Oxygenation Index (OI) Calculator
A severity measure of hypoxemic respiratory failure that accounts for the ventilator support required — the standard oxygenation metric in pediatric and neonatal disease, with the PALICC bands.
Written by Apex Respiratory Editorial Team
Enter as a fraction (0.5) or a percent (50).
Enter FiO₂, mean airway pressure, and PaO₂ to calculate the oxygenation index.
Reading the Oxygenation Index
Unlike the P/F ratio, OI includes mean airway pressure, so it rises when support climbs even if PaO₂ holds — capturing how hard the ventilator is working for a given oxygenation.
PALICC (2015) pediatric ARDS severity on invasive ventilation: OI < 4 below the threshold, 4 to < 8 mild, 8 to < 16 moderate, ≥ 16 severe. PALICC-2 (2023) consolidated the middle two into a single mild-to-moderate band (OI < 16) versus severe (≥ 16).
A persistently high OI (around 40 or more in the neonate) is a classic threshold for ECMO consideration; the oxygen saturation index (OSI, using SpO₂ instead of PaO₂) is a non-invasive surrogate when there is no arterial line.
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Sources
- Pediatric Acute Lung Injury Consensus Conference Group. Pediatric acute respiratory distress syndrome: consensus recommendations from the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med. 2015;16(5):428-439.
- Emeriaud G, Lopez-Fernandez YM, Iyer NP, et al. Executive summary of the Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2). Pediatr Crit Care Med. 2023;24(2):143-168.