“The human brain may have a life review during resuscitation, they may have gone to a place that felt like home, and so on,” mentions one of the researchers.
In the first-of-its-kind study published Thursday in the journal Resuscitation, Parnia and colleagues in the United States and the United Kingdom monitored 567 people who underwent cardiac arrest resuscitation at 25 different hospitals. Fewer than 10% of the patients survived since cardiac arrests are often lethal, even when doctors are standing by to do CPR. The researchers were able to interview 28 of the 53 survivors.
Eleven of them reported having memories or perceptions that suggested at least some consciousness during the resuscitation. The researchers also measured brain oxygen and electrical activity in some patients, and found gamma, delta, theta, alpha and beta waves suggesting some mental function during CPR.
“I think that’s incredible,” said Dr. Sheldon Cheskes, a professor of emergency medicine at the University of Toronto, who studies cardiac arrest resuscitation and wasn’t involved in the research. “You would never have known that without being able to do that brainwave monitoring.”
In cardiac arrest, the heart quivers with uncoordinated contractions, and the blood flow to every part of the body — including the brain — ceases.
Unlike a heart attack, in which the heart continues to beat despite a painful reduction in blood flow, a person in cardiac arrest is always unconscious. CPR is the only way to keep a person alive until the heart is shocked back into a normal rhythm with a defibrillator or an automated external defibrillator or AED. These AED devices can be used by anyone to restart the heart and are often found in public places.
The study was unique in that the researchers also tested if participants could recall specific sights or sounds, known as implicit learning. They placed headphones on the patients during resuscitation and played three words — apple, pear, banana — and also used a tablet to display 10 images.
When asked if they remembered these, only one of the 28 patients who were interviewed correctly remembered the three-word sequence and none could recall the images. The research team also analyzed the recalled memories of 126 other cardiac arrest survivors who sent their experiences by mail or were in a community database.
“They may have had a life review, they may have gone to a place that felt like home, and so on,” said Parnia, who is also the director of critical care and resuscitation research at NYU Langone.
Several patients recalled aspects of the medical treatment, such as pain, pressure or hearing doctors. Others remembered dreamlike sensations, such as being chased by the police or being caught in the rain.
Some survivors had positive memories, such as seeing a light, a tunnel or a family member, or feeling intense emotions, such as love, tranquility and peace. Others, however, had a feeling of separation from the body and a recognition that they had died or had delusions of monsters or faceless figures.
In the first-of-its-kind study published Thursday in the journal Resuscitation, Parnia and colleagues in the United States and the United Kingdom monitored 567 people who underwent cardiac arrest resuscitation at 25 different hospitals. Fewer than 10% of the patients survived since cardiac arrests are often lethal, even when doctors are standing by to do CPR. The researchers were able to interview 28 of the 53 survivors.
Eleven of them reported having memories or perceptions that suggested at least some consciousness during the resuscitation. The researchers also measured brain oxygen and electrical activity in some patients, and found gamma, delta, theta, alpha and beta waves suggesting some mental function during CPR.
“I think that’s incredible,” said Dr. Sheldon Cheskes, a professor of emergency medicine at the University of Toronto, who studies cardiac arrest resuscitation and wasn’t involved in the research. “You would never have known that without being able to do that brainwave monitoring.”
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