Performance of ROX index in predicting reintubation rate of postextubation high-flow nasal cannula therapy in patients with hypercapnic respiratory failure

Background
There is growing evidence to support the use of high-flow nasal cannula (HFNC) in patients with postextubation hypercapnic respiratory. Thus, this study was conducted to assess the performance of the ROX index to detect the risk of failure of HFNC in postextubation hypercapnic respiratory failure patients.


Patients and methods
In this prospective, randomized controlled trial, 170 mechanically ventilated patients with hypercapnic respiratory failure who achieved the parameters of planned extubation were randomized to either HFNC, noninvasive ventilation (NIV), or venturi mask (VM). After extubation, arterial blood gases, vital signs, and ROX index were recorded at 2, 12, 24, and 48 h. The main outcome was the accuracy of the ROX index at different time intervals to detect the possibility of failure of HFNC after extubation.


Results
Patients who received HFNC, had lower respiratory rates, higher oxygenation (PaO2), and lower PaCO2 levels as compared with NIV and VM groups at all times of recording. Also, the reintubation rate was less in patients in HFNC group significantly. Our findings revealed that the ROX index with a cutoff point less than 5.5% at 2 h had 88.8% the best diagnostic accuracy for detection of reintubation in hypercapnic respiratory failure patients.


Conclusion
The ROX index is a reliable tool to detect hypercapnic respiratory failure patients with reintubation risk after postextubation HFNC treatment. HFNC group had better oxygenation and lower PaCO2 levels than NIV and VM.