Almost half of people who survived resuscitation for cardiac arrest had some memory from during the experience despite being deemed clinically unconscious at the time, according to a new study that sheds light on why such patients often exhibit psychological side-effects afterwards.
About nine per cent of patients in the study also said they had near-death experiences while being resuscitated, while two patients said they were aware of what was going on in the room and could "see" and "hear" the medical personnel struggling to save their lives.
British scientists at the University of Southampton spent four years examining 2,060 cardiac arrest cases at 15 hospitals in the U.K., U.S. and Austria. Of those cases, 330 of the patients survived their heart stopping, and 101 completed intensive interviews about their experiences.
Sam Parnia, now an assistant professor of critical care medicine and director of resuscitation research at the State University of New York at Stony Brook, and his team reported in Tuesday’s online issue of the journal Resuscitation that:
- 46 per cent of those interviewed had memories from during their experience, with themes such as fear, bright light, animals or plants, déjà vu, violence or persecution.
- 9 per cent reported having near-death experiences.
- 2 per cent described awareness with recall of "seeing" or "hearing" actual events between the time they were clinically dead and before their hearts restarted.
One man spoke of leaving his body entirely and watching his resuscitation from the corner of the room:
"At the beginning, I think, I heard the nurse say 'dial 444 cardiac arrest.' I felt scared. I was on the ceiling looking down. I saw a nurse that I did not know beforehand who I saw after the event. I could see my body and saw everything at once. I saw my blood pressure being taken whilst the doctor was putting something down my throat. I saw a nurse pumping on my chest," he recalled to the researchers.
As part of the experiment, researchers placed objects such as nationalistic symbols and newspaper headlines on shelves in areas of the hospital where cardiac resuscitation was likely to occur, such as the emergency department. The image was only visible from above the shelf, to ensure that any patients who claimed they saw it did not do so from their hospital bed.
None of the patients in the study said they saw images from the shelves.
However, one patient who said he had a near-death experience gave an accurate depiction of the people, sounds and activities going on around him while he was being resuscitated.
Jimo Borjigin, an associate professor of neurology and physiology at the University of Michigan, has studied how rats show a spike in brain activity when starved of oxygen and are near death.
Borjigin said that may account for the vivid memories, the mental images, the sounds and smells people recall after surviving a near-death experience.
And those memories and images might account for the side-effects like post-traumatic stress disorder, memory loss and depression that sometimes follow a successful resuscitation.
For people researching near-death experiences, there’s little doubt that events do happen at those critical moments in the human brain, Borjigin said. She added that questions remain about where exactly it happens and whether that accounts for consciousness independent of the brain.