Liver transplantation is a complex surgical procedure. It involves removing the liver from a donor and putting it into a recipient. After taking the liver out of the cadaveric donor, it has to be maintained in an optimal condition to continue working well after transplantation. The currently practiced method involves storing the liver over ice to maintain a low temperature. However, this process has a time limitation. It may damage the harvested liver further and may not be sufficient to protect the organ. For this reason, researchers are working hard to find new ways to keep donated liver viable. To address this issue, one of the recently invented methods is perfusion machines, which have shown promising results.
Where are we now?
Traditionally, harvested organs moved for transplantation are kept at a very low temperature by infusing cold solution during the removal of the organ and then storing it over ice. This process is called cold ischemia. Different organs can be kept in cold storage for different lengths before it becomes unusable. For example, a heart’s cold ischemia time is 4–6 hours, while a kidney lasts much longer, for 24–36 hours. The liver can be kept in cold storage between 8 and 12 hours. For successful transplantation, efforts are made to keep cold ischemic time as short as possible.
According to the UNOS (United Network for Organ Sharing), more than 41,000 transplants occurred in 2021 in the United States of America. The liver is the second most commonly transplanted organ after the kidney, worldwide. Unfortunately, the situation in India is not that encouraging. The cadaveric donations are very few. Since most of the transplant centers are situated in big cities, organ donations happen only there. Even if organ donation happens in smaller cities, the transportation of donated organs becomes difficult. If machine perfusion becomes routine, this limitation can be circumvented.
What is a perfusion machine?
Perfusion machines are an alternative method of storing organs outside the body. The machine acts like the body’s heart and lungs, pumping blood like solution and oxygen into the donated organ. Additionally, hormones and nutrients are delivered to imitate what the liver would receive from the intestines and pancreas in a normal living person. It has been recently shown that a perfusion machine can preserve a liver graft for not a few hours, but for several days. This enables the surgeon to perform a liver transplant as an elective surgery rather than an emergency surgery in the middle of the night. It also helps to assess the quality of the liver during the pumping process. A few tests can also be conducted to check if the liver is fit for transplanting. If the unfit liver is transplanted into a recipient and if it does not work well, the patient’s life is in danger and the patient may need to undergo re-transplant under emergency conditions. Machine perfusion is being widely used for kidneys but its use in livers has been highlighted recently.
What’s the future of Machine Perfusion?
Machine perfusion is theoretically suitable for all organs (apart from the liver) although few adjustments have to be made in the technology being used currently. Machine perfusion of organs has an enormous potential to increase the number of organs available for transplants. Many livers are being discarded at present since surgeons are not sure if it’s worth transplanting those livers. If the organ is harvested in a remote area, it can be put on a pump and transported to the transplant center. Machine perfusion can help to identify good livers and the number of unnecessary discards may come down. Researchers may develop therapies like gene therapy in the future so that damaged livers can be repaired and used for transplantation.
But machine perfusion comes with a cost and it should be readily available even in remote places. The machines need to be maintained well. People have to be trained to use them and keep them in usable conditions. The healthcare industry needs to overcome these limitations for machine perfusion to become widely available.
Above article tries to explain machine perfusion to a non-medical personnel. It has been deliberately simplified for those people and should not be equated to Professional medical literature.
