The oxygenation index calculator takes map, fio₂ and pao₂ and returns oxygenation index (oi) and pao₂/fio₂ ratio. It is built for quick answers, for checking somebody else’s arithmetic, and for the moments when a formula book is not within reach.
What Is the Oxygenation Index Calculator?
The oxygenation index calculator gives you an estimate of oxygenation index (oi) and pao₂/fio₂ ratio based on map, fio₂ and pao₂.
It is a quick reference figure rather than a diagnosis, and it is most useful for tracking how a number moves over time rather than for interpreting a single reading.
How the Oxygenation Index Estimate Is Worked Out
The calculation follows published reference relationships, so it is a reasonable approximation when the inputs are accurate. It assumes an average adult and does not account for individual variation.
If you are comparing two people, or the same person over a period of weeks, keep the method and the inputs identical. A change in the method can easily look like a change in the person.
What This Calculator Does Not Do
It does not diagnose anything, and it does not replace advice from a clinician. If a figure comes out at an extreme, or if it differs sharply from what you expect, that is a reason to speak to a professional rather than to adjust the inputs.
Nothing you type here is stored or sent anywhere. The whole calculation happens in your browser.
A Worked Example
Working through an example, with map set to 10, fio₂ set to 5, pao₂ set to 2, the calculator returns oxygenation index (oi) of 2,500, and pao₂/fio₂ ratio of 0.4. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out oxygenation index (oi)?
Enter map, fio₂ and pao₂. The calculator then works through the relationship and reports oxygenation index (oi) and pao₂/fio₂ ratio.
What does the oxygenation index actually calculate?
It takes map, fio₂ and pao₂ and converts them into oxygenation index (oi) and pao₂/fio₂ ratio using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter map?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Does anything you type get stored?
No. The whole calculation runs inside your browser, and nothing you enter is uploaded, logged or sent anywhere.