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⚕️ For clinical reference only. Not a substitute for professional judgment.
ROX Index ICU / HFNO
Ratio of SpO2/FiO2 to respiratory rate — predicts high-flow nasal oxygen (HFNO) failure. ROX <4.88 at 12h predicts intubation need.
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Enter oxygenation parameters
Enter SpO2, FiO2 and respiratory rate on current HFNO settings.
Current HFNO Parameters
fraction (0.21–1.0)
breaths/min
Formula & Thresholds
ROX Index = (SpO2 / FiO2) / Respiratory Rate
Failure thresholds (predict need for intubation):
At 2h: ROX <2.85
At 6h: ROX <3.47
At 12h: ROX <4.88 (primary threshold)
Values above threshold: HFNO likely to succeed
When to use
- Hypoxaemic respiratory failure on HFNO — serial assessment
- Guides escalation to NIV or invasive ventilation
- Validated in pneumonia and COVID-19 related ARDS
- Use alongside clinical assessment — not as sole decision tool
References
- Roca O et al. An index combining respiratory rate and oxygenation to predict outcome of nasal high-flow therapy. Am J Respir Crit Care Med. 2019.