Inclusion Criteria:  Invasive mechanical ventilation> 48h Deemed ready to perform a spontaneous breathing trial, according to current guidelines (readiness-to-wean criteria) Decision to perform a spontaneous breathing trial Patients or proxy who do not object to participation in the study  Exclusion Criteria:  Age < 18 Pregnancy Richmond Analgesia And Sedation scale < 2 or > 2 Patient under legal protection