| Objective: liver transplantation(LT)is a radical method for the treatment of end-stage liver disease.In recent years,the shortage of liver supply is becoming more and more obvious,splitting liver transplantation(SLT)can split a liver into two parts,then be allocated to two recipients,thus improve the utilization rate of liver supply.Ex-vivo liver splitting under the cold preservation may lead to a prolonged ischemia time,and the increasing incidence of primary graft nonfunction(PNF)and complication of biliary.In-vivo liver splitting can reduce the ischemia time,however,it can only be performed in the donation after brain death(DBD)with a stable hemodynamic status.At present,the proportion of liver donation after circulatory death(DCD)is increasing,and the donor source can be further expanded if the DCD liver is able to be performed SLT.But the hemodynamic status of DCD patient is not suitable for in-vivo spliting,and the spliting ex-vivo will bring additional damage to the liver of DCD,which had undergone prolonged ischemia injury.Normothermic machine perfusion(NMP)can maintain the physiological function and metabolism of cells and repair liver damage by continuously providing oxygen and nutrients.This study is intended to establish a simple,stable and practical NMP perfusion preservation system,and to explore the protective effect of NMP on pig SLT.Method: 1.Study of pig liver anatomy: the volume of the liver lobe was measured by anatomical study of the abdomen and liver in 5 pigs,the anatomical distribution of hepatic artery,portal vein,biliary tract and hepatic vein and the selection of liver split line were observed,which provided anatomical basis for SLT.2.Study on SLT without veno-venous bypass of pigs: 20 healthy pigs were divided into two groups,the pre-experimental group which liver was procured according to the literature method,the experimental group which LT was performed using a novel method,and the hemodynamic indexes,postoperative biochemistry,postoperative complications and survival rate were compared,the aim was to master surgical skill and improve survival rate of LT in pig;10 pigs were divided into donor group and receipent group,the donor liver was procured according to the method used in LT experimental group above,and the liver was splited along the median hepatic fissure during the cold preservation process,paying attention to protecting the right middle branch of the portal vein and the right lateral lobe bile duct,the right half liver was used as the graft in SLT without veno-venous bypass,the postoperative complications and survival rate were observed.The aim was to master the surgical techniques of SLT.3.Experimental study of SLT on pig liver from donation after circulatory death using extracorporeal NMP: 5/10 pigs were randomly selected as blood collection,the remaining 5 pigs were established DCD model which had functional warm ischemia 30 minutes and asystolic warm ischemia 10 minutes,DCD liver were perfused and preserved using extracorporeal NMP.The perfusion pressure and perfusate flow of portal vein and hepatic artery were observed,also,the bile production in the process of NMP,the PH value and bicarbonate level of bile were examined,the changes of lactic acid(LAC)、 ALT and AST in perfusate were measured to evaluate graft viability,thus improve the composition of perfusate and NMP protocol.10/30 pigs were randomly selected as blood collection,the remaining 20 pigs were randomly divided into donor groups and recipent groups,each group had 10 pigs.The donor pigs were established DCD model which had functional warm ischemia 30 minutes and asystolic warm ischemia 10 minutes.The recipent pigs were randomly divided into cold preservation group(cold static preservation for 5 hours)and NMP preservation group(cold static preservation for 2 hours,then NMP 3 hours),each group had 5 pigs,SLT was performed in both groups and the right half liver was the the graft.Hemodynamic status,postoperative biochemical,postoperative complications and survival rate were compared between two groups.Results: 1.The liver anatomy of pig was different from that of people,pig had more hepatic artery branch,its portal vein branch of right middle lobe arised from the left trunk of portal vein,and the proportion of bile duct of the caudate lobe and right lateral lobe arised from the left hepatic duct was about 2/3.It was difficult to dissect and separate the inferior vena cava from the caudate lobe,and the left LT needed to reconstruct the graft vessel as recipent inferior vena cava.There were few traffic branchs between the left and right liver in the middle hepatic fissure plane,and the liver could be divided into two half-liver graft with similar volume in the middle hepatic fissure.The novel method used to procure liver and LT without veno-venous bypass were beneficial to the hemodynamic stability,and the incidence of postoperative hemorrhage and hypothermia decreased significantly in experimental group,the survival rate of 7 days in the pre-experimental group was 20%,and 80% in the experimental group.There was no damage of the right middle branch of portal vein and other main vessel during liver splitting at cold static preservation,ALT and AST after SLT were significantly higher than that of LT experimental group,and the survival rate was slightly lower(80% to 60%).The perfusion pressure during NMP maintained controllable and stable by adding a pressure buffer device to the portal vein perfusion pathway,the perfusion mode was controlled rewarming up to normothermia in 20 minutes,the hemodynamics status was stable during NMP,and the perfusate LAC decreased from 6.04±0.54mmol/L at start to 1.96±0.294mmol/L at the end,bile production increased gradually during NMP,bile PH and bile bicarbonate concentration was 7.59±0.04 and 32.98±1.04 mmol/L at the end of NMP respectively.Compared with the cold preservation group,the hemodynamics status of NMP preservation group was more stable after the opening of portal vein flow,and its survival rate of 3 days was 60%,the difference was significant.Conclusion: Pig has its special anatomical characteristics,it is advisable to choose middle hepatic fissure as the liver splitting line when right liver is the graft,and more attention should be paid to prevent the damage of the right middle branch of the portal vein and the right lateral lobe bile duct during liver splitting.The novel method used to perform LT and SLT without veno-venous bypass is practical.The pressure buffer device in portal vein perfusion system can make perfusion hemodynamics more stable.Controlled rewarming up to normothermia in the early stage of NMP,and splitting the liver in the late stage of NMP may add further benefits.Liver vitality can be evaluated by the examination of the perfusate LAC and bile secretion during NMP.The study above show NMP preservation system has a protective effect on DCD pig SLT. |
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