Fig. 3. Levels of interleukin 6 (IL-6) were measured by enzyme-linked immunosorbent assay in tracheal lavage fluid. Data are presented as median (pg/ml) with 25th–75th percentiles (  boxes ) and 5th–95th percentiles (  whiskers ). **  P < 0.01 compared with time 0 by Friedman and Wilcoxon test.