ALVEOLUS 100mmHg PACO₂ 40 mmHg Bronchi Terminal bronchiole Adjacent alveoli Interalveolar septum Pulmonary capillary Alveolar–capillary membrane Inspired PIO₂ 150 Alveolar PAO₂ 100 CO₂ displacement −50 Respiratory quotient R 0.80 A–a gradient 5 Diffusion gradient 60 Arterial PaO₂ 95 values in mmHg · R is unitless
Inspired PIO₂ 150
Alveolar PAO₂ 100
CO₂ displacement −50
A–a gradient 5
Diffusion gradient 60
Arterial PaO₂ 95
Respiratory quotient R 0.80
values in mmHg
R is unitless
O=O oxygen O=C=O carbon dioxide red cells oxygenating
Altitude0 m
FiO20.21
PaCO240
Respiratory quotient0.80
Temperature37.0 °C
Measured PaO295
PAO2 = FiO2 × (Pb − PH2O) − PaCO2 ÷ R
=0.21×(760−47)−40÷0.80
=0.21×713−50
=150−50
=100 mmHg
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