The Lazarus Phenomenon: When Circulation Returns After CPR Stops

Sometimes, minutes after doctors stop CPR and decide it has failed, the heart starts beating again by itself. This is rare, but it is documented. This article explains what researchers know about it.

What is the Lazarus phenomenon?

The return of circulation, without any new treatment, after attempts to restart the heart have been stopped. Doctors call it autoresuscitation. A 2020 scoping review by Les Gordon and colleagues defines it as the return of spontaneous circulation after resuscitation has been tried, judged unsuccessful, and abandoned. It was first formally written up in 1982.

How often does it happen?

Nobody knows, and it is probably under-reported. The 2020 review found more than 60 documented cases from several countries. Lead author Les Gordon said the team suspects it is much more common than the published reports suggest.

One study gives a rough rate. In Helsinki, researchers reviewed out-of-hospital cardiac arrests and found five cases of delayed return of circulation, about six per 1,000 cases. It happened 3 to 8 minutes after CPR stopped. All five patients eventually died.

How long after CPR stops can it happen?

Usually within 10 minutes, but not always. In the 2020 review, circulation returned after five minutes in only about half the cases. Waiting 10 minutes would catch about another 20%. A 2014 systematic review of 49 cases found that the time ranged from several seconds to 33 minutes, and 67.3% of cases occurred within 10 minutes.

What happens to these patients?

Most do not survive in the long run. In the 2014 review, 63.3% of the 49 patients died during the same hospital stay. Only 11, or 22.4%, left the hospital alive with no or only slight damage.

Why does it happen?

It is not known. EMS1 lists several theories. One is air trapping: when rescuers breathe for a patient too fast, air can build up in the lungs and reduce blood returning to the heart. Once the breathing stops, blood flow may recover. Another is that medicines given during CPR take longer than expected to reach the heart. A third is that a blockage in a heart artery shifts after CPR stops. None has been proven.

What do experts recommend?

Watching for a short time before declaring death. Helsinki’s emergency system adopted a 10-minute observation period in 2010, after a malpractice case. The authors of the Helsinki study recommended disconnecting the patient from the ventilator and monitoring for about 10 minutes before pronouncing death. The 2014 review suggested 5 to 10 minutes.

Is this the same as waking up after being declared dead?

No. The Lazarus phenomenon is about circulation returning within minutes after CPR stopped, usually in hospital or emergency care. It is not the same as the old fear of being buried alive. See The Fear of Premature Burial and the Safety Coffin. For how death is confirmed today, see How a Doctor Pronounces Death.

Where can I learn more?

See Clinical Death vs. Biological Death and What Happens to Consciousness During Cardiac Arrest?.