Oxygenation Index (OI)
Severity of hypoxemic respiratory failure in ventilated patients.
What is Oxygenation Index (OI)?
Severity of hypoxemic respiratory failure in ventilated patients. Oxygenation Index is intended for use in: Adults.
How to Use the Oxygenation Index Calculator
- Enter FiO2 in %.
- Enter Mean airway pressure in cmH2O.
- Enter PaO2 in mmHg.
- Click Calculate to see your result and interpretation.
Formula & Version
This calculator uses formula version 1.0, last reviewed September 2026.
Clinical Considerations & Limitations
- Most established in neonatal/pediatric ventilated respiratory failure (e.g. ECMO-referral discussions) — used more cautiously in adults, where OSI (using SpO2) is sometimes substituted when an arterial line is unavailable.
References
- Standard critical-care formula: OI = (FiO2 × Mean Airway Pressure × 100) ÷ PaO2
Frequently Asked Questions
What is Oxygenation Index (OI)?
Severity of hypoxemic respiratory failure in ventilated patients.
Who is Oxygenation Index intended for?
Adults. Always confirm applicability to your specific patient before use.
What are the limitations of Oxygenation Index?
Most established in neonatal/pediatric ventilated respiratory failure (e.g. ECMO-referral discussions) — used more cautiously in adults, where OSI (using SpO2) is sometimes substituted when an arterial line is unavailable.
What formula or reference does Oxygenation Index use?
Standard critical-care formula: OI = (FiO2 × Mean Airway Pressure × 100) ÷ PaO2
Is Oxygenation Index a diagnosis?
No. Oxygenation Index produces a score or estimate to support clinical decision-making — it is not a diagnosis and should be interpreted alongside full clinical judgement.
