Fig. 1

Study design. Eleven morbidly obese patients ventilated in pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP), considered as baseline settings, were included to randomly perform the five weaning test modalities of the study before extubation: PSV 7 cmH2O + PEEP 7 cm H2O; PSV 0 cmH2O + PEEP 7 cmH2O; PSV 7 cmH2O + PEEP 0 cmH2O; PSV 0 cmH2O + PEEP 0 cmH2O or the T piece. All measurements were obtained after 15 minutes of each test. A 10-minute period of return to baseline state (with initial settings of ventilation parameters before the first weaning test) was performed between each test and before extubation. WT weaning test