"Live donation to a pre-transplant machine increases the chances of a successful operation," reports BBC News.
Liver transplantation is a final treatment option for people with end-stage liver disease when other treatments can not help.
Once a liver is removed from the body, it begins to experience progressive damage. This damage can be slowed down by a technique known as static cold storage, where the organ is cooled with special preservative liquid and stored in a refrigerator. However, some damage still occurs, especially if the liver is transported far.
Researchers wanted to evaluate the effectiveness of a new preservation technique called normothermic preservation and compare it to static cold storage. Normothermic preservation involves a machine that pumps oxygenated blood, medicines, and nutrients into the liver at normal body temperature.
There was no significant difference between static cold storage and normothermic preservation in terms of body organ acceptance, patient survival, or bile duct complications. In other words, normothermic preservation did not appear to improve the long-term outcome of transplantation.
However, the normothermic method halved the number of livers that needed to be discarded and was associated with a 50% reduction in transplanted organ damage.
Normothermic conservation may therefore be a promising option to increase the number of transplantable livers, but further research on a larger scale is needed to validate these findings.
Where did the story come from?
The study was led by a team of researchers from Oxford University and funded by the Seventh Framework Program of the European Commission. The study was published in the peer-reviewed journal Nature.
British media coverage was generally accurate, focusing on the ability of normothermic preservation to prevent liver damage before transplantation. The similarity between the preservation methods in terms of patient survival and recipient organ acceptance has been less described.
What kind of research was that?
This was a randomized controlled trial in 7 European transplant centers, which investigated whether method of storage of donor organs prior to transplantation could influence the success of a transplant. In particular, the researchers wanted to compare conventional static cold storage and normothermic preservation.
Randomized controlled trials are useful to compare the effectiveness of a new intervention with an existing intervention. They are particularly good when all other factors can be similar, such as the method of transplantation.
What was research about?
Between June 201
Liver transplant recipients were evaluated daily during the first week after surgery and on day 10, day 30, 6 months and 12 months to determine:
- graft survival
- patient survival
- complications such as bile duct obstruction
The primary outcome was the measurement of the difference between the two groups in the liver enzyme aspartate transaminase (AST) levels, measured within 7 days of transplantation. High AST levels are associated with damage to the transplanted liver.
What were the basic results?
Many other livers were kept alive with the newer method: 32 livers in the cold store had to be discarded before transplantation, compared to 16 in normothermic preservation.
Peak AST was half as high during the first 7 days after transplantation in humans who received a normothermic liver than those who received a cold storage liver (mean ratio 0.5, 95% confidence interval [CI] 0.4 to 0.7).
The graft survival between the two groups was not significantly different. At 1 year, 95% of normothermically preserved livers had survived, compared to 96% of stored in cold stores.
There was also no significant difference in patient survival – 10 individuals died during follow-up and the 1-year survival was 95% in the normothermic group and 96% in the cold storage group. Graft failure was the cause of death in 2 people from the cold storage group and 3 from the normothermic group. Finally, there was no significant difference between the groups in terms of bile duct complications, length of hospital stay, average time in the intensive care unit, or the need for renal replacement therapy.
How did the researchers interpret the results?
They said, "Here we show that in a randomized study of 220 liver transplants compared to conventional static cold stores, normothermic preservation is associated with a 50% lower level of graft injury, measured by hepatocellular enzyme release, despite being 50% lower Organ rejection rate and 54% longer mean preservation time.
"There was no significant difference in biliary complications, graft survival, or patient survival. When translated into clinical practice, these results would have a major impact on liver transplant outcomes and waiting list mortality.
This randomized controlled trial compared two methods of organ preservation prior to liver transplantation
There was no significant difference in transplant survival, patient survival or complications, however, normothermic preservation resulted in half as many livers being discarded However, there were some limitations:
- The sample size was small – a much larger study is needed to confirm the results
- The follow-up was only up 1 year after transplant continued – longer term follow-up would be useful to see if any adverse effects develop further
This study showed that normothermic preservation may be a promising option for organs But as the researchers themselves said Further research is needed on the broader potential of the technology.