Fig. 1

Data obtained with inspiratory and expiratory hold maneuvers in the five PS steps in the study population (n = 18). At each PS step, the respiratory system distending pressure, i.e. plateau pressure (Pplat), equals the sum of peak airway pressure plus pressure-muscle-index (PMI). Positive end-expiratory pressure (PEEP) was left unchanged during the study protocol (Fig. 1A). Since respiratory system static compliance (Crs) did not significantly vary across the study steps (P = 0.119), tidal volume (Vt) varied proportionally to the applied driving pressure (∆P) and reached values above 8 mL/Kg when PS was raised above the clinically set (Fig. 1B). Data are presented as mean ± SD. Ppeak, peak airway pressure