Fig. 1.

Time-line of the study protocol. Patients requiring mechanical ventilation for at least 48 h (H) were consecutively included. After 30 min of a T-tube spontaneous breathing trial (SBT), patients breathing patterns were examined. We used a multimodal evaluation combining ultrasound evaluation of diaphragmatic displacement and spirometry. At the end of a 2-h SBT, the treating physician decided to extubate or to reinstitute mechanical ventilation without being aware of the results of the ultrasound exploration of the diaphragm. Weaning success was monitored for a 48-h follow-up period; the reinstitution of mechanical ventilation during or at the end of the SBT, reintubation within 48 h, or the use of non-invasive ventilation (NIV) within 48 h from extubation were registered as a failed weaning attempt