ΔfEIT images in patients without (1 to 6) and with (8 to 14) lung disorders between the PEEP steps used. PaO2/FiO2 ratio change (black) and compliance change (red) are presented next to each ΔfEIT image. Images containing a colour-coded 32 × 32 matrix, are generated by subtracting fEIT before the PEEP step from fEIT after each PEEP step. PEEP is decreased stepwise from 15 to 0 cm H2O. Each EIT image represents a thoracic slice with the ventral lung regions at the top and dorsal lung regions at the bottom.