Effect of Three Modalities of Spontaneous Breathing Tests on Respiratory Efforts in Tracheostomized Patients

Datas are lacking concerning weaning from mechanical ventilation for tracheostomized patients. In particular, the effect of different modalities of spontaneous breathing trials on respiratory effort has not been extensively described. This crossover physiology study will include 18 tracheostomized patients ventilated for more than 72 hours. The objective of this study is to compare the effect of three different modalities of SBTs on respiratory effort in tracheostomized patients. The modalities tested are : Pressure Support Ventilation (PSV level 5 cmH2O, PEEP 5 cmH2O), T-piece test and high-flow Oxygen. Each modality is applied in a randomized order, during 30 minutes. During every modality tested, esophageal and gastric pressure, expired CO2, and comfort will be monitored, in addition to standard monitoring. Based on esophageal pressure monitoring, patient's respiratory efforts can be calculated either by esophageal pressure-time product and work of breathing. Pressure generated by inspiratory muscles will also be assessed.