The following evaluations will be performed the day prior to the endoscopic evaluation :1) calculation of a clinical score based on the diurnal and nocturnal respiratory and nutritional tolerance of the UAO, 2) evaluation of the importance and the localisation of the UAO assessed by the acoustic reflection method, 3) measurement of the work of breathing, 4) recording of nocturnal gas exchange during at least 6 hours by s single monitor (Sentec™) which measures pulse oximetry (SaO2) and transcutaneous carbon dioxide (PtcCO2), and evaluation of sleep quality by actigraphy (recording of patient's movements by an Actiwatch™).