Study of cardiac arrest survivors reveals insight into near-death experiences

WASHINGTON: What exactly is happening in the human brain when a person who has almost died is being resuscitated?

A new study of cardiac arrest survivors suggests that almost 40 percent of people undergoing CPR have memories, dreamlike experiences or some type of perception even when they are unconscious. What’s more, brain waves show signs of activity suggesting awareness sometimes up to an hour as they are being brought back to life.

“There’s nothing more extreme than cardiac arrest because they’re literally teetering between life and death, they’re in a deep coma and they don’t respond to us physically at all,” said lead study author Dr. Sam Parnia, an associate professor in the department of medicine at NYU Langone Health. “What we’re able to show is that up to 40 percent of people actually have a perception of having been conscious to some extent.”

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That perception can be just a vague feeling that something is happening around them. However, six patients in the study reported what the researcher called “transcendent recalled experiences of death,” or what many people think of as a near-death experience.

“They may have had a life review, they may have gone to a place that felt like home, and so on,” said Parnia, who is also the director of critical care and resuscitation research at NYU Langone.

Several patients recalled aspects of the medical treatment, such as pain, pressure or hearing doctors. Others remembered dreamlike sensations, such as being chased by the police or being caught in the rain.

Some survivors had positive memories, such as seeing a light, a tunnel or a family member, or feeling intense emotions, such as love, tranquility and peace. Others, however, had a feeling of separation from the body and a recognition that they had died or had delusions of monsters or faceless figures.

In the first-of-its-kind study, published Thursday in the journal Resuscitation, Parnia and colleagues in the US and the United Kingdom monitored 567 people who underwent cardiac arrest resuscitation at 25 hospitals. Fewer than 10 percent of the patients survived, because cardiac arrests are often lethal, even when doctors are standing by to do CPR. The researchers were able to interview 28 of the 53 survivors.

Eleven of them reported having memories or perceptions that suggested at least some consciousness during the resuscitation. The researchers also measured brain oxygen and electrical activity in some patients and found gamma, delta, theta, alpha and beta waves suggesting some mental function during CPR.

“I think that’s incredible,” said Dr. Sheldon Cheskes, a professor of emergency medicine at the University of Toronto, who studies cardiac arrest resuscitation and wasn’t involved in the research. “You would never have known that without being able to do that brainwave monitoring.”