🫁 Oxygenation Index (OI)
Calculate the oxygenation index (OI) for ventilated patients, central to paediatric ARDS grading.
Clinical takeaway
Accounts for mean airway pressure, unlike the P/F ratio.
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When to use
Grade oxygenation severity incorporating ventilator support.
How it works
OI = (FiO₂% × mean airway pressure) / PaO₂. PALICC: 4–8 mild, 8–16 moderate, ≥ 16 severe.
Key points
- Accounts for mean airway pressure, unlike the P/F ratio.
- Higher OI = worse oxygenation.
- Oxygen saturation index (OSI) is a non-invasive analogue.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| FiO₂ | 0.6 fraction |
|---|---|
| Mean airway pressure | 15 cmH₂O |
| PaO₂ | 70 mmHg |
→OI12.9
- Severity：Moderate
- Formula：OI = (FiO₂% × mean airway pressure) / PaO₂
Frequently asked questions
- What is Oxygenation Index (OI)?
- Calculate the oxygenation index (OI) for ventilated patients, central to paediatric ARDS grading.
- How is Oxygenation Index (OI) calculated? What is the core formula?
- OI = (FiO₂% × mean airway pressure) / PaO₂. PALICC: 4–8 mild, 8–16 moderate, ≥ 16 severe.
- When is Oxygenation Index (OI) used?
- Grade oxygenation severity incorporating ventilator support.
- What are the key clinical points for Oxygenation Index (OI)?
- Accounts for mean airway pressure, unlike the P/F ratio. Higher OI = worse oxygenation. Oxygen saturation index (OSI) is a non-invasive analogue.
- What are the limits and cautions when using Oxygenation Index (OI)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Oxygenation Index (OI) calculated in practice? Can you show a worked example?
- Inputs: FiO₂ 0.6 fraction, Mean airway pressure 15 cmH₂O, PaO₂ 70 mmHg → Result: OI 12.9（Severity: Moderate, Formula: OI = (FiO₂% × mean airway pressure) / PaO₂）