Lung Volumes

Question 1

Inspiratory reserve volume

IRV

Answer 1

Air that can still be breathed in after normal inspiration

Question 2

Tidal volume

TV

Answer 2

Air that moves into lung with each quiet inspiration, typically *500 mL

Question 3

Expiratory reserve volume

ERV

Answer 3

Air that can still be breathed out after normal expiration

Question 4

Residual volume

RV

Answer 4

Air in lung after maximal expiration

*cannot be measured on spirometry

Question 5

Inspiratory capacity

IC

Answer 5

IRV + TV

Question 6

Functional residual capacity

FRC

Answer 6

RV + ERV

Volume of gas in lungs after normal expiration; includes RV

*cannot be measured on
spirometry

Question 7

Vital capacity

VC

Answer 7

TV + IRV + ERV

Maximum volume of gas that can be expired after a maximal inspiration

Question 8

Total lung capacity

TLC

Answer 8

IRV + TV + ERV + RV

Volume of gas present in lungs after a maximal
inspiration; includes RV

*cannot be measured by spirometry

Question 9

physiologic dead space

Answer 9

anatomic dead space of conducting airways plus alveolar dead space

apex of healthy lung is largest contributor of alveolar dead space.

Volume of inspired air that does not take part in gas
exchange.

VD = VT × [(Paco2 – Peco2)/ Paco2]

VT = tidal volume.
Paco2 = arterial Pco2.
Peco2 = expired air Pco2.

“Taco, Paco, Peco, Paco”

Question 10

Minute ventilation

VE

Answer 10

Total volume of gas entering lungs per minute

VE = VT × RR

Question 11

Alveolar ventilation

VA

Answer 11

Volume of gas per unit time that reaches alveoli

VA = (VT − VD) × RR

Question 12

Pulmonary vascular resistance (PVR)

Answer 12

PVR =(Ppulm artery – PL atrium)/cardiac output

Ppulm artery = pressure in pulmonary artery
PL atrium ≈ pulmonary capillary wedge pressure

R = 8ηl / πr4

η = viscosity of blood
l = vessel length
r = vessel radius