Pulmonary: Lung Volumes and Capacities

Question 1

The volume of air that occupies the non-respiratory conducting airways.

Answer 1

Anatomic dead space volume (VD)

Question 2

The maximal volume of air that can be exhaled after a normal tidal exhalation

Answer 2

Expiratory reserve volume (ERV)

ERV is approximately 15% of total lung volume.

Question 3

The maximal volume of air exhaled in a specified period of time: usually the 1st, 2nd, and 3rd second of a forced vital capacity maneuver

Answer 3

Forced expiratory volume (FEV₁)

• Reflects airflow in large (& medium sized) airways
• 75% of FVC should be exhaled in the first second

Question 4

The volume of air in the lungs after normal exhalation

Answer 4

Functional residual capacity (FRC)

FRC = ERV + RV. FRC is approximately 40% of total lung volume.

Question 5

The maximal volume of air that can be inspired after a normal tidal exhalation.

Answer 5

Inspiratory capacity (IC)

IC = TV + IRV. IC is approximately 60% of total lung volume.

Question 6

The maximal volume of air that can be inspired after normal tidal volume inspiration:

Answer 6

Inspiratory reserve volume (IRV)

IRV is approximately 50% of total lung volume.

Question 7

The maximum flow of air during the beginning of a forced expiratory maneuver:

Answer 7

Peak expiratory flow (PEF)

Question 8

The volume of gas remaining in the lungs at the end of a maximal expiration.

Answer 8

Residual volume (RV)

RV is approximately 25% of total lung volume

Question 9

Total volume inspired and expired with each breath during quiet breathing

Answer 9

Tidal volume (TV)

TV is approximately 10% of total lung volume

Question 10

The volume of air in the lungs after a maximal inspiration

Answer 10

Total lung capacity (TLC)

the sum of all lung volumes. TLC = RV + VC or TLC = FRC + IC.

Question 11

The volume change that occurs between maximal inspiration and maximal expiration

Answer 11

Vital capacity (VC)

VC = TV + IRV + ERV. VC is approximately 75% of total