Fig. 1. Study design. ARDS = acute respiratory distress syndrome; ARDS network strategy = ARDSNet strategy; BAL = bronchoalveolar lavage; CT = computed tomography; FIO2= inspired O2fraction; PEEP = positive end-expiratory pressure; PPLAT= end-inspiratory plateau pressure; VT= tidal volume. All patients in the Lower ARDSNet /Carbon Dioxide Removal arm met pH criteria for carbon dioxide removal and were therefore connected to the veno-venous bypass.