Additional file 1. Method E1: Esophageal pressure measurement; Method E2: Ventilatory ratio calculation; Table E1: Lung recruitment maneuver and titration of the optimal positive end-expiratory pressure; Table E2: Effects of lung recruitment maneuver according to lung recruitability, in patients with positive end-expiratory transpulmonary pressure; Table E3: Hemodynamic changes during lung recruitment maneuver according to lung recruitability; Figure E1: Protocol for the lung recruitment maneuver in patient #12; Figure E2: Study flow chart; Figure E3: The receiver operating characteristic curve for the prediction of lung recruitment after the lung recruitment maneuver based on the recruitment-to-inflation ratio.