Hugh Pickens DOT Com writes "It was once thought that after the heart stops pumping blood throughout the body, a person has only few minutes before suffering permanent brain damage caused by lack of oxygen and nutrients getting to the brain cells. Now Discovery Magazine reports that developments in the science of resuscitation have made it possible to revive people even hours after their heart has stopped beating and they are declared dead. "Historically, when a person's heart stopped and they stopped breathing, for all intents and purposes, they were dead," says Dr. Sam Parnia adding that this process "could take hours of time, and we could potentially reverse that." Some insights for how to halt the dying process come from case reports of people who were brought back to life with little or no brain damage after hours of a silenced brain and heart. Studies have found that hypothermia seems to protect the brain by decreasing its need for oxygen and aborting activated cell death pathways. Still, there are limits — although body-cooling techniques have improved recovery in many patients after cardiac arrest, there will be a moment when the damage is too much and it's too late to come back. "When somebody's been without oxygen, we know there’s a whole bunch of signals that are now starting to tell cells that it's time to die. So we have an opportunity to modify that programing just a little bit, to say 'wait put the brakes on,'" says Dr. Lance Becker. However, Dr. Stephan Mayer argues that our knowledge of brain damage and dying is incomplete, and it's not always clear how much injury one has endured, and whether it's reversible. "What we've come to learn is that those notions of irreversibility of brain damage are dead wrong," Mayer said. "If you make those judgments too soon without going fully all the way, you may be actually writing people off.""