Fig. 2. Exhaled breath condensate (EBC) cytokine concentrations in healthy control subjects and on days 1, 3, and 5 of mechanical ventilation under zero end-expiratory pressure (ZEEP) or positive end-expiratory pressure (PEEP). Data are presented as individual values. Statistical analyses of skewed values, which was the case for the four cytokines shown in panels A, B, E, and F, were performed after logarithmic transformation to achieve normality. Values of cytokines shown in panels C and D were normally distributed and were analyzed as such. Patterns of all EBC cytokines were analyzed by two-way ANOVA for repeated measures (ANOVARM); interleukin (IL)-10 was the sole cytokine to show significant interaction between time and PEEP (P < 0.05). *P < 0.05 as compared with day 1 corresponding values within the group by one-way ANOVARM and Tukey–Kramer test. §P < 0.05. ¶P < 0.001 as compared with corresponding control values by one-way ANOVA and Tukey–Kramer test. TNF = tumor necrosis factor.