Awake Prone Position to Reduce Ventilation Inhomogeneity in COVID-19 Acute Respiratory Failure

"Study of physiological effects of awake prone position in COVID 19 patients on lung inhomogeneity assessed by Electrical Impedance Tomography (EIT), gas exchange and dyspnea score (Borg Scale).~Measurements will be performed at baseline (on supine position), then patients will be randomized on the order of position, either supine then prone, either prone then supine. Each period will last at least 2 hours. EIT records will be performed during the last 30 minutes of each period, blood gas and dyspnea score at the end of each period."