The procedure of “Ex-situ machine perfusion for extracorporeal preservation of livers for transplantation” is officially credited by the National Institute of Health and Care Excellence in England. This means that the procedure is approved by a dedicated commitee which took the procedure in consideration after clinical results had shown the technique is solid and provides good results without a significant risk for the organ.
The accredited procedure is discribed as follows on the NICE website:
Ex-situ machine perfusion preserves the donor liver outside the body under normothermic or hypothermic conditions. A perfusion machine is used to deliver oxygenated perfusate (which may or may not contain blood depending on the technique employed), supplemented with nutrients and metabolic substrates. The intention is to:
Normothermic machine perfusion also allows assessment of donor liver viability and function during preservation. The aim is to improve clinical outcomes for the recipient and to enable otherwise marginal organs (such as those donated after circulatory death, steatotic livers and livers from older people) to be transplanted safely, so increasing the number of livers available for transplantation.
In this procedure, the donor liver is placed in a perfusion machine. The precise configuration of the machine depends on whether normothermic or hypothermic perfusion is being used. Typically, it comprises a reservoir, a pump, an oxygenator, a warming or cooling unit and, for normothermic machine perfusion only, monitoring equipment. Both the hepatic artery and portal vein of the liver may be perfused. For normothermic perfusion, the effluent perfusate is collected and recirculated through the liver. A donor liver can be perfused for several hours, after which it can be implanted into a recipient in the conventional way.