Comparison of ROX index with modified indices incorporating heart rate, flow rate, and PaO/FiO ratio for early prediction of outcomes among patients initiated on post-extubation high-flow nasal cannula therapy.

BACKGROUND

Incorporation of heart rate, flow rate, and PaO/FIO (PF) ratio to ROX index has been postulated to better predict high-flow nasal cannula (HFNC) usage outcomes in post-extubation setting. Therefore, we aimed to compare ROX index with new modified indices to predict HFNC outcomes in the post-extubation setting.

METHODS

This single-centre 6-year retrospective study included subjects initiated on HFNC post-extubation. The modified indices (ROX-HR, ROX-HR-Flow and POX-HR-Flow) incorporated HFNC flow rate, heart rate and substituted PF ratio for SF ratio. Evaluation was performed using AUROC and cut-offs assessed for prediction of HFNC outcomes.

RESULTS

Eighty-one subjects were initiated on HFNC post-extubation, of whom 67 patients (82.7%) had HFNC success. ROX-HR-Flow at 2 h post-HFNC initiation demonstrated the best prediction accuracy (AUROC 0.854, 95% CI 0.756-0.952). A ROX-HR-Flow > 12.25 at 2 h post-HFNC initiation was significantly associated with a lower risk of HFNC failure (Sensitivity 77.6% and Specificity 85.7%).

CONCLUSIONS

Our proposed modified index at 2 h post-HFNC initiation (ROX-HR-Flow), may facilitate early and accurate prediction of HFNC outcomes compared to ROX index among subjects initiated on HFNC in the post-extubation setting.