Fig. 3.

Expiratory muscle activity at different levels of assist. a Number of occlusions with expiratory muscle activity present or not, at three different levels of assist. b Magnitude of expiratory muscle activity, as indicated by the rise of gastric pressure (Pga) after occlusion, at three levels of assist (only in cases with expiratory muscle activity). Box: interquartile range, whiskers: 5–95 range, line at median, *p < 0.05 for assist level > 10 vs 8–10 cmH₂O, p < 0.0001 for assist level > 10 vs < 8 cmH₂O