HMGB1 and acute respiratory distress syndrome: The alveolar-to-arterial ratio of HMGB1 was lower in ARDS patients than in control at baseline (1 [1–1.3] vs. 1.9 [0.9–10.5], respectively, P = 0.01), on D3 (0.9 [0.9–1] vs. 2.9 [1.4–20.9], P<0.0001) D6 (1 [0.3–1] vs. 3.1 [1.1–16.4], P<0.0001), but not on D0H4 (1.1 [1–1.6] vs. 1.5 [0.9–14.4], P = 0.6).