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    Are the population and subgroups appropriate and described correctly?

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    Are there any other technologies that should be included in the assessment?

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    Is the place of the technologies in the pathway described appropriately?

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    Are livers typically split at paediatric liver transplant centres?

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Ex-situ machine perfusion devices for deceased donor liver transplants

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5 The technologies

This section describes the properties of the technologies based on information provided to NICE by companies and experts, and publicly available information. NICE has not carried out an independent evaluation of these descriptions.

Ex-situ machine perfusion is intended to preserve the donor liver outside the body. Machine perfusion of the liver is typically performed at hypothermic (4 to 12 °C) or normothermic (37 °C) temperatures. A donor liver can be perfused for several hours (depending on the technology), after which it can be implanted into a recipient in the conventional way.

In this procedure, the donor liver is placed in a perfusion machine, which pumps a specially formulated solution (supplemented with nutrients and metabolic substrates) through the organ's blood vessels and removes waste products. The precise configuration of each technology varies depending on the method of machine perfusion but typically comprises a reservoir, a pump, an oxygenator and a warming or cooling unit. Normothermic machine perfusion requires an oxygen carrier, which may or may not be human red blood cells; hypothermic machine perfusion does not. Normothermic machine perfusion also allows assessment of donor liver viability during preservation.

Ex-situ machine perfusion devices may be initiated prior to implantation at the recipient hospital after static cold storage during transportation. Some ex-situ machine perfusion technologies can also be initiated at the donor hospital and continued during transportation of the organ to the recipient hospital.

Some ex-situ machine perfusion devices can also provide a platform for liver splitting during machine perfusion.

The specific aims of machine perfusion technologies differ depending on the technology, but include:

  • increasing utilisation of donated organs

  • improving clinical outcomes for transplant recipients

  • extending how long the liver can be preserved to allow more flexibility in the timing of the transplant operation, which may allow more day-time operations, provide more time for challenging cases and help address other organ allocation, transport and in-hospital logistical considerations. It may also support improved staff well-being and workforce sustainability.

Sections 5.1 to 5.5 describe the 5 included technologies.

5.1 Liver Assist (XVIVO B.V.)

Liver Assist is an in-hospital system for ex-situ machine perfusion of donor livers prior to transplantation into recipients. The intended patient population is people in need of a liver transplant, both adults and children. There are no known contraindications. The technology consists of two main components: the reusable Liver Assist device (CE marked class IIb) and a single use sterile perfusion set (CE marked class IIa). The donor liver is perfused with either a cold or warm oxygenated perfusion solution and nutrients, depending on the settings. The Liver Assist system is intended for hypothermic perfusion up to 24 hours and normothermic perfusion up to 6 hours. It can also slowly rewarm livers from hypothermia to normothermia (termed 'controlled oxygenated rewarming'). The Liver Assist system may also be used as a platform for liver splitting during machine perfusion. The Liver Assist system is intended to be initiated at the recipient hospital.

Liver Assist is used by several NHS transplant centres.

5.2 metra (OrganOx Ltd)

The metra is a fully automated transportable normothermic ex-situ organ perfusion device intended to support livers from deceased donors aged over 16, for up to 24 hours. ​​​The intended patient population is adults active on the waiting list for liver transplantation, other than those with acute/fulminant liver failure. The donor liver is continuously perfused with oxygenated blood, medications and nutrients at normal body temperature. The metra is a UKCA marked class IIa medical device (CE class IIb). It is used with the metra disposable perfusion set (UKCA class IIa; CE class IIa) and bile salts (UKCA class IIa; CE class III). The metra can be initiated at the donor hospital or on arrival at the recipient hospital.

The metra is currently used in several NHS transplant centres in the UK.

5.3 Organ Care System (OCS) Liver (TransMedics)

OCS Liver is a portable ex-situ normothermic machine perfusion system intended for use with donor livers. The intended patient population is any patient who is eligible for a liver transplant. It maintains the donor liver at normal body temperature in a functioning state with oxygenated and nutrient-enriched, blood-based perfusion solution. The OCS Liver system should not be used for livers with moderate or severe traumatic injury, livers with active bleeding or split livers. The device can be initiated at the donor hospital or on arrival at the recipient hospital. The OCS Liver system consists of 3 main components: the OCS Liver console (CE marked class IIa), OCS Liver perfusion set (CE marked class IIb), and OCS bile salt solution (CE marked class III).

OCS Liver is not currently used in the NHS.

5.4 PerLife (Aferetica Srl)

PerLife is an ex-situ machine perfusion system for abdominal organs that can be configured for use with kidneys or livers. It is intended to be initiated at the recipient hospital. The device works by continuously perfusing the organ with oxygenated perfusion fluid. PerLife is capable of supporting machine perfusion at hypothermic, sub-normothermic, and normothermic temperatures. It can also do controlled oxygenated rewarming. 

PerLife has a CE mark and is currently working towards registration with the MHRA to be available to the NHS.

5.5 VitaSmart Hypothermic Oxygenated Machine Perfusion System (Bridge to Life Ltd)

VitaSmart is a hypothermic oxygenated machine perfusion system intended for ex-situ preservation of abdominal organs (i.e., kidney or liver). The intended population is people in need of a liver or kidney transplant who are on the transplant waiting list. VitaSmart may be used in both children and adults. VitaSmart is not transportable; it is intended to be initiated at the recipient hospital.

The technology consists of a machine unit (CE marked class IIb), disposables (class IIa) and oxygenators (class IIa).

VitaSmart is currently used in several NHS transplant centres in the UK.

5.6 The place of technologies in the care pathway

This assessment will consider the use of ex-situ machine perfusion technologies for the preservation and functional assessment of livers from deceased donors, initiated on arrival at the hospital of the person having the transplant, after the liver has been transported using conventional static cold storage.

Where possible, the assessment will also consider potential changes to the national liver transplantation pathway, in line with proposals by NHS Blood and Transplant, including the use of ex-situ machine perfusion technologies during transportation of donor organs, as applicable.