Definition of death
The crux of the issue with regard to NRP seems to be variations in how death is defined and the interpretation of those definitions.
DCD donors will have had many tests indicating severe brain damage, a neurologist will have declared the prognosis is futile, and relatives will have agreed to withdraw life support, Dr. Jorde said. “The heart stops beating, and the stand-off time means that blood flow to the brain ceases completely for at least 5 minutes before circulatory death is declared. This is enough on its own to stop brain function.”
Dr. Large made the point that by the time the circulation is reestablished with NRP, more time has elapsed, and the brain will have been without perfusion for much longer than 5 minutes, so it would be “physiologically almost impossible” for there to be any blood flow to the brain.
“Because these brains are already very damaged before life support was removed, the intracranial pressure is high, which will further discourage blood flow to the brain,” he said. Then the donor goes through a period of anoxic heart arrest, up to 16 minutes at a minimum of no blood supply, enough on its own to stop meaningful brain function.
“It’s asking an awful lot to believe that there might be any brain function left,” he said. “And if, on reestablishing the circulation with NRP, there is any blood in the collaterals, the pressure of such flow is so low it won’t enter the brain.”
Dr. Large also pointed out that the fact that the United Kingdom requires a neurologic definition for brain-stem death makes the process easier.
In Australia, St. Vincent’s cardiologist Dr. MacDonald noted that death is defined as the irreversible cessation of circulation, so the NRP procedure is not allowed.
“With NRP, there is an ethical dilemma over whether the patient has legally died or not. Different countries have different ways of defining death. Perhaps society will have to review of the definition of death,” he suggested. Death is a process, “but for organ donation, we have to choose a moment in time of that process that satisfies everyone – when there is no prospect of recovery of the donor but the organs can still be utilized without harming the donor.”
Dr. MacDonald said the field is in transition. “I don’t want to argue that one technique is better than the other; I think it’s good to have access to both techniques. Anything that will increase the number of transplants we can do is a good thing.”
Collaborative decision
Everyone seems to agree that there should be an effort to try to define death in a uniform way worldwide, and that international, national and local regulations are aligned with each other.
Dr. Jorde said: “It is of critical importance that local guidelines are streamlined, firstly in any one given country and then globally, and these things must be discussed transparently within society with all stakeholders – doctors, patients, citizens.”
Dr. Peled, from Providence St. Jude in California, concurred: “There is the possibility that we could change the definition of death, but that cannot be a decision based solely on transplant organizations. It has to be a collaborative decision with a large input from groups who do not have an interest in the procurement of organs.”
He added: “The dialogue so far has been civil, and everybody is trying to do the right thing. My hope is that as a civilized society we will figure out a way forward. At present, there is significant controversy about NRP, and families need to know that. My main concern is that if there is any lack of transparency in getting informed consent, then this risks people losing trust in the donation system.”
Dr. Moazami, from NYU Langone, said the controversy has cast a cloud over the practice of NRP throughout the world. “We need to get it sorted out.”
He said he believes the way forward is to settle the question of whether there is any meaningful blood flow to the brain with the NRP technique.
“This is where the research has to focus. I believe this concern is hypothetical, but I am happy to do the studies to confirm that. Then, the issue should come to a rest. I think that is the right way forward – to do the studies rather than enforcing a moratorium on the practice because of a hypothetical concern.”
These studies on blood flow to the brain are now getting started in both the United Kingdom and the United States.
The U.K. study is being run by Antonio Rubino, MD, consultant in cardiothoracic anesthesia and intensive care at Papworth Hospital NHS Foundation and clinical lead, organ donation. Dr. Rubino explained that the study will assess cerebral blood flow using CT angiography of the brain. “We hypothesize that this will provide evidence to indicate that brain blood flow is not present during NRP and promote trust in the use of NRP in routine practice,” he said.
Dr. Large said: “Rather than having these tortured arguments, we will do the measurements. For the sake of society in this situation, I think it’s good to stop and take a breath. We must measure this, and we are doing just that.”
If there is any blood flow at all, Dr. Large said they will then have to seek expert guidance. “Say we find there is 50 mL of blood flow and normal blood flow is 1,500 mL/min. We will need expert guidance on whether it is remotely possible to be sentient on that. I would say it would be extraordinarily unlikely.”
Dr. Berman summarized the situation: “DCD is increasing the availability of hearts for transplant. This is saving lives, reducing the number of patients on the waiting list, and reducing hospital stays for patients unable to leave the hospital without a transplant. It is definitely here to stay. It is crucial that it gets funded properly, and it is also crucial that we resolve the NRP ethical issues as soon as possible.”
He is hopeful that some of these issues will be resolved this year.
Dr. MacDonald reported he has received “in-kind” support from Transmedics through provision of research modules for preclinical research studies. Dr. D’Alessandro reported he is on the speakers bureau for Abiomed, not relevant to this article. No other relevant disclosures were reported.
A version of this article first appeared on Medscape.com.