Experimental Study Of The Optimization Of Liver Portal Triad Blood Inflow Control

Aim Temporary portal triad clamping (Pringle maneuver) during liver resection can reduce intraoperative blood loss, but also correlates with liver ischemia and reperfusion (I/R) injury. In this study different model of hepatic portal blood inflow control was designed, and the safety, effectiveness and applicalbility of the models was evaluated in a rat normothermic liver I/R model.Methods Two hepatic portal blood inflow control methods were established based on the unique dual blood supply of the liver via portal vein (PV) and hepatic artery (HA):(1) One method is continuously clamping the PV while preserving the HA. In this method the caudal lobe of the liver was not clamped and kept as a passage of the portal blood flow in order to reduce the intestinal congestion; (2) The other method is preserving 30% PV flow as by-pass of intestinal blood and the hepatic artery was clamped. These two methods were compared respectively with the classical Pringle method in a rat normothermic liver I/R model. Then the liver I/R injury was assessed by measuring the 7-day survival rate, liver blood loss, safe tolerant time limit of hepatic portal occlusion, liver blood perfusion pressure, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), liver tissue malondialdehyde (MDA), Na+-K+-ATPase and liver histology. The intestine I/R injury was also detected in some experiments.Results Compared with Pringle method, the safe tolerant time limit in group of preserving hepatic artery blood was extended from 90 min to 110 min. However, the liver blood loss was not significantly increased. Preserving hepatic artery in hepatic vascular occlusion also showed lower ALT, AST and MDA values and higher Na+-K+-ATPase activity on the first hour and first day post-reperfusion than Pringle method. Histopathological examination showed less hepatocyte vacuolization, necrosis, sinusoidal congestion and minimal destruction of the lobular architecture.In the group of preserving 30% portal venous flow and clamping the hepatic artery, rats were tolerant to 120 min of hepatic portal occlusion. The 7-day survival rate was 100%. The liver blood loss was not significantly increased compared with Pringle method. Preserving 30% portal venous flow also showed lower ALT, AST and MDA values but higher Na+-K+-ATPase activity on the first hour and first day post-reperfusion than Pringle methods. The score of I/R-induced hepatocyte injury graded with Suzuki’s criteria was also significantly lower than the group with Pringle method.Conclusions These data indicate that continuously clamping the portal vein while preserving the hepatic artery, or continuously clamping the hepatic artery while preserving 30% portal venous flow, did not increase blood loss significantly in a rat liver I/R model, however both of the methods could reduce liver I/R injury compared with Pringle method. Thus, preserving hepatic artery inflow or 30% portal venous flow during portal triad blood inflow control might become an alterative maneuver in liver surgery due to its ability to increase the safe tolerant time limit to normothermic hepatic ischemia.