Transplant: new way of extracting organs divides doctors – 12/02/2023 – Science

A new method for retrieving an organ donor’s heart has sparked debate about the surprisingly thin line between life and death in the hospital setting — and whether there is a possibility that he may still have some vestige of consciousness or feel pain when his organ is removed. removed.

The new procedure, which has divided opinion among major hospitals in New York and elsewhere, was backed by NYU Langone Health at New York University in Manhattan, which says it was the first in the United States to test the new approach. , in 2020. But New York Presbyterian Hospital, which has the largest transplant program in the city, rejected the technique after it was analyzed by an ethics committee.

If widely adopted, the method will significantly increase the number of hearts available for transplantation and save many lives. This is because most donors belong to a restricted category: those who have been declared brain dead, often after suffering a trauma, such as a car accident. But they remain on life support – the heart beats and the blood circulates, carrying oxygen throughout the body – until their organ is recovered by a transplant team.

According to surgeons in the area, the new technique considerably expands the potential group of donors, including patients in a coma, but without brain death, whose family chose to turn off life support due to the minimal chances of recovery. After these people’s hearts stop, they are declared dead, but the organ is almost never recovered because it often suffers damage from the lack of oxygen during the dying process. Doctors have discovered that by reestablishing blood flow to the heart after the donor has been declared deceased, it is possible to significantly restore it, making it suitable for transplant.

There are, however, two aspects of this procedure that bother some surgeons and bioethicists.

The first consists of the traditional definition of death: the heart stops beating and blood circulation ceases irreversibly. Because the new procedure involves restarting this blood flow, critics argue that this virtually invalidates the previous declaration of death.

But perhaps this is a minor problem compared to the second issue present in the technique: blocking blood circulation from the revived heart with metal clamps, restricting blood flow to the brain to prevent the possibility of any brain activity recovering – the which some doctors and ethicists note may be an implicit acknowledgment that the donor may not be legally dead.

“This procedure is somewhat disturbing,” said V. Eric Thompson, a senior heart surgeon and transplant specialist, during a panel discussion on the topic at the Yale University School of Medicine.

Legally, there are two legal ways to determine death: circulatory death and cerebral death.

In the second case, when there is a complete and irreversible stop of all brain activities, even if the heart continues to beat, death can now be declared. But the donor in focus for the new method is not the one who suffers brain death, but rather the one in the first category, who is not brain dead. It is possible that the patient may still experience reactions, such as blinking when their eye is touched or gasping if the breathing tube is removed. For him, death is not immediate: it can take 5 to 50 minutes after life support is withdrawn and the doctor declares that circulation has ceased.

According to Nader Moazami, a transplant surgeon who supervised the method for the first time, NYU Langone Hospital performed the new procedure – which uses a cardiopulmonary cardiopulmonary bypass machine – to recover the hearts of almost 30 patients who otherwise would not have been transplanted. Vanderbilt University Medical Center in Nashville, Tennessee, adopted it shortly thereafter, and it has since been performed several times.

A group of doctors, however, vehemently rejected the technique.

The American College of Physicians said that blocking the arteries of the brain to ensure brain death while restoring circulation appears to violate the “deceased donor rule” – a fundamental principle in transplants carried out in the United States, which guarantees that organs cannot be obtained. be the cause of a donor’s death.

Robert Truog, a bioethics expert at the Harvard University School of Medicine who also participated in the roundtable at Yale University last month, said this technique promises to increase the number of heart donors, but he thinks its proponents are downplaying the risks. ethical and legal dilemmas: “I’m a little concerned that there is a kind of intentional manipulation of the public by professionals specializing in transplants.”

The discussion about the procedure — sometimes called normothermic regional perfusion (PRN) — is similar to other previous medical and legal debates related to the definition of death, when death actually occurs and what doctors are allowed to do in these last few minutes.

Some experts even consider the possibility of prosecution: “An ambitious prosecutor might argue vehemently that doctors who follow the PRN protocol intend to render irreversible some brain functions that have not permanently ceased, thereby ensuring the patient’s death,” wrote two transplant experts – Alexandra Glazier, a lawyer who runs an organ donation network in New England, and Alexander Capron, a bioethics expert and professor at the University of Southern California – in an opinion piece published in the American Journal of Transplantation , last year.

Currently, 103,327 people are on the transplant waiting list in the United States, and an average of 17 per day die on the waiting list – the majority waiting for a kidney or liver. Heart transplants are less common – the annual rate is 3,500 – and around 20% die or are removed from the list due to their high level of weakness.

Thanks to advances in science, the shortage of organs available for transplantation may at some point diminish. The solution may lie in obtaining organs from genetically modified pigs or human organs developed in animals – or, who knows, developed entirely in the laboratory. However, until then, donated hearts are needed to increase the number of heart transplants.

TransMedics, a Massachusetts company, sells equipment that supplies oxygenated blood to the heart outside the body – which avoids the ethical debate. When removed, the donor organ is placed in something similar to a plastic container, which circulates blood through it. But using this device can be expensive.

The PRN procedure is more economical. It was performed for the first time in the United States by Moazami’s team, on January 20, 2020, on a 43-year-old donor with terminal liver disease. The accumulation of toxins in his body had led him to a coma.

With the family’s permission, the artificial respirator was turned off. After five minutes, the patient began to have difficulty breathing and, after 14 minutes, his heart stopped.

After ten minutes, Moazami’s team opened the patient’s chest, stopped the blood flow to the brain and began pumping blood around the body using a cardiopulmonary extracorporeal circulation machine – the same one commonly used in heart surgeries.

In the end, the heart started beating on its own again and, after half an hour, the surgeons removed it to be transplanted.