Extent of ischaemia caused by hepatic vascular exclusion as evaluated in a canine model

1. The difference in the extent of liver ischaemia between a hepatic vascular exclusion model and an inflow occlusion model were investigated by determining Indocyanine Green retention and hepatic mitochondrial redox state during 2 h of ischaemia in 10 mongrel dogs. The splanchnic venous bed and/or the infra-hepatic inferior vena cava were decompressed by pump-driven veno-venous bypass. 2. The Indocyanine Green retention test revealed that there was no hepatic blood flow in the hepatic vascular exclusion model during ischaemia (96.8 +/- 0.73% retention of the dye after 20 min), whereas hepatic blood perfusion was still present significantly in the inflow occlusion model (78.1 +/- 1.19% retention of the dye after 20 min) (P less than 0.01). 3. The mitochondrial redox potential of the liver in the dogs with hepatic vascular exclusion decreased immediately after the induction of ischaemia and remained fixed at extremely low levels. By contrast, in the dogs with inflow occlusion the redox potential decreased gradually after induction and was maintained significantly higher than that in dogs with hepatic vascular exclusion during 2 h of ischaemia (P less than 0.01). 4. It is concluded that the extent of liver ischaemia in the hepatic vascular exclusion model with pump-driven shunt is significantly different from that in the inflow occlusion model with shunt.