Kidneys need to be preserved before transplantation to allow time to match kidney to recipient, to transport and prepare the recipient and kidney, and to implant the kidney. It is important that the kidney is cooled and prepared as quickly as possible to minimise damage caused by warm ischaemia. There are 2 established methods of preservation: cold static storage and hypothermic machine perfusion.
In cold static storage, the kidney is flushed through with a sterile preservation solution and is kept on ice in a box before transplantation. Two preservation solutions are widely used in the NHS for cold storage: Marshall's hypertonic citrate (Soltran, Baxter Healthcare) and Belzer UW (Viaspan, Bristol-Myers Squibb).
Marshall's hypertonic citrate solution has a marketing authorisation for use in the preservation of human kidneys before transplantation. The summary of product characteristics (SPC) states that approximately 2 to 3 litres of solution should be delivered to each kidney and lists no adverse events or contraindications. The cost of 1 litre of Marshall's hypertonic citrate solution is £9.60 (obtained from the Baxter Healthcare e-catalogue, 20 October 2008). It is sold in packs of ten 1-litre bags. Costs may vary in different settings because of negotiated procurement discounts.
Belzer UW storage solution is not classified as a device or a medicine. The manufacturer was advised by the Medicines and Healthcare Products Regulatory Agency that it is therefore not covered by relevant legislation and does not require a marketing authorisation or CE mark. The solution does have a marketing authorisation in some European Union countries and is indicated for the preservation of kidney, liver and pancreas. It is not recommended for continuous machine perfusion. The cost of 1 litre of Belzer UW storage solution is £116 (obtained from the manufacturer, 23 April 2008). It is sold in packs of six 1-litre bags. Costs may vary in different settings because of negotiated procurement discounts.
The submission from the British Transplantation Society indicates that in the UK from 2000 to 2007 about 74% of kidneys from deceased donors were stored with Marshall's hypertonic citrate solution and most of the remainder (23%) with Belzer UW storage solution. For the subset of kidneys from non-heart-beating donors, 42% were stored using Belzer UW storage solution and 48% with Marshall's hypertonic citrate solution.
Machine perfusion systems continuously pump cold preservation solution through the kidney. The solution provides nutrients and sometimes oxygen, carries away toxic metabolites and reduces build-up of lactic acid. In machine perfusion the kidney is attached to the machine via the renal artery. Further surgical preparation of the kidney is then required to make the seal airtight.
The LifePort kidney transporter (Organ Recovery Systems) is a portable machine perfusion system which can perfuse a single kidney and can run without supervision. The system requires a solution to perfuse the kidney; University of Wisconsin machine preservation solution is sold as KPS-1 by Organ Recovery Systems for use with the LifePort kidney transporter. The LifePort kidney transporter is CE marked for the continuous hypothermic machine perfusion of kidneys for preservation, transportation and eventual transplantation into a recipient. The cost of the LifePort kidney transporter is £10,700 (obtained from the manufacturer). They are normally purchased in pairs, one for each kidney. Costs may vary in different settings because of negotiated procurement discounts.
The RM3 renal preservation system is a non-portable system that can perfuse 2 kidneys simultaneously under supervision. It is CE marked for the hypothermic pulsatile perfusion of kidneys. No further information is available.
There are 21 kidney transplant centres in England and Wales, 8 of which use LifePort kidney transporters as well as cold static storage. These centres have non-heart-beating donor programmes. The RM3 system is not used in any centres in the UK. The submission from the British Transplantation Society indicates that in the UK from 2000 to 2007 about 2% of kidneys from deceased donors were stored using machine perfusion (excluding cases where method of storage was not reported). For the subset of kidneys from non-heart-beating donors this increased to 20% (excluding cases where method of storage was not reported). However, the data for the subset may not be accurate because only 50% of records for kidneys from non-heart-beating donors included information on how the kidney was stored.
Transplant arrangements limit the use of machine perfusion. Perfusion systems are the property of individual NHS trusts and have to be returned to the transplant centre that owns the machine. This means that they tend to be used only in the local transplant region, which is not compatible with the national allocation of kidneys from deceased heart-beating donors. Therefore, perfusion systems are used mainly to preserve kidneys from non-heart-beating donors, which are allocated only on a local basis. A recent report from the Department of Health's Organ Donation Taskforce has indicated that the organisation of transplantation services may become national in the future.