How long can someone have been dead and then be brought back to life?

It's hard to say. There've been many reports of people whose hearts have stopped beating who later spontaneously regain their vital signs , such as a 34-year-old woman in Spain who was clinically dead for six hours in December 2019. It's thought such cases often occur because an extreme drop in body temperature prevents cell damage that leads to biological and irreversible death.

What criteria do doctors use to confirm someone is dead?

The 1981 Uniform Determination of Death Act (UDDA), accepted by the American Medical Association and the American Bar Association, defines death as sustaining "either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem..." Although the UDDA has been adopted in all 50 states, each state uses it as a baseline only and may have stated exemptions to the definition.

What is the Lazarus syndrome?

A nickname for the phenomenon in which a person who seemingly dies of cardiac arrest spontaneously comes back to life. The clinical term is delayed return of spontaneous circulation (ROSC). It was coined in 1993. There is research to suggest it's an underreported event—in other words, more people have "come back to life" after their heart stops beating than is documented.

Is It Possible to Bring Someone Back From the Dead?

When I tell people that I'm a paramedic, there are usually some follow-up questions. The most common is, "What's the worst call you've ever had?" Another favorite: "Is it possible to bring people back from the dead?" The latter is one of my all-time favorites, and the answer just might surprise you. Yes.

However, there is a catch. The patient can't be too dead. This is a question of survival, not about zombies or chanting at the full moon.

It begins with whether we're discussing clinical death or biological death. Both mean the patient is technically dead, but each term refers to a different level of permanency. One is fixable; the other is not.

cardiac arrest in the rain — Bruce Ayres / Getty Images

Clinical Death

First comes clinical death, which is when breathing and blood flow stop. Clinical death is the same as cardiac arrest; the heart has stopped beating and blood has stopped flowing.

Technically, clinical death requires both the heart and the breathing to stop, but that's just semantics. Breathing and consciousness will cease within a few seconds of the heart stopping.

Clinical death is reversible. Researchers believe there's a window of about four minutes from the moment of cardiac arrest to the development of serious brain damage (as you can probably imagine, that's a pretty hard statistic to validate through a random control trial).

If blood flow can be restored—either by cardiopulmonary resuscitation (CPR) or by getting the heart pumping again—the patient could come back from clinical death. It's not a sure thing; success rates for CPR are pretty dismal.

In a 2010 Johns Hopkins study of patients suffering cardiac arrest somewhere other than a hospital, only 7% of cardiac arrest patients lived long enough to be discharged from the hospital. Those are not good odds for coming back from clinical death.

Before we get too morbid here, it's important to note that the application of CPR and of an automated external defibrillator (AED) increased the chances of survival significantly. All is not lost with clinical death, but you must act quickly.

Biological Death

Biological death, on the other hand, is brain death, and there's no turning back from brain death. That is irreversible death.

Just to make things a bit more complicated, however, it is possible to keep the body alive while the brain is dead. The heart is more of a subcontractor than an employee of the body; it keeps its own hours and works without direct supervision by the brain.

Since the heart works without brain input, it's possible to keep it going for a long time after the brain is dead. Indeed, that's one way that organ donation happens.

There are physical signs of irreversible death that emergency medical responders use to decide whether to attempt CPR on a cardiac arrest victim. The hard truth is: Some people are just plain dead by the time they're found.

Frequently Asked Questions

How long can someone have been dead and then be brought back to life?

It's hard to say. There've been many reports of people whose hearts have stopped beating who later spontaneously regain their vital signs, such as a 34-year-old woman in Spain who was clinically dead for six hours in December 2019. It's thought such cases often occur because an extreme drop in body temperature prevents cell damage that leads to biological and irreversible death.
What criteria do doctors use to confirm someone is dead?

The 1981 Uniform Determination of Death Act (UDDA), accepted by the American Medical Association and the American Bar Association, defines death as sustaining "either (1) irreversible cessation of circulatory and respiratory functions, or (2) irreversible cessation of all functions of the entire brain, including the brain stem..." Although the UDDA has been adopted in all 50 states, each state uses it as a baseline only and may have stated exemptions to the definition.
What is the Lazarus syndrome?

A nickname for the phenomenon in which a person who seemingly dies of cardiac arrest spontaneously comes back to life. The clinical term is delayed return of spontaneous circulation (ROSC). It was coined in 1993.There is research to suggest it's an underreported event—in other words, more people have "come back to life" after their heart stops beating than is documented.

Learn More: What It Means to Be in a Coma

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