Fig. 2. Illustration of overall time course for the study protocol. HFO = high-frequency oscillation; ITPV = intratracheal pulmonary ventilation; Paw = mean airway pressure; PCV = pressure control ventilation; PEEP = positive end-expiratory pressure; RM after = lung recruitment maneuvers after identification of optimal PEEP/Paw; RM initial = lung recruitment maneuvers before identification of optimal PEEP/Paw.