Tuesday, May 01, 2007
When are you dead?
I stumbled upon this article and my jaw hit the floor. The openning paragraph set the stage:
Consider someone who has just died of a heart attack. His organs are intact, he hasn't lost blood. All that's happened is his heart has stopped beating—the definition of "clinical death"—and his brain has shut down to conserve oxygen. But what has actually died?Interesting question when you think about it. What is death? The religous answer, "When the soul leaves the body." is completely useless in this regard. The obvious scientific answer is that the cells in the body have died. A logical answer and in the case of heart attack victims a wrong answer (at least initally).
What they saw amazed them, according to Dr. Lance Becker, an authority on emergency medicine at the University of Pennsylvania. "After one hour," he says, "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.If conventional wisdom is wrong, then what is the actual cause of death?
Because once the cells have been without oxygen for more than five minutes, they die when their oxygen supply is resumed.At this point I remembered just how bad some science journalists can be so I did a little digging and I found the press release. It started to give actual numbers.
When cells are deprived of oxygen for an hour there is only 4% cell death. After four hours, cell death is only around 16%. Both of these numbers are low. The amazing thing was once we re-introduced oxygen to the cells they died off rapidly to almost 60% cell death.The obvious approach then is to find a way to restart people's hearts that does not include a massive flood of oxygen to the system. The approach they were taking consists of cooling the patient to provide a slower start to their metabolism. Even though this type of treatment is only in its infancy it already has seen a respectable impact:
Immediate cooling cardiac arrest victims increased their survival by 16%. That’s a very significant improvement which could mean thousands of lives saved each year as we get faster and better at cooling patients.The doctors behind the study were not expecting this type of result. Their goals were much less ambitious:
“If I can get a cardiac arrest patient in front of me within five minutes, I have a good chance of saving them,” said Becker. “But the chances of that are slim due to the average response time of Emergency Medical Services, which tend to take between 10-20 minutes to get you to a hospital. The thrust of my work is to take that five minutes and stretch it into 15 minutes.”
