Clinical Death vs. Biological Death: How Long Can Someone Be Revived?

When the heart stops, is a person dead? The answer used to be yes. Today it is “not necessarily,” because medicine can sometimes restart the heart. That is why doctors speak of two kinds of death. This article explains the difference and the time limits involved. It is general information, not medical advice. In an emergency, call 911.

What is clinical death?

When the heart and breathing have stopped, but the process may still be reversible. Medical News Today defines clinical death as the absence of a pulse, heartbeat, and breathing. A medical text explains that because of resuscitation techniques, cardiac arrest came to be called clinical death rather than simply death, to reflect the chance of bringing the person back.

What is biological death?

When the damage cannot be undone. Medical News Today describes biological death as the absence of brain activity. The medical text above notes that after a long enough time without circulation, brain damage or later brain death usually results, even if the heart is restarted. For how doctors confirm death, see How Does a Doctor Know Someone Is Dead? and Brain Death vs. Coma.

How much time is there?

Very little. A medical text says that without special treatment after circulation is restarted, full recovery of the brain after more than 3 minutes of clinical death at normal body temperature is rare. It reports that in 1990 the laboratory of resuscitation pioneer Peter Safar made a finding about cooling. Lowering the body temperature by three degrees Celsius after restarting circulation could double the safe window from 5 minutes to 10 minutes. The American Red Cross says survival chances decrease by 10 percent for every minute that CPR and defibrillation are delayed.

How many people survive?

About one in ten. The American Heart Association reports that 2021 U.S. data show 9.1 percent survival to hospital discharge for adults treated by emergency medical services after a cardiac arrest outside the hospital. The Red Cross, citing a national cardiac arrest registry, reports 10.5 percent, and notes that the rate has hovered around 10 percent for 20 years outside hospitals and 21 percent inside them. Survival was much higher when someone saw the collapse: 16.1 percent for witnessed arrests, against 4.3 percent for unwitnessed ones.

Does CPR help?

A great deal. The American Heart Association says that immediate CPR can double or triple the chance of survival. Harvard Health describes a Swedish study of more than 30,000 cardiac arrests outside hospitals, published in the New England Journal of Medicine. In people who received bystander CPR before emergency workers arrived, 30-day survival was 10.5 percent, compared with 4 percent in those who did not. The AHA adds that only about 40 percent of people who have an arrest outside a hospital get immediate help.

What is the Lazarus phenomenon?

A rare event in which the heart restarts on its own after CPR has been stopped. Medical News Today explains that it was first described in the medical literature in 1982 and that at least 38 cases have been reported. In one case it describes, a 66-year-old man was pronounced dead after 17 minutes of resuscitation efforts, and his surgeon felt a pulse 10 minutes later. What causes it is unclear. Theories include a pressure buildup in the chest from CPR and high blood potassium.

Where can I learn more?

See What Does the Brain Experience When We Die? and What Happens to Your Body in the First 24 Hours After You Die?.