INSPIRatory Efforts Estimation Under High-flow Nasal Oxygen

High-flow nasal oxygen (HFNO) is recommended as first-line treatment to prevent intubation in acute hypoxemic respiratory failure and to prevent reintubation after extubation (alone in patients at low-risk of extubation failure, alternating with noninvasive ventilation in patients at high-risk of extubation failure). It consists in delivering high flow of heated and humidified gas enriched with oxygen through nasal cannulas. However, HFNO failure occurs in 30 to 50% of cases in acute hypoxemic respiratory failure and 10 to 20% of cases after extubation. Accumulating data suggest that strong inspiratory efforts and their persistence are associated with HFNO failure. However, the monitoring of inspiratory efforts is challenging, especially in patients breathing spontaneously through the nose under HFNO. On a bench study, the investigators have developed an algorithm estimating noninvasively inspiratory efforts under HFNO based on the analysis of tracings of pressure and flow delivered by the HFNO device using an extracorporeal sensor. The coefficient of determination of the algorithm was high (R2=0.92). This pilot study aims at testing the feasibility of estimating inspiratory efforts in patients treated with HNFO.