Does Lowering Donor Body Temperature Improve Organ Transplant Outcomes?

Lowering the body temperature of organ donors in intensive care units before retrieval does not appear to improve how quickly a transplanted organ begins to function, according to a review of four studies current to September 2025. The evidence suggests that therapeutic hypothermia for brain-dead donors does not reduce the time it takes for kidneys, livers, or lungs to start working in recipients.

The review analyzed data from 2,096 donors across studies conducted in the USA and France. Researchers examined whether cooling donors to below a normal core temperature of 35.5°C—a process known as therapeutic hypothermia—could protect organs from the injuries typically caused by brain death and improve outcomes for the people receiving the transplants.

Solid organ transplantation, involving the transfer of a heart, kidney, liver, lung, or pancreas, is the optimal treatment for end-stage organ failure. Because brain death causes significant injury to these organs, medical teams often attempt to optimize donor care to maximize graft function and recipient survival.

Impact of Donor Cooling on Kidney and Lung Function

Data from four studies involving 3,015 recipients indicate that lowering donor body temperature may not reduce the time it takes for transplanted kidneys to start working. Further analysis of three studies involving 2,075 recipients found that cooling made no difference to the survival of the transplanted kidney one year after the procedure.

One study of 526 recipients found that donor cooling did not affect the one-year survival rate of the kidney recipients themselves. Similar results were found for other organs; one study of 99 recipients showed no reduction in the time for transplanted lungs to start working, and a study of 262 recipients found no such reduction for transplanted livers.

Methods and Safety of Therapeutic Hypothermia

Medical teams achieve therapeutic hypothermia using several different methods in the intensive care unit. These include allowing donors to cool spontaneously, using fans, ice packs, or external cooling systems. More invasive methods include bladder irrigation, the use of invasive cooling lines, or temperature-controlled humidified gases during ventilation.

The degree of cooling is categorized into four levels: mild (34.0°C to 35.5°C), moderate (32.0°C to 33.9°C), moderately deep (30.0°C to 31.9°C), and deep (below 30°C).

Regarding safety, the review found that lowering the body temperature of donors is unlikely to reduce the total number of organs available for transplant, based on four studies of 4,265 recipients. Additionally, three studies involving 2,015 donors indicated that this process may not cause heart issues or other complications for the donors.

Evidence Gaps and Study Limitations

The review identified significant limitations in the available data, primarily due to the small number of studies and a heavy focus on kidney transplants over other solid organs.

• One-year survival of the transplanted organ was reported in only three of the four studies.
• No studies reported on the quality of life or the occurrence of heart disease for recipients at the 12-month mark.
• Key organ-specific measures at 12 months, such as heart function or the continued need for insulin in pancreas recipients, were not reported.