Calculates the Alveolar-Arterial Gradient to assess degree of shunting and V/Q mismatch.

A-a O2 Gradient = [ (FiO2) * (Atmospheric Pressure - H2O Pressure) - (PaCO2/0.8) ] - PaO2 from ABG




1. Atmospheric Pressure  


mmHg

2. PaO2 (from ABG)  


mmHg

3. FiO2 (Room Air: 21%)  


%

4. PaCO2  


mmHg

5. Age (for expected A-a gradient)  


years