Sequential Organ Failure Assessment scores at day 3 by the early development (first 6 hours) of mixed venous-to-arterial carbon dioxide difference. Kruskal–Wallis test, P <0.001. **Significant differences between persistently high mixed venous-to-arterial carbon dioxide difference (Pv-aCO2) and low Pv-aCO2 group; and between persistently high Pv-aCO2 and decreasing Pv-aCO2 group after Bonferroni correction. H-H, Pv-aCO2 high at Time 0 (T0) and 6 hours later (T6); L-H, Pv-aCO2 normal at T0 and high at T6; H-L, Pv-aCO2 high at T0 and normal at T6; and L-L, Pv-aCO2 normal at T0 and T6. SOFA, Sequential Organ Failure Assessment.