Yale Liver Transplant Program Uses New Technology to Preserve Donor Organs

For decades, the race to transplant a donor liver has been measured not in days, but in hours. A surgeon gets the call—often in the middle of the night. A team assembles, and an operation that might otherwise be carefully planned becomes an urgent sprint against the clock.

Now, new technologies are changing that equation, extending how long donor livers can remain viable, giving surgeons more time to assess organ quality, schedule surgery during daytime hours, and reduce the risk of serious complications. The result: more transplants, better outcomes, and shorter hospital stays for patients.

Two machines—normothermic machine perfusion (NMP) and normothermic regional perfusion (NRP), the latter used in donors who have died from circulatory death—work at different stages of the transplant process. Together they address one of the oldest problems in organ transplantation: keeping a liver alive long enough to give it the best possible chance of success.

“These advances make liver transplant safer, reduce hospital stays, and lead to better outcomes overall,” says Hiroshi Sogawa, MD, MBA, surgical director of the Liver Transplant Program. “When these technologies became available, I had no doubt this was going to become standard of care. I believe the majority of academic medical centers use NMP now.”

After a donor organ is removed, surgeons have a limited window to transplant it before the organ deteriorates. Traditionally, donor organs have been preserved by placing them on ice, a method known as cold storage. While this is simple and effective for short-term preservation, the lack of circulation within the organ can cause damage or what’s known as ischemic injury.

To remain viable, livers need to be transplanted within 12 hours. With normothermic machine perfusion, some studies show that timeline can be as long as 40 to 48 hours, Dr. Sogawa says.

Normothermic machine perfusion—sometimes called NMP or organ perfusion—keeps a donor liver at normal body temperature and supplies it with warm, oxygenated blood while it awaits transplant. Instead of sitting on ice, the organ is placed inside a device roughly the size of a small refrigerator, where a pump, oxygenator, and heating system circulate a blood-based solution through it continuously.

This does more than just buy time. Because the liver remains active during perfusion, doctors can monitor its function before deciding whether to proceed with the transplant.

“What’s great is that you can assess the organ’s viability in real time,” Dr. Sogawa says. “We can draw blood and measure lactate,” a key indicator of how well the liver is processing and removing waste products. By continuously monitoring lactate levels, doctors can spot signs of trouble early and make better decisions about whether to proceed with a transplant.

A healthy liver will also produce bile during NMP, another sign it is functioning well.

This objective data reduces the risk of transplanting an organ that may not perform well after surgery.

While NMP preserves the liver after it has been removed, normothermic regional perfusion (NRP) protects it before retrieval. NRP uses a machine to pump warm, oxygenated blood through a deceased donor’s body shortly after the heart stops—known as circulatory death—to keep the organs healthy.

The process is similar to extracorporeal membrane oxygenation (ECMO) or heart–lung bypass, which use an external pump to maintain blood flow and oxygen delivery during surgery or critical illness.

NRP is used only for donors who have died from circulatory death, not brain death. The distinction matters: In circulatory death, the heart has stopped and organs immediately lose blood flow, making rapid restoration essential. In brain death, the brain has irreversibly stopped functioning but the heart can continue to beat with mechanical support, so organs remain supplied with blood and do not require NRP.

Both NMP and NRP reduce the rate of two serious injuries that can harm the liver during transplant: ischemic perfusion injury and ischemic cholangiopathy.

Ischemic perfusion injury, also known as post-perfusion syndrome, occurs when blood supply returns to an organ or tissue after a period without it. This sudden restoration of oxygen-rich blood to the organ can cause significant cellular and tissue damage.

“Even without machine perfusion, ischemic perfusion injury is common and can result in arrhythmias, or irregular heartbeats,” Dr. Sogawa says.

Ischemic cholangiopathy refers to damage to the bile ducts caused by a lack of blood flow. It is a well-recognized problem in liver transplantation, particularly when the donor died of circulatory death.

“With machine perfusion using NRP and NMP for the liver from a donor who died of circulatory death, the rates of these problems are almost zero,” Dr. Sogawa says.

Yale Medicine transplant surgeons began using NMP in heart transplants at Yale New Haven Hospital Transplant Center in 2023. Dr. Sogawa then introduced its routine use for liver transplant in spring 2025.

The Transplant Center has performed 40 liver transplants in the past year and recently received a center of excellence designation from Optum, a health care services company that works with insurers to identify top-performing transplant programs.

These advances come at a crucial time. In the United States, liver transplant activity reached an all-time high with 12,344 liver transplants in 2025, according to the United Network for Organ Sharing (UNOS). Still, an estimated 13 people die each day waiting for an organ transplant—a reminder that demand still exceeds supply, and that advances in organ preservation matter.