calculators | A-a Oxygen Gradient Feb 21, 2005 Viewed: 1046 PaO2 (partial pressure of arterial O2): mmHgPaCO2 (partial pressure of arterial CO2): mmHgAtmospheric Pressure: atmospheric pressure in mmHg altitude in feetaltitude in meters Inspired Oxygen Concentration (FiO2): Room Air (21 percent) Other: known oxygen concentration (percent)oxygen delivered (L/min) A-a Gradient = mmHg A-a (O2) = (FiO2%/100) * (Patm - 47 mmHg) - (PaCO2/0.8) - PaO2 (all units mmHg) Provided by ArmMed Media Please enable JavaScript to view the comments powered by Disqus.