Fig. 1

Intra-individual relationships between ΔPdi and TFdi for mechanically ventilated (MV) patients (A) and healthy subjects (C). Relationships between ΔPdi and TFdi when breathing cycles were averaged for all participants during each condition for MV patients (B) and healthy subjects (D). − 25%: initial settings minus 25% inspiratory help, + 25%: initial settings plus 25% more inspiratory help, PEP 0: zero positive end-expiratory pressure, SBT: spontaneous breathing trial. Healthy subjects performed spontaneous breathing (SB) and ventilation against inspiratory threshold at 10, 20, 30, 40 and 50% of maximal inspiratory pressure (MIP)