Comparison of ROX index (SpO/FIO ratio/respiratory rate) with a modified dynamic index incorporating PaO/FIO ratio and heart rate to predict high flow nasal cannula outcomes among patients with acute respiratory failure: a single centre retrospective study.

Background: High flow nasal cannula (HFNC) is increasingly being used to support patients with acute respiratory failure (ARF) and to avoid need for intubation. However, almost one third of the patients do not respond and require escalation of respiratory support. Previously, ROX index (SpO/FIO [SF] ratio/respiratory rate) has been validated among pneumonia patients to facilitate early recognition of patients likely to fail HFNC and therefore, benefit from timely interventions.