that can be inspired (IC = TV + IRV).

Question 15

Functional residual capacity (FRC)

Answer 15

Is the amount of air remaining in the lungs after a normal expiration (FRC = RV + ERV).