Impact of ROX and POX indices on NIV outcome in acute respiratory failure a single study center, retrospective cohort study

Abstract Background Non-invasive ventilation (NIV) is a critical supportive therapy for acute respiratory failure (ARF). However, delayed intubation in high-risk cases with failure of NIV can be fatal. Early diagnosis of cases at NIV failure risk may improve results. Objectives To assess the predictive power of pulse oximetry/FIO2 to respiratory rate (ROX) and PaO2/FIO2 to respiratory rate (POX) indices alone and with the incorporation of heart rate (POX-HR and ROX-HR) in predicting NIV outcome in ARF. Methods This retrospective trial involved 55 ARF cases admitted to the Respiratory Intensive Care Unit (RICU) at Kafr Elsheikh University Hospital in the period from January 2023 and January 2024. Clinical, laboratory, and arterial blood gas data were reported retrospectively from cases records at baseline, 2, and 6 h after NIV initiation. ROX, ROX-HR, POX, and POX-HR were calculated, and their predictive performance for NIV failure or success was evaluated. Results Of 55 patients, 45 (82%) achieved NIV success, while 10 (18%) demonstrated NIV failure. NIV failure cases had significantly lower ROX-HR, ROX, POX, and POX-HR values at 2 and 6 h ( p < 0.001). ROC analysis demonstrated superior predictive performance of indices incorporating HR, particularly POX-HR at 6 h (AUC = 0.994). Conclusion Oxygenation indices (ROX and POX) accurately predicted NIV outcomes in ARF. Incorporating HR (ROX-HR and POX-HR) improved predictive accuracy, with POX-HR at 6 h being the most reliable early indicator of NIV outcome. Categories Pulmonology, RICU.