The Lungs At Altitude Flashcards
1
Q
Equation for pressure of inspired gas?
Pi (gas) =
A
Pi (gas) = Patm x Fi (gas)
Atmospheric pressure x fraction of gas
2
Q
What is the PiO2 at normal altitude (sea level)?
A
PiO2 = 100kPa x 0.21 = 21kPa
3
Q
Equation for alveolar O2 (PAO2)?
A
PAO2 = PiO2 - PaCO2/R
R is normally 0.8
4
Q
Equation for pressure of arterial O2 (PaO2)?
A
PaO2 = PAO2 - (A - aDO2) Arterial = alveolar - (alveolar/arterial conc gradient - normally 1)
5
Q
What is PaO2 usually?
A
1kPa less than PAO2
Natural V/Q mismatch
6
Q
Equation for PaCO2?
A
K VCO2/VA
Ventilated CO2/ventilated alveoli
7
Q
Typical value of PaCO2?
A
4.5 to 6 kPa
8
Q
Typical value of PaO2?
A
10.5 to 13.5 kPa
9
Q
Typical value of pH
A
7.35 to 7.45
10
Q
Typical value of atm?
A
100kPa
