Respiratory Phys - Lung Volumes Flashcards
Lung volumes (LITER) mnemonic:
Lung volumes (in order on graph) IRV TV ERV RV
Inspiratory Reserve Volume (IRV)
Air that can still be breathed in after normal inspiration
Tidal Volume (TV)
Air that moves into lungs with each quiet inspiration 500 mL (typically)
Expiratory Reserve Volume (ERV)
Air that can still be breathed out after normal expiration
Residual Volume (RV)
Air in lung after maximal expiration; Cannot be measured on spirometry
Inspiratory capacity (IC)
IRV + TV (Inspiratory Reserve Volume) + (Tidal Volume)
Functional Residual Capacity (FRC)
RV + ERV (volume in lungs after normal expiration) (Residual Volume) + (Expiratory Reserve Volume)
Vital Capacity (VC)
TV + IRV + ERV Maximum volume of gas that can be expired after a maximal inspiration
Total Lung Capacity (TLC)
IRV + TV + ERV + RV Volume of gas present in lungs after maximal inspiration
Physiologic Dead Space Equation
VD = VT x (PaCO2 - PECO2) / (PaCO2)
VD = Physiologic Dead Space
VT = Tidal Volume
PaCO2 = arterial PaCO2
PECO2 = expired air PCO2
Taco, Paco, PEco, Paco
Largest contributor of functional dead space in healthy lung:
Apex of healthy lung
Volume of inspired air that does not take part in gas exchange:
Physiologic Dead Space
Minute Ventilation (VE):
Total volume of gas entering the lungs per minute
VE = VT x respiratory rate
VT = Tidal Volume
Alveolar Ventilation (VA)
Volume of gas per unit time that reaches the alveoli
VA = (VT - VD) x RR
At what lung volume is the inward pull of lung balanced by outward pull of chest volume?
FRC
