ToolsCalculators
ROX Index for Intubation after HFNC
Predicts high-flow nasal cannula success versus need for intubation.
ROX Index for Intubation after HFNC
SpO2
%
FiO2 delivered
%
Respiratory rate
/min
Complete the fields above to see the result.
When to use
- Deciding whether a patient with hypoxaemic respiratory failure is likely to succeed on high-flow nasal cannula.
- Serial reassessment at roughly 2, 6, and 12 hours after HFNC initiation.
Formula
ROX = (SpO2 / FiO2) / respiratory rate, with FiO2 expressed as a fraction. Higher values favour HFNC success; the validated success threshold is >=4.88.
Pearls and pitfalls
- A rising ROX over time is reassuring; a falling or persistently low value argues for escalation.
- Validated in pneumonia-related hypoxaemic failure; extrapolate cautiously to other aetiologies.