Figure 1

EELV WI-WO and EELV CT at each experimental condition (upper panel), with corresponding RR, PEEP, and V T (lower panel). Values are mean ± standard deviation. ARDS, experimental acute respiratory distress syndrome; EELVWI-WO, end-expiratory lung volume assessed with the nitrogen washin-washout technique; EELVCT, end-expiratory lung volume assessed by computed tomography; optimal PEEP, optimal PEEP level according to one of the three methods (see text for details); PEEP, positive end-expiratory pressure; RR, respiratory rate; VT, tidal volume.