Oxygenation Index (OI)

Quantifies oxygenation efficiency in mechanically ventilated patients, especially for pediatric and severe ARDS.

fraction

Fraction of inspired oxygen (0.21 = room air, 1.0 = 100%)

cmH2O

Mean airway pressure from ventilator (not MAP = blood pressure)

mmHg

Arterial partial pressure of oxygen (from ABG)

Enter ventilator and ABG values to calculate OI

References

  1. Oxygenation Index - StatPearls - NCBI Bookshelf / NIH
  2. Oxygenation Index and P/F Ratio in ARDS - EBMcalc

Clinical Notes & Warnings

  • Mean airway pressure is from ventilator, NOT mean arterial pressure.
  • OI >40 for >6-12 hours indicates need for ECMO evaluation.
  • Pediatric ECMO criteria: OI >20-25 for ECMO consideration.
  • Requires arterial blood gas for PaO2.

Also known as Oxygenation Severity Index (OSI) when using SpO2 instead of PaO2. More sensitive than P/F ratio as it accounts for ventilator support level.