Hepatic tissue oxygenation as a predictive indicator of ischemia-reperfusion liver injury

The purpose of this study was to determine whether hepatic tissue oxygenation after ischemia-reperfusion procedures is an indicator for later liver injury. Partial ischemia in the liver was induced by ligating the left pedicles. Rats were divided into two groups according to duration of ischemia: group A (30-min ischemia) and group B (60-min ischemia). Indices of blood oxygenation and blood volume in regional hepatic tissue, serum ALT levels and histological appearance of livers were evaluated. Twenty-four hours after ischemia and reflow, all rats in group A were alive, whereas only 67% survived in group B. Blood-oxygenation index and blood-volume index in group A rats rebounded quickly after reperfusion. In group B, blood-oxygenation index and blood-volume index remained significantly lower than in group A after reperfusion. Serum ALT levels at 60 and 120 min after reperfusion in group B were significantly higher than those in group A. Blood-oxygenation index measured at 5 and 60 min of reperfusion showed significant correlation with serum ALT levels at 120 min of reperfusion. When the percentage recovery of blood-oxygenation index at 5 and 60 min after reperfusion was more than 75%, all rats survived. No obvious signs of hepatocellular degeneration were observed histologically 5 min after reperfusion; however, substantial hepatocellular degeneration had occurred at 120 min of reperfusion in groups A and B. These data indicate that a decline in hepatic tissue oxygenation during the early phase of reperfusion (even when no obvious hepatocellular degeneration has been observed) can be a predictor of subsequent liver injury and prognosis.