Difference in hepatic tissue oxygenation between total vascular exclusion and inflow occlusion of the liver and the possible role of hepatic venous blood under liver ischemia.

The difference between total vascular exclusion (TVE) and inflow occlusion (IO) of the liver was assessed by the extent of DNA injury in rats and by hepatic tissue oxygen saturation (SahtO2) in pigs. Moreover, the role of hepatic venous blood under liver ischemia was discussed. Seventy percent of the rat livers were exposed to complete IO (hepatic artery + portal vein) or to TVE (IO + hepatic vein) for 30 or 60 min. DNA strand breaks following blood flow interception were measured using the in situ nick translation technique as an indicator of liver damage. IO/TVE were performed on pigs as well under portosystemic bypass, and the oxygen saturation of the hepatic venous blood (SahvO2) was altered by changing the fraction of inspiratory oxygen or by oxygenating the inferior caval blood using an extracorporeal membrane oxygenator. The changes in SahtO2 were measured sequentially using near-infrared spectroscopy. The results were as follows: (1) DNA injury occurred more severely under TVE than under IO of the rat liver at the end of ischemia, as well as 30 min after revascularization. (2) SahtO2 during TVE was significantly lower than that during IO. (3) The increase in SahvO2 by oxygenation of the inferior caval blood resulted in the elevation of SahtO2 under IO. In conclusion, TVE could cause greater damage to the liver than IO due to the lack of the hepatic venous blood. Hepatic venous blood might play an important role in hepatic tissue oxygenation in the case of hepatic blood flow interception.