Fig 4. Infection disrupts acid-base and oxygenation homeostasis.

Arterial pH (A) progressively declined from baseline (BL) of the end of the experiments but these changes did not reach statistical significance. Similarly, bicarbonate (HCO₃^_) concentration declined over time (B) and the end value was significantly different from BL (*p = 0.02). In accordance with the mechanical ventilation protocol, the (C) positive expiratory pressure (Pet) of CO₂ remained relatively constant. Oxygen consumption (D) was highly variable but trended downward toward the end of the experiments. However, the oxygen partial pressure (PaO₂) to fractional inspired oxygen (FiO₂) ratio (E) continuously declined from BL to 6h (⁺p = 0.005) and 8h (^#p = 0.001). Mixed venous oxygen saturation (SmvO₂) progressively declined (F) from BL to 4h (^{^}p = 0.009), 6h (⁺p = 0.05), 8h (^#p = 0.01) and the end (*p = 0.005) of the experiment. Data are the mean(SE) of five animals. ^{^} Denotes significant difference between baseline and 4h. ⁺ Denotes significant difference between baseline and 6h. ^# Denotes significant difference between baseline and 8h. * Denotes significant difference between baseline and end of experiment.