ROX — high-flow nasal cannula

ROX — high-flow nasal cannula

Principle

Calculate ROX from three measurements from the same observation. Compare with published thresholds only within the scope below, with contemporaneous measurements and an exact declared time.

Scope

Single Roca 2019 variant: adult, pneumonia with acute respiratory failure on HFNC. No threshold for other causes, paediatrics, NIV, conventional oxygen or invasive ventilation.

Interpretation limits

Comparisons use the unrounded value at exact 2, 6 and 12 h, without a tolerance window or neighbouring time point. Declared time is a tool-admission convention, not proof of clinical timing precision. Display uses two decimals. ROX decides neither intubation nor continuation of HFNC. No individual percentage or safe waiting period is calculated. A high index does not rule out deterioration; do not delay necessary care.

Formula and logic

ROX = (SpO₂ in % ÷ (FiO₂ in % ÷ 100)) ÷ respiratory rate in /min

Interpretation

2 h

<2.85: association with failure; 2.85 to <4.88: intermediate; ≥4.88: association with fewer intubations.

6 h

<3.47: association with failure; 3.47 to <4.88: intermediate; ≥4.88: association with fewer intubations.

12 h

<3.85: association with failure; 3.85 to <4.88: intermediate; ≥4.88: association with fewer intubations.

Definition version : 1.1.0

Sources

• Roca et al. — An Index Combining Respiratory Rate and Oxygenation to Predict Outcome of Nasal High-Flow Therapy

  2019 · Prospective multicentre validation; formula and thresholds at 2, 6 and 12 h in adults with pneumonia on HFNC.

• Roca et al. — Predicting success of high-flow nasal cannula in pneumonia patients with hypoxemic respiratory failure: The utility of the ROX index

  2016 · Derivation in adults with pneumonia on HFNC; descriptive result, not a treatment rule.