Oxygen Index: OI = (FiO2 * Paw) / PaO2
0-25 index : Good outcome. 25-40 index : Chance of death > 40%. 30-1000 index : > 4 hours – Increased risk of worsening / death. 40-1000 index : Consider ECMO (ExtraCorporeal Membrance Oxygenation).
FiO2: Fraction of inspired oxygen (%). Paw: Mean airway pressure (mmHg). PaO2: Partial pressure of oxygen in arterial blood (mmHg).