Fig. 3. Myeloperoxidase (MPO; A ) and elastase ( B ) in bronchoalveolar lavage fluid recovered at baseline (t = 0) and after 5 h (t = 5) from patients mechanically ventilated with 6 ml/kg and 10 cm H2O positive end-expiratory pressure (LVT/PEEP; open symbols ) or with 12 ml/kg and zero end-expiratory pressure (HVT/ZEEP; closed symbols ). Horizontal lines represent median values. Wilcoxon signed-rank test: # P < 0.01 versus t = 0. ‡ P < 0.05 versus t = 0. Mann–Whitney U test: † P < 0.01 between groups.