'I saw my entire life': People describe 'death experiences' after cardiac arrest in new study

People undergoing CPR may have consciousness despite the absence of visible external signs of consciousness, a study suggests.

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One survivor remembers people placing the electrodes and then the shock. Another could feel “someone rubbing the bony bit” on his chest.

It’s been assumed that people lose awareness or consciousness soon after their hearts stop beating.

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But in a new study, some cardiac arrest survivors reported having lucid experiences, including a “purposeful review of their lives” while being revived by CPR, even though their brains had “flatlined” and they had no visible external signs of consciousness.

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In some cases, brain activity returned to near normal physiological levels at different points up to an hour into CPR, “suggestive of the emergence of consciousness and resumption of a network-level of cognitive activity,” the researchers report.

They describe their work as the “first report of biomarkers of consciousness during CPR.”

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In all, the study involved 567 patients whose hearts stopped while they were in a hospital. Tragically, only 53 survived to be discharged home and, of those, only 28 were fit and healthy enough to be interviewed. Separately, because so few patients survived, the researchers also analyzed testimony from 126 people who had previously survived a cardiac arrest.

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The aim, said senior study author Dr. Sam Parnia, is to better understand “what’s happening in the brain as people transition from life to death, and while we’re trying to revive them, and to see if we can find any markers of these lucid experiences of death.”

Parnia believes his team may also have found a mechanism to explain seemingly fantastical claims of near-death experiences: the dying brain becomes disinhibited, he said. “Brakes” in the brain that keep us from information overload are removed as the brain is deprived of blood flow and oxygen, “giving people access to dormant pathways of their brain that were otherwise being held down,” said Parnia, a critical care and resuscitation specialist at NYU Langone Health.

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It allows access to deep memories and “hidden dimensions of reality that they would otherwise not be able to access under ordinary circumstances,” he said, an experience that “only comes to the fore in death.”

Millions of people have reported having lucid recalled experiences of death, and nobody understood what was going on in this phenomenon

Since CPR’s discovery 60 years ago, “millions of people have reported having lucid recalled experiences of death, and nobody understood what was going on in this phenomenon,” said Parnia.

Some scientists have been dismissive, assuming they’re merely hallucinations, he said — “a ‘trick of the brain’, that it’s not real.”

It’s also assumed that after about 10 or so minutes of oxygen deprivation, the brain dies. “The brain does not have resilience when it comes to oxygen deprivation,” Parnia said.

However, there’s a difference between losing function immediately, within seconds, and permanently dying, he said.

“We were able to show that, yes, the brain does lose function, it does flatline. But that for even up to an hour after they have been oxygen deprived, and they’re getting resuscitation, that you can see signs of normal brain activity emerge from the flatline state.”

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It’s a dynamic process, he said. The flatlined brain stays flatlined, for a long period of time. But in between it shows spikes of normal activity, “which shows it can mount a normal response. It hasn’t permanently died.”

Some of those patterns are consistent with the ones we have when we’re normally conscious, “like you and I right now,” Parnia said.

Published online Thursday in the journal Resuscitation, the study involved 25 American and British hospitals.

When a “code” for an in-hospital cardiac arrest was called, participating researchers were alerted by pager and rapidly dispatched to the resuscitation room carrying backpacks holding a portable EEG monitor and portable brain oxygen monitor.

Patients were also fitted with wireless headphones, and a tablet computer clamped above their heads.

Researchers had pre-recorded the names of three fruit — apple, pear and banana — on an app installed on the tablet, as well as 10 “visual stimuli,” assorted pictures of people, animals, monuments and newspaper clippings. Only one image remained on the screen until it was switched off at the end of CPR (the researchers didn’t want to make survivors recall multiple images).

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Overall, 365 people had the computer and headphones attached. Roughly 200 also had brain oxygen monitoring, but only 85 had oxygen and EEG monitoring, plus the test of consciousness. It was challenging to get all the equipment into the room without disturbing the CPR efforts, Parnia said.

Of the 567 people who went into cardiac arrest, 53, or nine per cent survived.  Twenty-eight were interviewed. Of those, 11 had memories or perceptions while unconscious during CPR.

Nobody described explicit recall of seeing the images on the tablet, or hearing the “apple, pear, banana” recording. However, when asked to randomly guess what they might have heard, one chose the correct three fruits.

What we realized is that there is a spectrum of consciousness

From the hospital survivors and the first-person testimonies, “What we realized is that there is a spectrum of consciousness,” Parnia said. At one end, vague perceptions, he said, like being aware that someone has come into the room. “At the other end of the spectrum, we have full visual and auditory awareness where people recalled specific details of what was happening to them.”

From a “thematic analysis” they found a common narrative arc, Parnia said. “Those who have a recalled experience of death report the same things: a sense of separation from the body and recognizing they died, a sense that their consciousness continued, a sense that they were reliving their life and evaluating themselves again, a sense that they travelled to a place that felt like home, somewhere they belonged and were returning to, and the sense they realized they had to come back.”

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Those are different from other experiences people have had, he said, like delusions or dreams of “unrelated, haphazard things.”

People reported feeling “as if I was being lifted,” or standing up and seeing their body on the hospital gurney and wondering, “What on earth are those people doing?”

“I saw my entire life in great detail,” one survivor said. “My life and all its events started to play in my mind,” said another.

Parnia had hoped to recruit 1,500 patients, but the study was severely curtailed or stopped across all study sites after COVID hit.

If they’d been able to carry on as planned and recruit more cases, the findings “would have been more concrete,” Parnia said. “At this point we just have to report it as a finding that’s of interest.”

However, if further work confirms the brain doesn’t die within five to 10 minutes of oxygen deprivation, it opens an opportunity to find new ways to restart the heart or prevent brain injuries, he said, and improve “abysmal” survival rates for cardiac arrest.

Parnia first presented his findings at a resuscitation science symposium in November.

National Post

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