why do we have to die?
"the tissues of brain and heart suffer irreversible damage from lack of oxygen. This process was understood to begin after just four or five minutes. If the patient doesn’t receive cardiopulmonary resuscitation within that time, and if his heart can’t be restarted soon thereafter, he is unlikely to recover.
That dogma went unquestioned until researchers actually looked at oxygen-starved heart cells under a microscope.
What they saw amazed them, . "After one hour, we couldn’t see evidence the cells had died. We thought we’d done something wrong." In fact, cells cut off from their blood supply died only hours later.But if the cells are still alive, why can’t doctors revive someone who has been dead for an hour?
Because once the cells have been without oxygen for more than five minutes, they die when their oxygen supply is resumed.
"It looks to us," says Becker, "as if the cellular surveillance mechanism cannot tell the difference between a cancer cell and a cell being reperfused with oxygen. Something throws the switch that makes the cell die."
With this realization came another: that standard emergency-room procedure has it exactly backward. When someone collapses on the street of cardiac arrest, if he’s lucky he will receive immediate CPR, maintaining circulation until he can be revived in the hospital. But the rest will have gone 10 or 15 minutes or more without a heartbeat by the time they reach the emergency department. And then what happens? "We give them oxygen," Becker says. "We jolt the heart with the paddles, we pump in epinephrine to force it to beat, so it’s taking up more oxygen." Blood-starved heart muscle is suddenly flooded with oxygen, precisely the situation that leads to cell death. Instead, Becker says, we should aim to reduce oxygen uptake, slow metabolism and adjust the blood chemistry for gradual and safe reperfusion.
http://www.msnbc.msn.com/id/18368186/site/newsweek/