Study suggests know your dead after you die

Driven by ambition and curiosity to learn what lies on the other side of death, five medical students deliberately stop their hearts in order to experience “the afterlife” in the new thriller “Flatliners” (Sony Pictures), which opened in U.S. theaters on Sept. 29.

They quickly discover that there are unexpected and terrible consequences of dallying with death — but not everything they experience after “dying” is in the realm of science fiction. A growing body of research is charting the processes that occur after death, suggesting that human consciousness doesn’t immediately wink out after the heart stops, experts say.

But what really happens in the body and brain in the moments after cardiac arrest?

The terms “cardiac arrest” and “heart attack” are frequently used interchangeably, but they are not identical conditions, according to the American Heart Association (AHA). During a heart attack, a blocked artery prevents blood from reaching a portion of the heart, which can cause that section to die — though the heart continues to beat, the AHA explained.

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During cardiac arrest, the electrical signals driving the heart’s pumping action are disrupted, the heart ceases beating and death shortly follows, the AHA said.

In the vast majority of terminal cases, physicians medically define death based on when the heart no longer beats, said Dr. Sam Parnia, director of critical care and resuscitation research at NYU Langone School of Medicine in New York City.

“Technically speaking, that’s how you get the time of death — it’s all based on the moment when the heart stops,” he told Live Science.

Once that happens, blood no longer circulates to the brain, which means brain function halts “almost instantaneously,” Parnia said. “You lose all your brain stem reflexes — your gag reflex, your pupil reflex, all that is gone.”

 

A trajectory of cell death

The brain’s cerebral cortex — the so-called “thinking part” of the brain — also slows down instantly, and flatlines, meaning that no brainwaves are visible on an electric monitor, within 2 to 20 seconds. This initiates a chain reaction of cellular processes that eventually result in the death of brain cells, but that can take hours after the heart has stopped, Parnia said.

Performing cardiopulmonary resuscitation (CPR) does send some blood to the brain — about 15 percent of what it requires to function normally, according to Parnia. This is enough to slow the brain cells’ death trajectory, but it isn’t enough to kick-start the brain into working again, which is why reflexes don’t resume during CPR, he said.

“If you manage to restart the heart, which is what CPR attempts to do, you’ll gradually start to get the brain functioning again. The longer you’re doing CPR, those brain cell death pathways are still happening — they’re just happening at a slightly slower rate,” he told Live Science.

Recent studies have shown that animals experience a surge in brain activity in the minutes after death. And people in the first phase of death may still experience some form of consciousness, Parnia said. Substantial anecdotal evidence reveals that people whose hearts stopped and then restarted were able to describe accurate, verified accounts of what was going on around them, he added.

“They’ll describe watching doctors and nurses working; they’ll describe having awareness of full conversations, of visual things that were going on, that would otherwise not be known to them,” he explained. According to Parnia, these recollections were then verified by medical and nursing staff who were present at the time and were stunned to hear that their patients, who were technically dead, could remember all those details.