The OrganOx metra (OrganOx Limited) is a fully automated transportable normothermic organ perfusion device. It is used for normothermic machine perfusion of livers awaiting transplant to improve organ preservation and reduce the rate of organ discard. The device works by placing the liver in a sterile environment and continuously perfusing the organ with oxygenated blood, medicines and nutrients at normal body temperature to mimic normal physiology. This can be done for up to 24 hours before transplant and aims to minimise liver injury, reducing the number of donor livers discarded. This also means the liver is functional, enabling assessment and evidence-based decisions about whether to transplant. Several alternative preservation devices exist including the Organ Assist Liver Assist (capable of both hypothermic and normothermic perfusion) and the TransMedics Organ Care System Liver System (involving normothermic perfusion).
The OrganOx metra is reported to offer higher-quality organ preservation to standard care, aiming to reduce the number of organs that cannot be transplanted. It can be used for up to 24 hours, prolonging how long an organ can be preserved. It can also objectively test functionality of the organ, which may increase safe use of available donor livers.
People identified as needing a liver transplant are placed on a waiting list for a donor liver. The waiting time for a suitable liver can vary quite a lot: the average waiting time for a liver transplant in the UK is reported to be 3 to 4 months for adults (NHS blood and transplant website).
Standard care for liver transplant involves removing the liver of a donor after brainstem death or circulatory death. A donor liver for transplant is usually preserved using static cold storage. This involves the donor liver being flushed with cold organ preservation solution and placed in a sterile bag in a cold storage icebox, aiming to minimise liver degradation. This is done by a specially trained team before being transferred to the selected hospital for transplant as soon as possible, to minimise ischaemic damage to the organ.
Assessing whether a liver is suitable for transplant is based on the characteristics of the donor before retrieving the organ. It is also based on the appearance of the liver: it is not possible to do a formal functional assessment of the organ after retrieval and as such the function of an organ after transplant is unpredictable.
Currently the use of machine perfusion devices for preservation of livers for transplant is by special arrangement only (NICE interventional procedures guidance on ex-situ machine perfusion for extracorporeal preservation of livers for transplantation). There are several devices on the market offering normothermic and hypothermic machine perfusion. The use of these devices is well recognised in current NHS practice and experts report that the OrganOx metra is used across the NHS in different arrangements.
The following publications have been identified as relevant to this care pathway:
Adults who need liver transplants are usually those with end-stage liver disease. It may also be indicated in patients with some types of primary liver cancer as well as some metabolic disorders. End-stage liver disease can be caused by a number of factors. It 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).
Transplants are done by specialist liver transplant surgeons in 7 adult units across the UK.
The OrganOx metra is for all adults having a liver transplant from deceased donors. It may be used in 'transport mode', which involves continuous normothermic perfusion; or in 'back-to-base mode', which consists of normothermic perfusion on arrival at the hospital of the person having the transplant, after initial static cold storage. These options offer flexibility of use across specialist transplant units. The aim is to improve clinical outcomes for the person having the transplant and to enable otherwise marginal organs to be transplanted safely, increasing the number of livers available for transplant.
The OrganOx metra is available for lease at a cost of £30,000 per year per device. Costs per perfusion also include the cost of disposables (£6,000), staff (£500) and associated medicines and solutions used during the procedure (£1,210). The company reports that the incremental cost of the device compared with current standard care is £9,341 per transplant.
Static cold storage is currently used for donor liver preservation in the NHS. The cost of cold storing organs includes the cost of disposable consumables and the solutions in which organs are stored.
In the UK, 922 liver transplants were done between 1 April 2019 and 31 March 2020 (NHS Blood and Transplant data). The number of transplants has been increasing in recent years and is likely to rise further after the change in law to an 'opt-out' system in 2020 (organ donation law in England, NHS Blood and Transplant).
The company proposes that 9 OrganOx metra devices would support current transplant numbers nationally. The cost of this device would be in addition to current standard care. However, the company claims that the metra may reduce the number of livers that are discarded, helping effective functional assessment of donor livers and increasing transplants. The cost increase with OrganOx also includes the additional operational and post-operative care costs for people having a transplant. Normothermic perfusion may also increase flexibility around transplant surgery, which could allow for better use of resources, in particular, staffing in busy surgical departments.
One economic evaluation was found that related to the cost of the OrganOx metra (Javanbakht et al. 2020). This examined the cost effectiveness of the device including discard rates, renal replacement therapy rates, adverse events, length of stay and 5‑year mortality rates. The evaluation reported that the OrganOx metra costs more and is more effective than static cold storage.
Implementation of the device into the pathway is supported by a training package for device users and surgeons which is provided by the company and included in the purchase. The company also currently provides yearly refresher courses to UK customers free of charge. A trained device operator is needed to monitor the device during perfusion and check the perfusion parameters at regular intervals. This staff member should be appropriately trained for any troubleshooting issues. No changes were identified for the pathway after transplant.