Fig. 1. Experimental protocol. ALI was induced by hydrochloric acid intrabronchial instillation. PEEP titration was performed by applying incremental (5–10 to 15–20 cm H2O) and decremental PEEP (20–15 to 10–5 cm H2O). At the end of each PEEP level (20 min), RM were performed by inflating the lungs three times using the continuous positive airway pressure-mode on the ventilator, until an inspiratory pressure of 40 cm H2O was reached and sustained for 20 s. G1 (group 1): animals with normal lung without mechanical ventilation; G2 (group 2): animals without ALI and ventilated with PEEP 5 cm H2O for 1 h; G3 (group 3): animals without ALI and treated with incremental and decremental PEEP; G4 (group 4): animals without ALI and treated with incremental and decremental PEEP and RM; G5 (group 5): animals with ALI and ventilated with PEEP 5 cm H2O for 1 h; G6 (group 6): animals with ALI and treated with incremental and decremental PEEP; G7 (group 7), animals with ALI and treated with incremental and decremental PEEP and RM. ALI = acute lung injury; PEEP = positive end-expiratory pressure; RM = recruitment maneuvers.
