Ventilation Flashcards
define alveolar ventilation
rate at which air actually reaches alveoli
2 requirements of vent
- air must reach alveolus
2. lung must be perfused
only way to secrete CO2
increase vent
2 things which CO2 excretion depends on
- rate of alveolar vent
2. pACO2
how to assess paCO2
K(VCO2/VA)
name for area without alveoli
dead space
definition of resistance
change in pressure/flow
formula for resistance (poiseuilles law)
(8 x viscosity x length)/radius to the 4th
most important factor in resistanct
radius (to the 4th)
formula for resistance in series
R = R1 + R2 + R3…
formula for resitiance in parralell
1/R = 1/R1 + 1/R2 + 1/R3
normal volume of dead space
150ml
how to measure dead space
one breath of 100% O2 and measure N2 breathed out
- dead space = volume of 0% N2 and 1/2 of mixed volume
definition of alveolar dead space
anatomic dead space + unperfused portions of alveoli
normal ratio of dead space to tidal vol.
0.2 -0.35
