Figure 4.

Regional lung injury (quantitative). During spontaneous breathing (SB) low positive end-expiratory pressure (PEEP) increased injury in all lung regions, especially in dependent lung (severest among all groups); but high PEEP during SB reduced injury in all lung regions. In contrast, low PEEP during paralysis increased injury in nondependent and especially in middle lung regions (severest among all groups). High PEEP during paralysis reduced injury in nondependent and middle lung, but not in dependent lung. *P < 0.05 versus low PEEP + SB; ^#P < 0.05 versus low PEEP − SB; ^†P < 0.05 compared with other groups.