Oxygenation Index (OI)
- Category: Respiratory
- Version: v1.1.1
- Reviewed: Reviewed 6 Sep 2026
- Validation: Validation pending
OI = (mean airway pressure × FiO₂ × 100) ÷ PaO₂, with MAP in cmH₂O, FiO₂ a fraction, and PaO₂ in mmHg. The ×100 converts the fraction into the percentage form PALICC-2 prints, so the two renderings are the same number. Applying both conventions, or neither, is a 100-fold error, and it is the single most likely implementation mistake: if another calculator disagrees by a factor of 100, check this first. Bands (PALICC-2 2023, invasively ventilated) are OI < 4 below the PARDS oxygenation criterion, 4 to < 16 mild–moderate, and ≥ 16 severe.
Requires an arterial line, and is defined only on positive-pressure ventilation, conventional or HFOV. PALICC 2015 used three tiers, 4/8/16; PALICC-2 merged the lower two, and the severe cutoff did not move.
| Result | Interpretation |
|---|---|
| < 4 | OI < 4 — Below the PALICC-2 (2023) invasive-ventilation oxygenation criterion for PARDS (OI ≥ 4). Interpret in the full clinical context. |
| 4 to <16 | OI 4 to < 16 — Corresponds to the mild–moderate category for invasively ventilated children in PALICC-2 (2023) (OI ≥ 4 meets the oxygenation criterion; OI < 16). |
| ≥ 16 | OI ≥ 16 — Corresponds to the severe category for invasively ventilated children in PALICC-2 (2023) (OI ≥ 16). |
References
- Emeriaud G, López-Fernández YM, Iyer NP, et al; Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2) of the PALISI Network. Executive Summary of the Second International Guidelines for the Diagnosis and Management of Pediatric Acute Respiratory Distress Syndrome (PALICC-2). Pediatr Crit Care Med. 2023;24(2):143–168.PMID 36661420DOI 10.1097/PCC.0000000000003147
- 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.PMID 25647235DOI 10.1097/PCC.0000000000000350
- Khemani RG, Smith LS, Zimmerman JJ, Erickson S; Pediatric Acute Lung Injury Consensus Conference Group. Pediatric acute respiratory distress syndrome: definition, incidence, and epidemiology: proceedings from the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med. 2015;16(5 Suppl 1):S23–S40.PMID 26035358DOI 10.1097/PCC.0000000000000432
- Slaughter J, Sites J, Ballard H, Bauer J, Schadler A, Severyn N. Comparison of the oxygenation index and the oxygen saturation index as clinical indicators for neonatal ECMO. Front Pediatr. 2025;13:1586985.PMID 40630719DOI 10.3389/fped.2025.1586985
Reproduction rights
Freely reproducible.OI is an arithmetic formula; the PALICC 2015 / PALICC-2 diagnostic and severity thresholds (4, 8, 16) are facts (numbers, formulas), not copyrightable expression. No verbatim scale-item wording is embedded; surrounding guideline prose is paraphrased (oi-osi.md IP status).
Independent clinical validation: pending
Two independent clinical validators will be named here once review is complete.
- 2026-08-10v1.0.0Initial releaseInitial published text.
- 2026-09-03v1.1.0Formula correctionGrades the exact PALICC-2 and Berlin cut-points correctly. The arithmetic behind these indices is binary and the thresholds are decimal, so a value that IS the cut-point did not compute to it: an OI of exactly 16 evaluates to 15.999999999999998 from a mean airway pressure of 24, FiO2 0.60 and PaO2 90; an OSI of exactly 12 to 11.999999999999998; a P/F of exactly 100 to 100.00000000000001. Compared raw, all three placed the patient one band TOO MILD, the under-triage direction and never the reverse, while the page printed the rounded figure beside the milder label and appeared to contradict itself. The band matcher now treats a value within a millionth of a millionth of a bound as being on it, which is four orders above the floating-point residue and far below any difference a clinician draws. NO OTHER VALUE MOVES: a number genuinely below a cut-point still bands below it. Found 2026-09-03 by an independent recompute of every calculator from its published source; the same defect as the PRISM 14-day age term, in a different unit. On this score a child at the severe threshold of 16, or at the diagnostic threshold of 4, was graded one tier milder.
- 2026-09-06v1.1.1ClarificationAdded a one-line description for the catalogue card. No rule, threshold or reference changed.
Other respiratory scores
Important. For use by qualified health professionals as an informational and educational aid. It supports clinical judgment and does not replace it. Verify every result independently before making a clinical decision. This is not a medical device.