Breathing
Oxygenation index and oxygen saturation index
How much ventilator support a baby needs for their oxygen level: the oxygenation index (with an arterial PaO2) and the oxygen saturation index (with SpO2, when there is no arterial gas).
For education. Check against your unit's guidance and a second clinician before use.
cmH2O
Arterial sample, for the oxygenation index.
Preductal, for the oxygen saturation index.
%
Enter the mean airway pressure, FiO2, and a PaO2 or SpO2.
How this is calculated
- OI = mean airway pressure (cmH2O) × FiO2 (%) ÷ PaO2 (mmHg). PaO2 in kPa is converted to mmHg (× 7.5).
- OSI = mean airway pressure (cmH2O) × FiO2 (%) ÷ SpO2 (%).
Sources
Checked by NICUlearn, 6 Oct 2026.