Fig. 1

Timeline of study protocol. Patients who underwent invasive mechanical ventilation (MV) for > 48 h and who were eligible for their first spontaneous breathing trial (SBT) were included. An integrated ultrasound assessment of the heart, lungs, and diaphragm was performed before and 30 min after starting a 2-h SBT with low-level pressure support. After successfully passing the SBT, the physicians in charge decided whether to extubate, independent of the investigators. Weaning outcome was monitored for 48 h. Weaning failure was defined as failure of SBT, reintubation, or non-invasive ventilation within the following 48 h