VOX Index

Non-invasive ventilation (NIV) is an evidence-based treatment for patients with acute respiratory failure due to an exacerbation of Chronic Obstructive Pulmonary Disease (COPD). In patients with COPD and acute hypercapnic respiratory failure, NIV improves gas exchange, reduces the work of breathing, and decreases the length of hospital stay and mortality \[1\]. Furthermore, when compared to invasive ventilation, NIV leads to fewer complications, such as ventilator-related infections \[2\]. These findings have resulted in guideline recommendations for the use of NIV in acute respiratory failure due to an exacerbation of COPD \[3\].NIV failure has been defined as the need for endotracheal intubation (ETI) or death. Its rate varies greatly between 5% and 60%, depending on numerous factors \[4\]. The Volume Oxygenation (VOX) index, initially developed to predict treatment failure of high flow nasal cannula therapy, has demonstrated the ability to estimate early increases in respiratory drive. Within the first 2 h, the VOX index exhibits a discriminative potential of 0.88 (95 % CI 0.79-0.97) in predicting HFNC failure \[5\]. Based on this premise, we hypothesize that the VOX index could be a predictive tool for NIV treatment failure.