Patients can recall near-death experiences up to an hour after being revived by cardiopulmonary resuscitation, a new study has found.
The study has shed new light on the phenomenon of near death experience, researchers say.
For the first time, researchers used brain monitors to identify markers of consciousness and mental activity and reported some patients had clear memories of experiencing death and had brain patterns while unconscious linked to thought and memory.
Writing in Resuscitation, the team from NYU Grossman School of Medicine, USA, who worked with 25 mostly US and British hospitals, say some survivors of cardiac arrest described lucid death experiences while they were seemingly unconscious.
The AWARE-II study (AWAreness during Resuscitation) followed 567 men and women who suffered cardiac arrest during hospital stays between May 2017 and March 2020 in the USA and UK.
Patients were enrolled only if they were hospitalised and given CPR and resuscitation and their brain activity was recorded. A subset of 85 patients received brain monitoring during CPR.
Additional testimony from 126 community survivors of cardiac arrest with self-reported memories was also examined.
Fewer than 10% of the 567 participating patients who received CPR in the hospital, recovered sufficiently to be discharged. However, four in 10 of survivors recalled some degree of consciousness during CPR that was not captured by standard measures.
The study also found that in the subset who received brain monitoring, nearly 40% had brain activity that returned to normal, or nearly normal, from a flatline state.
The study authors hypothesise that the flatlined dying brain removes natural inhibitory systems. This disinhibition may open access to “new dimensions of reality,” including lucid recall of all stored memories from early childhood to death.
While no one knows the evolutionary purpose of this phenomenon, it “opens the door to a systematic exploration of what happens when a person dies,” they say.
Senior study author Sam Parnia, associate professor in the Department of Medicine at NYU Langone Health, said: “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. 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 say the recalled experience surrounding death merits further empirical investigation. They hope to conduct studies that more precisely define biomarkers of clinical consciousness and that monitor the long-term psychological effects of resuscitation after cardiac arrest.
Parnia S, Keshavarx Shirazi T, Patel J et al. AWAreness during REsuscitation – II: A multi-center study of consciousness and awareness in cardiac arrest. Resuscitation. September 2023
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