Division of General Internal Medicine

Online Clinical Calculator

A-a Oxygen Gradient

PaO2 (partial pressure of arterial O2): mmHg
PaCO2 (partial pressure of arterial CO2): mmHg
Atmospheric Pressure:
Inspired Oxygen Concentration (FiO2): Room Air (21 percent)
Other:
A-a Gradient = mmHg
A-a (O2) = (FiO2%/100) * (Patm - 47 mmHg) - (PaCO2/0.8) - PaO2
(all units mmHg)

General Internal Medicine
9200 W. Wisconsin Ave.
Milwaukee, WI. 53226
Last Update: 3/9/99. Developed by Charles Hu, Ron Kneusel & Gary Barnas M.D.
Comments to: barnas@mcw.edu