Doctors long considered 20 minutes the threshold for survival after a heart stopped beating, depriving the brain of oxygen and causing irreparable damage. It turns out that doctors can now revive people whose hearts have stopped beating for as long as five hours after they've "died."
Dr. Sam Parnia, director of resuscitation research at New York's Stony Brook University, says cardiac arrest doesn't have to be a death sentence. With extended CPR and "cooling therapy," patients can be revived up to five hours after their hearts have stopped.
Parnia, author of the book "Erasing Death," says CPR must be prolonged, at the right rate and force so as not to over-ventilate the patient, with machines executing chest compressions, reports BBC News.
In his book, he explains that after the brain stops receiving a regular supply of oxygen it does not instantly die but goes into a sort of hibernation, a way of fending off its own decay. The process of "waking up" this hibernating brain is itself risky, since oxygen can be toxic at this stage.
Parnia says the best response is to cool patients to just below 90 degrees. "Cooling therapy, the reason it works so well, is that it actually slows down brain cell decay," says Parnia.
In response to the case of Carol Brothers, whose heart was restarted after 45 minutes of CPR, at which point she was cooled and ultimately revived after 5 days in a coma, Parnia says it might be time to rethink our ideas of when we write someone off as dead.
"While 45 minutes is absolutely remarkable and a lot of people would have written her off, we now know there are people who have been brought back, three, four, five hours after they've died and have led remarkably good quality lives."
