A donated human liver has been kept alive, warm and functioning outside a human being on a newly-developed machine and then successfully transplanted into patients in a medical world first.

A British team of doctors, engineers and surgeons announcing the achievement on Friday said it could be common practice in hospitals across the developed world within a few years, up to doubling the number of livers available for transplant.

So far the procedure has been performed on two patients on Britain's liver transplant waiting list and both are making excellent recoveries, the medical team told a news conference.

"We have taken something which used to be very simple technology, placing an organ on ice and around it recreated the environment that it would normally encounter within the human body," said Constantin Coussios, a professor of biomedical engineering at Oxford University and one of the machine's co-inventors.

"A warm preserved organ is very, very different to something stored on ice. It has to be kept warm, it is now breathing and burning sugar just as it would within the body, so it needs to be fed, it needs to be oxygenated, blood needs to be circulated around it," he said.

Currently livers destined for transplant are kept "on ice" in a process which cools them to slow down their metabolism and does not keep them functioning as they would inside a body.

This system has worked for several decades, but can also often lead to livers becoming damaged and rendered unfit for use in patients who need them.

Around 13,000 liver transplants are carried out each year in Europe and the United States, but there is a combined waiting list of around 30,000 patients who need a new liver.

The new technology, developed by Coussios together with Peter Friend, director of the Oxford Transplant Centre, preserves the liver at body temperature and "perfuses" it - supplying it with oxygenated red blood cells to keep it alive

The device can keep a liver functioning normally - just as if in a person, with blood circulating through its capillaries and bile being produced - outside the body for 24 hours or more.

The results from the first two transplants using the new technology, carried out in London last month, suggest the device could be useful for all patients needing liver transplants.

The team now plans to run a pilot trial with 20 more liver transplant patients at KCH. Coussios said successful results of that trial would allow them to apply for marketing authority, meaning the device could be on the market by as early as 2014.

Presented by Adam Justice