A groundbreaking study into near-death experiences has shed new light on what is experienced by cardiac arrest sufferers.
In theory, someone in cardiac arrest is never conscious, but on the verge of life and death, yet this study seemed to suggest otherwise.
It was found that 40% of people who underwent CPR and survived cardiac arrest had memories, dreamlike experiences or some perception even when they were unconscious.
Scientists suggested that certain people were aware of what was happening, finding signs of brain wave activity, sometimes up to an hour, before they were resuscitated.
Lead study author and an associate professor in the department of medicine at NYU Langone Health, Dr Sam Parnia, told NBC News, Sky News’ US partner :”There is nothing more extreme than cardiac arrest because they are literally teetering between life and death, they are in a deep coma and they don’t respond to us physically at all,”
“What we are able to show is that up to 40% of people actually have a perception of having been conscious to some extent.”
6 patients in the study reported what the researcher called “transcendent recalled experiences of death” – what many think of as a near-death experience.
Dr Parnia said they may have had a life review, they may have gone to a place that felt like home, and so on.
Sky News reports that several patients were able to recall aspects of their medical treatment, such as pain, pressure or hearing the voices of doctors.
Others remembered dreamlike sensations, such as being caught in the rain or being chased by the police.
Some had memories that were positive such as seeing a light, a tunnel or a family member, while others felt intense emotions such as love, tranquility and peace.
Others however, had a feeling of separation from the body and a recognition they had died or had delusions of faceless figures or monsters.
The study, that was published in the journal Resuscitation, monitored 567 people who underwent cardiac arrest resuscitation at 25 different hospitals.
Fewer than 10% of patients survived and the researchers were able to interview 28 of the 5Sam3 survivors.
“I think that’s incredible”
11 reported said they could recall or have perceptions of being awake, which suggested at least some consciousness during resuscitation.
Researchers also measured electrical activity and brain oxygen in some patients and discovered certain brainwave activity, suggesting some mental function during CPR.
Dr Sheldon Cheskes, a professor of emergency medicine at the University of Toronto, who studies cardiac arrest resuscitation and was not involved in the research, told NBC said ” I think that is incredible. You would never have known that without being able to do that brainwave monitoring.”
The heart quivers with uncoordinated contractions and flow around the body, including to the brain, ceases during cardiac arrest. Unlike a heart attack, a person in cardiac arrest is always unconscious.
The researchers also tested whether patients could recall specific sights or sounds, known as implicit learning. They placed headphones on patients during resuscitation and played three words: apple, pear, banana while using a tablet to display 10 images.
Only one of the 28 patients interviewed remembered the three-word sequence correctly, and none could recall the images.
An assistant professor of medicine at Harvard Medical School and chair of the writing group for the 2025 American Heart Association post-cardiac arrest care guidelines, Dr Katherine Berg, told NBC the main takeaway was that survivors may retain some memories of CPR.
She hoped that studies said, like this would prompt physicians to ask cardiac arrest survivors about these memories and experiences and assess for any post-traumatic stress or other psychological symptoms that might need to be addressed,” she said.
