One in five people who survive cardiopulmonary resuscitation (CPR) after cardiac arrest may describe lucid experiences of death that occurred while they were seemingly unconscious and on the brink of death, a new study shows.
Led by researchers at NYU Grossman School of Medicine and elsewhere, the study involved 567 men and women whose hearts stopped beating while hospitalized and who received CPR between May 2017 and March 2020 in the United States and United Kingdom. Despite immediate treatment, fewer than 10% recovered sufficiently to be discharged from hospital.
Survivors reported having unique lucid experiences, including a perception of separation from the body, observing events without pain or distress, and a meaningful evaluation of life, including of their actions, intentions and thoughts toward others. The researchers found these experiences of death to be different from hallucinations, delusions, illusions, dreams or CPR-induced consciousness.
The work also included tests for hidden brain activity. A key finding was the discovery of spikes of brain activity, including so-called gamma, delta, theta, alpha and beta waves up to an hour into CPR.
Some of these brain waves normally occur when people are conscious and performing higher mental functions, including thinking, memory retrieval, and conscious perception.
“These recalled experiences and brain wave changes may be the first signs of the so-called near-death experience, and we have captured them for the first time in a large study,” says Sam Parnia, MD, PhD, the lead study investigator and an intensive care physician, who is also an associate professor in the Department of Medicine at NYU Langone Health, as well as the organization’s director of critical care and resuscitation research.
“Our results offer evidence that while on the brink of death and in a coma, people undergo a unique inner conscious experience, including awareness without distress.”
Identifying measureable electrical signs of lucid and heightened brain activity, together with similar stories of recalled death experiences, suggests that the human sense of self and consciousness, much like other biological body functions, may not stop completely around the time of death, adds Parnia.
As the brain is shutting down, many of its natural braking systems are released. Known as disinhibition, this provides access to the depths of a person’s consciousness, including stored memories, thoughts from early childhood to death, and other aspects of reality.
While no one knows the evolutionary purpose of this phenomenon, it clearly reveals “intriguing questions about human consciousness, even at death,” says Parnia.
The study authors conclude that although studies to date have not been able to absolutely prove the reality or meaning of patients’ experiences and claims of awareness in relation to death, it has been impossible to disclaim them either. They say recalled experience surrounding death now merits further genuine empirical investigation without prejudice.
Some 25 hospitals in the U.S. and U.K. participated in the study, called AWARE II. Only hospitalized patients were enrolled to standardize the CPR and resuscitation methods used after cardiac arrest, as well as the recordings made of brain activity. Additional testimonies from 126 community survivors of cardiac arrest with self-reported memories were also examined in this study to provide greater understanding of the themes related to the recalled experience of death.
Parnia says further research is needed to more precisely define biomarkers of what is considered to be clinical consciousness, the human recalled experience of death, and to monitor the long-term psychological effects of resuscitation after cardiac arrest.
A near-death experience (NDE) can be defined as the reported memory of a range of impressions during a special state of consciousness, including a number of unique elements such as an out-of-body experience, pleasant feelings, seeing a tunnel, a light, deceased relatives or a life review, and a conscious return into the body. Many circumstances are described during which NDEs are reported such as cardiac arrest (clinical death), shock after loss of blood (childbirth), coma caused by traumatic brain injury or stroke, near-drowning (children) or asphyxia; also in serious diseases not immediately life-threatening, during isolation, depression or meditation, or without any obvious reason. Similar experiences to near-death ones can occur during the terminal phase of illness and are called “deathbed visions” or “end-of-life experiences.”
So-called “fear-death” experiences are mainly reported after situations in which death seemed unavoidable like serious traffic or mountaineering accidents and “shared-death” experiences are reported by bystanders at the moment of death of a close relative. The NDE is usually transformational, causing enhanced intuitive sensitivity, profound changes of life-insight and the loss of fear of death.
The content of an NDE and the effects on patients seem similar worldwide, across all cultures and all times. However, the subjective nature and absence of a frame of reference for this ineffable experience lead to individual, cultural, and religious factors determining the vocabulary used to describe and interpret this experience.1
Near-death experiences occur with increasing frequency because of improved survival rates resulting from modern techniques of resuscitation and from new therapies for patients with cerebral trauma. According to a recent random poll in the U.S. and in Germany, about four percent of the total population in the western world have experienced an NDE. 2,3
Thus, about nine million people in the U.S., about two million people in the United Kingdom and about 20 million people in Europe should have had this extraordinary conscious experience. A NDE seems to be a relatively regularly occurring, and, to many physicians, an inexplicable phenomenon and hence an often ignored result of survival in a critical medical situation.
After all, according to current medical knowledge it is impossible to experience consciousness during cardiac arrest or deep coma.
Until quite recently there was no prospective and scientifically designed study to explain the cause and content of an NDE, all studies had been retrospective and very selective with respect to patients. Based on these incomplete retrospective studies, some believed the experience could be caused by physiological changes in the brain as a result of lack of oxygen (cerebral anoxia), other theories encompass a psychological reaction to approaching death, hallucinations, dreams, side effect of drugs, or just false memories.
So properly designed prospective studies in survivors of cardiac arrest are necessary in order to obtain more reliable data to corroborate or refute the existing theories on the cause and content of a NDE. We needed to know if there could be a physiological, pharmacological, psychological or demographic explanation why people experience enhanced consciousness during a period of cardiac arrest.
reference link :https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6179502/
