Ventilation Perfusion Relationships Flashcards
What is the alveolar gas equation?
PAO2 = PIO2 - (PaCO2)/R
ex: PIO2 = (760-47).21
barometric pressure - water vapor pressure
multiplied by percentage oxygen
What is a normal alveolar-arterial O2 gradient?
less than 20 mm Hg
What is implied if the alveolar-arterial oxygen gradient is larger than 20 mm Hg?
diffusion isn’t happening the way it should be
sthg wrong w/ the alveoli
List the zones of the lung in order of least intrapleural fluid to most intrapleural fluid.
Apex (Zone 1)
Middle (Zone 2)
Base (Zone 3)
List the zones of the lung in order of least negative intrapleural pressure to most negative intrapleural pressure.
Base (Zone 3)
Middle (Zone 2)
Apex (Zone 1)
List the zones of the lung from smallest alveoli at rest to largest alveoli at rest.
Base (Zone 3)
Middle (Zone 2)
Apex (Zone 1)
List the zones of the lung from smallest change in size of alveoli during inhalation to greatest change in size of alveoli during inhalation.
Apex (Zone 1)
Middle (Zone 2)
Base (Zone 3)
What is meant by the ventilation perfusion ratio (V/Q)?
volume of air inhaled per minute divided by cardiac output per minute
ex: 4L/min / 5L/min
What is an average ventilation perfusion ratio?
0.8
Is PaO2 high or low in a tissue with a high V/Q ratio?
high
Is PaCO2 high or low in a tissue with a high V/Q ratio?
low
Is the pH high or low in a tissue with a high V/Q ratio?
high
Is the volume of blood high or low in a tissue with a high V/Q ratio?
low
Is the PaO2 high or low in a tissue with a low V/Q ratio?
low
Is the PaCO2 high or low in a tissue with a low V/Q ratio?
high
