2 The condition, current treatments and procedure
2.1 Liver transplantation is the treatment of choice for patients with end-stage liver disease. It may also be indicated in patients with some types of primary liver cancer. End-stage liver failure can be either acute (for example, from poisoning) or chronic (for example, because of cirrhosis from alcohol-related liver disease, metabolic, autoimmune or infectious conditions). In children, the most common cause of end-stage liver failure is congenital biliary atresia.
2.2 Limited availability of deceased donor livers for transplantation led to the development of techniques that increase the number of recipients who can benefit from 1 available organ. These include split liver grafts (the larger right lobe is usually grafted into an adult and the left lobe into a child) and reduced (segmental) liver grafts.
2.3 Living-donor liver transplantation is also an option for patients who are deteriorating clinically while waiting for a deceased donor transplant.
2.4 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:
reduce the rate of tissue deterioration that occurs after the liver has been removed from the donor compared with that seen with conventional static cold storage
extend how long the liver can be stored to allow more flexibility in the timing of the transplant operation.
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.
2.5 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.