Fig. 3

Bar graph showing temporal changes of tidal volume (gray bars) in patients with moderate or severe acute respiratory distress syndrome and the proportion of patients with diffuse alveolar damage (DAD) at autopsy examination (black bars) between the first decade at left (1991–1999) and the second decade at right (2000–2010) (i.e., before and after the era of reduction in tidal volumes). From 2000, tidal volumes were significantly reduced (from 699 ± 148 ml to 543 ± 106 ml, p < 0.0001), and this reduction was associated with a parallel reduction in the proportion of patients with DAD (from 56% to 44%, p = 0.03), suggesting that low tidal volumes may attenuate DAD. *p < 0.05, **p < 0.01