Figure 4.

Oxygenation changes and PaCO₂ levels during the first week of treatment. All patients showed improved oxygenation during treatment. The level of partial arterial pressure of carbon dioxide (PaCO₂) at day 1 was increased significantly in the decremental positive end-expiratory pressure (PEEP) titration group than the control group. The black bars indicate the control group and gray bars denote the decremental PEEP titration group. Values are expressed as the mean ± standard error of the mean (bars). *p < 0.05 between the control and decremental PEEP titration groups, ^†p < 0.05 compared with day 0 in the control group, ^‡p < 0.05 compared with day 0 in the decremental PEEP titration group.