Patients aged of 18 years or more, presenting with an acute respiratory failure without hypercapnia will be included in the study. Clinical and biological variables, dyspnea assessment, regional lung ventilation (electrical impedance tomography) and diaphragm function (ultrasound) will be evaluated at inclusion and at 2 hours, 4 hours and 48 hours after inclusion. In case of intubation, diaphragmatic function will be also evaluated with phrenic nerve stimulation technique.~Primary endpoint is intubation at day 7. Secondary endpoints are measurement of dyspnea, pulmonary ventilation and diaphragmatic function, also ventilator free days, ICU length of stay and mortality.
Modern management of acute respiratory failure aims to relieve dyspnea and anxiety by providing a non-invasive respiratory support. This approach tries to avoid endotracheal intubation, patient self inflicted lung injuries (PSILI) and diaphragmatic dysfunction. The present study aims to evaluate dyspnea, pulmonary regional ventilation and diaphragmatic function in patients with hypoxemic acute respiratory failure by different observations, and to bring risk factor for intubation out.