ROX Index to Predict Risk of Intubation

Predict risk of intubation at 2, 6 and 12 hours in hypoxemic respiratory failure. Not yet validated for COVID-19


During high-flow nasal cannula (HFNC) therapy in patients with acute hypoxemic respiratory failure, it can be desirable not to delay intubation and have an adverse event.

The ROX index, defined as the ratio of oxygen saturation as measured by pulse oximetry/FIO2 to respiratory rate, has been assessed as a predictor of the need to intubate in patients received HFNC oxygen therapy.

Prediction accuracy of the ROX index increased over time with AUC of 0.679 at 2 h, 0.703 at 6 hours and 0.759 at 12 hours.

ROX &ge:4.88 at 2, 6 and 12 hours after HFNC initiation was associated with a lower risk for intubation.

Predictors of HFNC failure include:

  • ROX <:2.85 at 2 hours
  • ROX <:3.47 at 6 hours
  • ROX <:3.85 at 12 hours


Roca O et al.

American Journal of Respiratory and Critical Care Medicine 2019 June 1, 199 (11): 1368-1376.

The ROX Index to Predict Risk of Intubation calculator is created by QxMD.

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1. SpO₂

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SpO₂ represents peripheral capillary oxygen saturation

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