Plasma concentrations of cytokines, neutrophil elastase, and Clara cell protein 16 (CC16). The plasma concentrations of cytokines (A), neutrophil elastase (B), and CC16 (C) were plotted at 0 and 60 min time points in both tidal volume (V_T) groups. No significant differences were observed in cytokine concentrations at any time point and between the V_T groups. The mean level of neutrophil elastase significantly increased from 0 to 60 min in the V_T6 group. The mean concentration of CC16 increased from 0 to 60 min in the V_T10 but not in the V_T6 group. Graphs represent mean and SD. Comparisons between different time points were performed with a paired t test. The change scores of continuous variables from 0 to 60 min time points were compared between the two V_T groups using an independent t test. No significant difference was observed between the V_T groups. *P < 0.05. IL = interleukin; TNFα = tumor necrosis factor-α.