Kidney transplantation could be made more efficient by simply cooling the body of a deceased organ donor by just 2°C from normal body temperature, according to the findings of a new study.

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In the study, researchers found that reducing the temperature of an organ donor to 34-35°C improved the short-term efficiency of kidney transplantation.

The study, published in the New England Journal of Medicine, revealed that inducing a mild state of hypothermia in deceased organ donors reduced the likelihood of delayed graft function – whereby dialysis is required within 7 days of transplantation – in patients receiving kidney transplants by 38%.

At present, around 40% of kidney transplant recipients are reported to experience delayed graft function, which is linked with both increased medical costs and reduced long-term organ function.

“This is a free intervention that can be done at any hospital in the world, and tens of thousands of patients worldwide can benefit from it,” states lead author Dr. Claus Niemann, professor of anesthesia and surgery at the University of California-San Francisco (UCSF).

Dr. Niemann believes their findings could have a major impact on global health and provide significant cost savings in the US through shorter hospital stays, less dialysis and potentially reducing the need for expensive interventions.

“In addition, it may allow us to consider organs we may otherwise reject, especially at the extremes of age, which would result in more patients benefiting from kidney transplantation,” he adds. “This is of critical importance given we have a complete mismatch of transplant need and organ supply in the United States.”

At present, an estimated 101,144 patients are awaiting kidney transplants, according to the US Department of Health and Human Services.

Targeted temperature management, also referred to as therapeutic hypothermia, is already used in the treatment of patients with stroke, asphyxia and certain types of cardiac arrest to preserve the function of the nervous system.

The researchers state that the effect of therapeutic hypothermia on protecting kidney function in transplantation has been uncertain, yet some studies have suggested that mild-to-moderate hypothermia could preserve renal function to some extent.

However, current transplantation protocols stipulate that the bodies of organ donors should be at normal body temperature, often leading to the bodies being actively warmed to ensure this.

Dr. Niemann and colleagues conducted a randomized controlled trial involving a total of 370 organ donors. Of these, 190 were assigned to a group kept at normal body temperature and 180 were assigned to a hypothermia group, the bodies kept at around 2°C lower than the body temperature group.

A total of 572 patients received kidney transplants from the donors in the study – 287 from donors in the body temperature group and 285 from donors in the hypothermia group.

The researchers found that delayed graft function developed in 112 (39%) of patients receiving transplants from the body temperature group, compared with only 79 (28%) of patients receiving transplants from the hypothermia group.

As the intervention was demonstrated to be so successful, an independent data and safety monitoring board recommended an early end to the trial.

In particular, kidneys donated from older donors or donors with health issues that may have compromised their acceptance – also referred to as extended criteria donors – benefited from therapeutic hypothermia.

“From these findings, potentially more organs could be available for transplantation since we can push the limits with these ‘marginal donors,'” explains Dr. Niemann. “This is critical because the number of available deceased organ donors has been stagnant, but the demand has dramatically increased. In the United States alone, about 101,000 patients wait for kidney transplantation.”

In an accompanying editorial, Dr. Ina Jochmans and Dr. Christopher Watson identify some limitations of the study, noting that it does not provide any information on the potential longer-term effects on graft survival or what the effects on other organs are.

However, they state that the study’s results will be welcomed, “not least of all because they have shown that, in this era of high-technology medicine and targeted drug therapy, it is still possible to identify a simple, cheap intervention that can have dramatic therapeutic effects.”

Earlier this month, Medical News Today reported on a mouse study that found the body’s “immune memory” of a rejected transplant may not be a permanent state, suggesting that subsequent transplants can be successful.