Formulas
Pulmonary
- Alveolar-arterial O2 gradient, pATM at sea level 760 mmHg
- PAO2 - paO2
- A-a O2 gradient = [FiO2 x (pATM - pH2O)] - (paCO2/0.8) - paO2
- =[FiO2 x (760 - 47)] - (paCO2/0.8) - paO2
- Normal for young adult non-smoker < 15 mmHg at sea level at RA
- Normal estimate by age < (age/4) + 4[1]
- ↑ Nickson C. Lifeinthefastlane. A-a gradient. http://lifeinthefastlane.com/ccc/a-a-gradient/.
