Figure 1.

Effects of loss of aeration on the driving pressure. The use of 500 mL tidal volume applied to a lung with no loss of aeration and high compliance does not result in tidal hyperinflation (A). The same tidal volume applied to a lung with lower compliance and relevant loss of aeration can result in relevant tidal hyperinflation, as suggested by the presence of high ∆P and a stress index above 1 (B). The reduction of V_T to 250 mL can balance this phenomenon (C). V_T, tidal volume; Crs, compliance of the respiratory system; ∆P, driving pressure.