Increases in oxygen extraction during rapidly fatal septic shock in rats

Oxygen utilization was studied in a lethal model of rat peritonitis. Cecal ligation and perforation induced rapidly fatal septic shock in five animals. Five animals served as sham-operated controls. Arterial pressure, cardiac output, arterial blood lactate concentration, and arterial and central venous blood gases were sequentially measured over a period of 3 hours. In septic animals, systemic oxygen extraction increased from 33% +/- 5% to 70% +/- 5% (P less than 0.01) to maintain total body oxygen consumption. However, arterial lactate level increased from 0.5 +/- 0.1 mmol/L to 4.9 +/- 0.5 mmol/L (P less than 0.01) over the same study interval. Cardiac output was correlated with central venous oxygen desaturation (r = 0.66, P less than 0.001). Central venous oxygen saturation was inversely correlated with lactate concentration (r = -0.87, P less than 0.001). These data suggest that cellular oxygen utilization is largely maintained during rapidly fatal septic shock.