Lung regions of interest percentage. The figure represents the relative impedance changes in each lung region, from ventral to dorsal, observed during the different study steps. The P values are as follows: Friedman repeated measures ANOVA for ventral region P = 0.218; Friedman repeated measures ANOVA for midventral region P = 0.012; **P = 0.064 PS_cli1versus NAVA_40%; *P = 0.010 PS_cli2versus NAVA_40%; Friedman repeated measures ANOVA for middorsal region P = 0.339; Friedman repeated measures ANOVA for dorsal region P = 0.062. NAVA_40%, neurally adjusted ventilatory assist at 40% unloading; NAVA_60%, neurally adjusted ventilatory assist at 60% unloading; PS_cli1. pressure support; PS_cli2, same as PS_cli1.