Patient-ventilator Asynchrony During Noninvasive Ventilation Assessed Using Diaphragm Ultrasonography

Fifteen healthy subjects under non-invasive ventilation will be have a recording of surface electromyogram, measurements of airway flows and pressures as well as a continuous ultrasound. The provocation of leaks on the Ventilation circuit and expiratory trigger modulation will generate a number of asynchronies between the subject and the respirator. These records will help to assess the agreement between the detection of asynchronies using electromyography of the respiratory muscles (technique of reference) and the diaphragmatic echography. We will also compare the respective performance of two techniques of diaphragmatic exploration (excursion and thickening of the diaphragm). A sensitivity of Ultrasound technique of at least 90% will be interpreted as a satisfactory index of concordance.