Work out the oxygenation index from inspired oxygen fraction, mean airway pressure and arterial oxygen.
Result
How to use this tool
Use percent, for example 100 for pure oxygen, not 1.0.
Use cmH2O from the ventilator.
Use arterial oxygen in mmHg from the blood gas.
Higher values mean worse oxygenation for the ventilator support used.
Formula & worked example
FiO2 100%, mean airway pressure 15 cmH2O and PaO2 75 mmHg give 100 x 15 / 75 = 20.0, a moderate oxygenation failure range.
Limitations — read this before you rely on it
Intensive-care calculation aid only. It does not set ventilation or ECMO decisions. This tool is for education only and is not medical advice. Talk to a clinician about any result that worries you, and never change treatment because of a calculator result.
Frequently asked questions
FiO2 times mean airway pressure divided by PaO2. It rises when more oxygen and pressure are needed for the same blood oxygen.
The P to F ratio ignores ventilator pressure. The oxygenation index includes it, so it reflects the cost of achieving that oxygen level.
Values persistently over 40 are often cited in specialist assessment, but ECMO decisions use many more factors.
Both, but most often in neonatal and paediatric intensive care.
No. Trends, cause, other organ function and specialist judgement all matter.