An about-face: livers to be transplanted should not be kept cold, as has been done for many years, but warm, at a temperature of 37 degrees. The damage which is done by keeping the organ at a body temperature is in fact minor to that caused by cold temperatures. The findings, by a team at Oxford University in Great Britain, are valid if the liver is treated in a specific way with a machine called Metra provided by the OrganOx company, which was developed by the same researchers.
The English surgeons have just published the results of a controlled experiment in Nature which was performed on 220 patients all over Europe who had undergone a liver transplant, with a portion using organs kept at 37 degrees and others using cold-preserved livers. The results demonstrated that the patients who received the Metra-treated livers, preserved at 37 degrees, showed a 50% decrease in hepatic enzyme levels than those patients with livers handled in the conventional way. The enzyme levels test is the indicator used to determine cellular damage. The patients also had a 10% lower rate of premature dysfunction of the transplanted organ, a dangerous complication which can compromise the whole procedure, compared to 30% of those who received an ice-stored liver. In addition, the surgeons who attempted the procedure using ice-stored livers discarded twice the number of organs compared to the others, and were able to maintain the livers for 8 hours instead of 12, both relevant differences.
As this data was gathered on only 220 patients over the course of a year, time will be necessary to see the long-term effects on transplanted livers, but the preliminary results are encouraging.
The Metra treatment provides the liver with oxygenated blood, nutrients and anticlotting drugs, and removes elements from the immune system which could damage the organ. This instrument is already in use at several European centers and approval is underway in the United States. It is presently not routinely used due to its increased cost, as each Metra-assisted transplant costs an extra 4,000 to 7,000 British pounds (approx. 5,400 to 9,500 Swiss francs) more than those with conventional ice storage. According to the authors of the study, at the moment Metra will be used in more delicate and high-risk transplants, though it is thought it will be more commonly used in the future.