EIT waveforms in experimental lung injury—spontaneous versus mechanical breaths. Note that the early inflation in the dependent region (Zones 3 and 4) was accompanied by concomitant deflation of nondependent region (Zones 1 and 2), indicating movement of air from nondependent to dependent lung (i.e. Pendelluft). Note that under the same tidal volume, spontaneous breathing during mechanical ventilation unsuspectedly increased dependent lung inflation (Zones 3 and 4) due to Pendelluft. Adapted with permission of the American Thoracic Society Copyright © 2014 American Thoracic Society (Ref. ).