THE EFFECT OF HYPOVOLEMIC SHOCK AND REPERFUSION ON THE HEPATIC OXYGENSUPPLY-UPTAKE RELATIONSHIP IN THE DOG

The hepatic oxygen supply-uptake relationship was investigated during hypovolemic shock using a right heart bypass technique. The results we re dissimilar to those previously reported in that the ratio of liver oxygen delivery to systemic oxygen delivery was significantly decrease d during shock. The decreased ratio was due to a significant decrease in the portal venous oxygen delivery when compared to the decrease in the systemic oxygen delivery. The decrease in portal venous oxygen del ivery was caused not only by the decrease in portal venous blood flow, but also by the decrease in oxygen content of portal blood. The ratio of hepatic arterial oxygen delivery, on the other hand, was significa ntly increased during shock. Hypovolemic shock increased the liver oxy gen extraction ratio to nearly 100% of the pre-shock value. These find ings suggest a hepatic protective mechanism for matching oxygen uptake to rising hepatic oxygen requirements. Liver oxygen delivery returned to pre-shock value after correction of hypovolemia primarily due to a significant increase in hepatic arterial oxygen delivery. A significa nt negative correlation between the liver oxygen extraction ratio and the oxygen content of hepatic venous blood was observed. The hepatic v enous oxygen content appears to be a simple and appropriate index of l iver oxygenation in clinical medicine because it is difficult to evalu ate the liver oxygen extraction ratio directly.