Critical Care

ROX Index

Predicts high-flow nasal oxygen success.

Education and reference only. Not a substitute for clinical judgement, local policy or product labelling. Always verify before clinical use. Values are calculated in your browser and never stored.

When to use

Use in patients on high-flow nasal oxygen (e.g. at ~2, 6 and 12 hours) to predict whether HFNO will succeed or whether escalation is likely.

Why use

A higher ROX index predicts HFNO success; a low or falling value flags likely failure.

Critical actions

ROX = (SpO₂/FiO₂)/RR. Enter FiO₂ as a fraction (e.g. 0.5, not 50). A ROX ≥4.88 at 12h predicts success; values should be trended, not used once.

Evidence & references

  1. Roca O et al. An index combining respiratory rate and oxygenation to predict outcome of HFNO. Am J Respir Crit Care Med. 2019.

About the creator

Roca O et al.

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