Example: A patient has a pO2of 85mmHg on ABG while receiving 5 liters/minute of oxygen. 5 L/min = 40% oxygen = FIO2of 0.40. The P/F ratio = 85 divided by 0.40 = 212.5. How to Calculate SpO2 to PaO2 (when no ABG available) When the PaO2is unknown because an ABG is not avai...