What Is Circulatory Death and How Is It Determined?

Circulatory death is a legal and medical determination that a person has died based on the permanent stoppage of blood circulation and breathing, as opposed to a brain-based determination of death. In clinical settings, it is established by confirming that the heart has stopped pumping blood and that this cessation will not reverse on its own or through medical intervention. While the concept sounds straightforward, how clinicians actually confirm it, how long they wait before making the call, and what happens afterward in the context of organ donation are all more contested than most people realize.

How Clinicians Confirm That Circulation Has Stopped

There is no single, universally mandated test for declaring circulatory death. A large study of death determinations in intensive care units found that the most common methods were listening for heart sounds with a stethoscope (used about 82% of the time), watching for a flat arterial blood pressure tracing (77%), and checking for a flat electrocardiogram (73%). In cases where organ donation was being pursued, the tools shifted somewhat: a flat arterial blood pressure tracing was used most often (94%), followed by absent pulse oximetry readings (85%) and absent palpable pulse (77%).¹

The accuracy of these tests varies. A systematic review found that manually feeling for a pulse is less sensitive and less specific than directly measuring arterial pressure inside the body. A flat ECG line, by contrast, is highly specific for death, meaning that when the ECG is truly flat, the person is almost certainly dead, but relying on it may lengthen the time it takes to make the determination. Newer tools like point-of-care ultrasound and near-infrared brain monitoring are being explored, but the evidence for their accuracy remains thin.²

One brain-focused approach looks at pulse pressure, the difference between the high and low points in an arterial pressure wave. Research has shown that brain electrical activity on EEG drops below measurable levels when pulse pressure falls to around 8 millimeters of mercury, which is far below what the brain needs to function. This finding suggests that even before the heart fully stops, the brain may have already lost activity if blood pressure has collapsed far enough.³

The Waiting Period and Why It Exists

After the heart stops and resuscitation efforts end (or are not attempted), clinicians do not immediately declare death. They observe the patient for a set period, sometimes called a “hands-off” or “no-touch” interval. This waiting period exists because of a rare but documented phenomenon: the heart occasionally restarts on its own after resuscitation has been stopped. Researchers call this autoresuscitation, and it is sometimes referred to as the Lazarus phenomenon.

A scoping review of published case reports found that in about 47% of documented instances, signs of life reappeared within five minutes of stopping resuscitation. Another 22% showed signs between six and ten minutes. The median time was five minutes, though the range stretched from near-immediate to over three hours in rare outlier cases.⁴ This is why most protocols require a mandatory observation period of at least five minutes, though the exact length varies by country and institution. Some centers use two minutes, some five, and a handful require up to ten. The five-minute standard is most common in organ donation protocols.

What happens in the brain during this window is relevant. Studies of both humans and animals show that measurable electrical brain activity disappears in less than 30 seconds after circulation stops abruptly. In patients with pre-existing brain injury whose blood pressure drops gradually, brain activity may disappear even before the heart fully stops.⁵ The waiting period, then, is not really about the brain. It is about making sure the heart is not going to restart spontaneously.

Controlled Versus Uncontrolled Circulatory Death

The circumstances under which circulatory death occurs fall into two broad categories, and the distinction matters enormously for what happens next. Controlled circulatory death is by far the more common scenario in organ donation. It happens when a decision has already been made to withdraw life-sustaining treatment, typically in an ICU, because the patient’s condition is considered unsurvivable or further treatment would not serve the patient’s wishes. The treating physician and the family are, in a sense, expecting the death. After treatment is withdrawn, the team monitors the patient and, once the heart stops and the observation period passes, death is declared.⁶

Uncontrolled circulatory death, by contrast, occurs when someone suffers a cardiac arrest unexpectedly and resuscitation fails. This includes people who are dead on arrival at a hospital and those who arrest in or out of the hospital and cannot be revived. Using these donors for transplantation is logistically far more difficult because the time between death and organ preservation is unpredictable. While out-of-hospital cardiac arrest is common across Europe, the rate at which those patients can actually become organ donors remains limited, and programs tend to overestimate the number of suitable candidates.⁷ Only a handful of European countries have active uncontrolled donation programs, with Spain and France being the most established.⁸

What Happens in the Operating Room During Controlled Donation

If a patient who is dying in the ICU has consented (or a family member has consented on their behalf) to organ donation, an elaborate choreography begins before life support is withdrawn. Guidelines from the American Society of Transplant Surgeons describe a “prewithdrawal huddle” in which the surgical team, organ procurement staff, and hospital personnel review a long list of logistics. Where will the withdrawal happen? Will the family be present? When will the family be escorted away before procurement begins? Who is responsible for declaring death? What is the hospital’s mandatory no-touch time? How will vital signs be communicated to the procurement team?⁹

The physician who declares death must be entirely separate from the transplant team. This is a foundational safeguard. Once death is declared and the observation period has elapsed, the procurement team moves quickly because organs begin deteriorating the moment blood flow stops. In protocols that use normothermic regional perfusion, for instance, the cardiac team performs a sternotomy after a five-minute observation period and initiates machine-driven circulation to keep the abdominal and thoracic organs perfused with warm, oxygenated blood.¹⁰

Premortem Interventions and Their Controversies

One of the more uncomfortable aspects of donation after circulatory death is the question of what can be done to the patient before death to protect the organs. The most common example is giving heparin, a blood thinner, before life support is withdrawn. The idea is that preventing blood clots in the organs improves their viability for the recipient. But the practice is controversial because it carries a small risk of causing bleeding in the donor, a person who is still alive at the time of administration.¹¹

A study of US registry data covering thousands of liver transplants found that donors who did not receive premortem heparin had worse graft survival outcomes compared with those who did, suggesting the drug does provide a real benefit to the recipient.¹² Professional guidelines recommend obtaining specific, informed consent from the family before administering any premortem medications or performing invasive procedures like inserting cannulas into blood vessels before death.⁹ The tension is real: these interventions benefit only the future recipient, not the dying patient, and that creates an ethical gray zone even when consent is obtained.

The Dead Donor Rule and Whether DCD Violates It

The dead donor rule is the bedrock ethical principle of transplantation: organ recovery must not cause the donor’s death. A person must be dead before vital organs are removed. In brain death, this is relatively clear-cut since the brain has permanently and completely ceased to function. In circulatory death, the situation is more layered because the heart has stopped but has not been destroyed. Theoretically, if resuscitation were attempted, some hearts could be restarted. The key word in the medical and legal definition, though, is “permanent,” not “irreversible.” Death is declared when the cessation of circulation will not reverse on its own and no attempt to reverse it will be made.

Some bioethicists argue this distinction is too thin and that circulatory death donors are not truly dead at the moment organs are procured. Others counter that the dead donor rule does not require an impossible philosophical certainty about the donor’s status. Instead, it requires confidence that the act of organ recovery is not what causes the death. Since the donor’s death results from the underlying illness and the decision to withdraw treatment, not from the procurement itself, the rule is respected.¹³ The original formulation of the rule, focused on prohibiting killing by and for organ donation, is maintained in current practice because vital organs are procured only after circulation has permanently ceased as a consequence of treatment withdrawal.¹⁴

Normothermic Regional Perfusion and Its Ethical Flashpoints

Normothermic regional perfusion, or NRP, has become one of the most debated techniques in transplant medicine. After a donor is declared dead by circulatory criteria and the observation period is complete, NRP uses a machine to pump warm, oxygenated blood through the donor’s body (or a region of it) to keep organs in good condition before they are removed. The catch is that this looks uncomfortably like restarting circulation, which is the very thing that was used to declare the person dead.

The ethical debate around NRP centers on three challenges. First, does NRP negate the prior declaration of death? If circulatory death is defined by the permanent absence of blood flow, and NRP restores blood flow, has the declaration been undone? Proponents argue that NRP is not natural circulation. It is machine-driven, regional, and would stop the moment the machine is turned off. The donor does not “come back to life” any more than a patient on a heart-lung bypass machine during surgery is alive because of the machine. Second, does NRP cause brain death? Since the blood vessels to the brain are clamped during NRP to prevent any flow to the head, critics argue the procedure is actively inducing brain death. The counterargument is that the person is already legally dead by circulatory criteria, and you cannot cause death in someone who is already dead. Third, could oxygenated blood reach the brain through collateral vessels despite the clamps? A small number of NRP donors have had brain blood flow studied during the procedure, and none showed evidence of flow reaching the brain.¹⁵

A scoping review of the ethical literature found no consensus on whether NRP is ethically permissible, identifying six major areas of debate including compatibility with the dead donor rule, potential for donor harm, consent requirements, and effects on public trust.¹⁶ Despite the controversy, NRP is increasingly used because it yields substantially better organ quality and more transplantable organs per donor.

How DCD Has Changed Heart Transplantation

For decades, hearts could only come from brain-dead donors because the organ was, by definition, still beating at the time of procurement. Circulatory death donors were excluded since their hearts had already stopped and sustained a period without oxygen. Advances in preservation technology have changed that. Both NRP and ex-vivo machine perfusion, where the heart is removed and placed on a device that keeps it warm and beating outside the body, now allow hearts from circulatory death donors to be evaluated and transported.¹⁷

The clinical results have been encouraging. A randomized trial published in the New England Journal of Medicine compared 80 recipients of hearts from circulatory death donors with 86 recipients of hearts from brain-dead donors. Six-month survival was 94% in the circulatory death group and 90% in the brain death group, with no meaningful difference in serious heart-related adverse events.¹⁸ A large single-center comparison found no significant differences in one-year survival, severe graft dysfunction, rejection rates, or coronary artery disease in the transplanted heart at one year.¹⁹ These results are meaningful because thousands of patients die each year waiting for a heart transplant, and DCD has meaningfully expanded the pool of available donor hearts.²⁰

Cost and Organ Yield

DCD procurement is more expensive and logistically complex than procurement from brain-dead donors, but the cost picture depends heavily on the technique used. An analysis of over 43,000 donors in the US transplant registry found that NRP-based DCD donors yielded an average of 3.71 organs per donor, comparable to the 3.70 from brain-dead donors, while the older “super-rapid recovery” technique yielded only 2.45 organs per donor. Despite the upfront costs, the study estimated that roughly 31 organs could be procured via NRP for the cost equivalent of a single organ procured through super-rapid recovery with ex-vivo machine perfusion.²¹

For liver transplantation specifically, modeling studies have found that adding DCD livers to the donor pool reduces overall waitlist deaths enough to make the strategy cost-effective at the system level, even though individual DCD liver transplants tend to cost more than those using brain-dead donor livers.²² The benefit is not equal across all patients, though. A cost-effectiveness analysis found that the sickest patients on the transplant waitlist gain the most from accepting a DCD liver, while patients with lower disease severity may actually fare better staying on the list and waiting for a brain-dead donor liver.²³

Pediatric and Neonatal Circulatory Death Donation

Children can be donors after circulatory death, though it happens much less frequently than in adults. Most children who die in hospitals do so under circumstances that would not permit this type of donation, but many who die after withdrawal of life-sustaining treatment may be eligible to donate some organs.²⁴ Canadian guidelines state that the same principles governing adult donation generally apply to neonates as well, provided that expertise in neonatal end-of-life care is available. Infants with severe, life-limiting brain conditions where brain death testing is impossible are not automatically excluded from consideration as donors.²⁵

The logistical and emotional challenges are amplified in pediatric cases. When a potential donor is a newborn, for example, guidelines recommend considering transfer of the mother alongside the infant to a hospital with an active pediatric DCD program, along with ongoing end-of-life care and financial protections for the family. The ethical themes in pediatric DCD mirror those in adult practice but with the added weight of surrogate decision-making for a child.²⁶

The Family Experience

For families, the period surrounding circulatory death and organ donation is a collision of grief, time pressure, and unfamiliar medical language. A national prospective study of relatives’ experiences found that most felt involved in discussions about withdrawing life support and organ donation, but about 80% perceived that they were being asked to authorize the donation rather than simply being informed of the patient’s wishes. Emotional responses were described as ambivalent, mixing reassurance that something meaningful could come from the death with distress about the process itself.²⁷

Qualitative research on family bereavement after controlled DCD has highlighted that outcomes for the family depend heavily on the quality of communication from the clinical team, the sense that end-of-life care was compassionate and not rushed for the sake of organ procurement, and effective teamwork between ICU staff and procurement coordinators.²⁸ These findings underscore that circulatory death determination in the donation context is not just a clinical act but a moment embedded in a family’s experience of loss.

Public Attitudes Toward Different Types of Donation

How the public feels about donating organs after circulatory death, compared with after brain death, is an area that has received surprisingly little formal study. A recent survey found that about 73% of respondents were willing to donate after brain death and a similar 73% were willing in uncontrolled circulatory death scenarios, while willingness for controlled circulatory death was slightly lower at 67%. Almost all respondents, about 96%, assumed uncontrolled DCD was already standard practice, suggesting that the distinction between controlled and uncontrolled donation is not widely understood by the public. When asked why they would donate, altruism was the most common theme, along with a desire not to waste usable organs and a wish to honor a loved one’s expressed preferences.²⁹ The slightly lower willingness for controlled DCD may reflect discomfort with the deliberate withdrawal of treatment that precedes it, even though the decision to withdraw is entirely independent of donation.