Survivors of cardiac arrest recall experience of death

In a study led by researchers at the NYU Grossman School of Medicine, some cardiac arrest patients revived by cardiopulmonary resuscitation (CPR) had clear memories of experiencing death and even had brain patterns that were linked to thought and memory while unconscious. Their work has been reported in the journal Resuscitation.

According to the study authors, survivors have long reported having heightened awareness and powerful, lucid experiences — including a perception of separation from the body, observing events without pain or distress, and a meaningful evaluation of their actions and relationships. This new work found these experiences of death to be different from hallucinations, delusions, illusions, dreams or CPR-induced consciousness.

The AWAreness during REsuscitation (AWARE)-II study followed 567 men and women who suffered cardiac arrest during hospital stays between May 2017 and March 2020 in the United States and United Kingdom, with a subset of 85 patients receiving brain monitoring during CPR. Additional testimony from 126 community survivors of cardiac arrest with self-reported memories of death was also examined.

Fewer than 10% of the 567 patients studied, who received immediate CPR in the hospital, recovered sufficiently to be discharged. Four in 10 of patients who survived, however, recalled some degree of consciousness during CPR not captured by standard measures. In those patients who received brain monitoring, nearly 40% had brain activity that returned to normal, or nearly normal, from a ‘flatline’ state, at points even an hour into CPR. As captured by EEG, a technology that records brain activity with electrodes, the patients saw spikes in the gamma, delta, theta, alpha and beta waves associated with higher mental function.

“Although doctors have long thought that the brain suffers permanent damage about 10 minutes after the heart stops supplying it with oxygen, our work found that the brain can show signs of electrical recovery long into ongoing CPR,” said senior study author Sam Parnia, Associate Professor at NYU Langone Health and Director of Critical Care And Resuscitation Research at NYU Langone. “This is the first large study to show that these recollections and brain wave changes may be signs of universal, shared elements of so-called near-death experiences.

“These experiences provide a glimpse into a real yet little-understood dimension of human consciousness that becomes uncovered with death. The findings may also guide the design of new ways to restart the heart or prevent brain injuries and hold implications for transplantation.”

The study authors hypothesise that the flatlined, dying brain removes natural inhibitory (braking) systems. These processes, known collectively as disinhibition, may open access to “new dimensions of reality”, they said, including lucid recall of all stored memories from early childhood to death, evaluated from the perspective of morality. While no one knows the evolutionary purpose of this phenomenon, the authors said it “opens the door to a systematic exploration of what happens when a person dies”.

The authors concluded that research to date has neither proved nor disproved the reality or meaning of patients’ experiences and claims of awareness in relation to death. They say the recalled experience surrounding death merits further empirical investigation and plan to conduct studies that more precisely define biomarkers of clinical consciousness and that monitor the long-term psychological effects of resuscitation after cardiac arrest.

Image caption: The AWARE-II study team practising brain monitoring methods. Image credit: NYU Langone Health.