Fig. 2

Flowchart of the SBT process. Intensivists assessed the spontaneous breathing ability of the patient before the SBT process. When the patient exhibited spontaneous breathing of 10 times per minute or more, PAV was initiated. Under close observation and when the patient met the entry criteria, sedative drugs were reduced until the RASS was − 2 to 0. Intensivists observed the patient for 30–60 min and determined whether to extubate when the patient met the extubation criteria. SIMV: synchronized intermittent mandatory ventilation; PAV: proportional assist ventilation; SBT: spontaneous breathing trial