Acid-base
Alveolar-arterial O₂ gradient
PAO₂ − PaO₂. Distinguishes hypoventilation from V/Q mismatch/shunt/diffusion.
Required inputs
- FiO₂ (0.21-1.0)
- PaO₂ (mmHg)
- PaCO₂ (mmHg)
- Age (yrs)
- Atmospheric P (mmHg)
Equation or source
West JB. Respiratory Physiology, 11e.