Brain Science

How Do We Know Somebody Is Truly Brain Dead?

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How Do We Know Somebody Is Truly Brain Dead? about undefined
In the last few years it seems like it’s been accepted that somebody is truly dead and beyond hope when they’re “brain dead.” It’s broadly defined as a state when brain activity has apparently ceased, and there’s no hope of restoring it. But research is now beginning to raise some challenging questions on what exactly brain death consists of. The question is more complicated than people think. Complete brain death means the patient can no longer execute even involuntary functions like breathing. On the other hand, a “persistent vegetative state” is not brain death, nor is a coma. And there are intermediate states where some parts of the brain are dead, but not others. Meanwhile, as scientists probe more deeply into what happens to the brain as we near death and “die,” it’s turning out brain cells are more resilient than the experts previously believed possible. It’s starting to look like the near future could be something like a science fiction movie -- medical folks might be able to keep a person’s brain alive even after the rest of the body is gone. . .

Resurrected Brains?

In one of the more intriguing studies, performed at Yale, neuroscientists devised an artificial circulation system that revived structures and functions in the brains of pigs that had been butchered at a USDA food processing facility – in some cases four hours after the pigs had been killed!1 And while the researchers didn’t uncover any evidence suggesting the brain had recovered consciousness, it was found that the brain cells, which had been cut off from oxygen for hours, could still carry on important functions when given artificial support. The investigators say this throws doubt on the idea that our brains are completely and irrevocably damaged by being deprived of oxygen. "The assumptions have always been that after a couple minutes of anoxia, or no oxygen, the brain is 'dead,'" says Stuart Youngner, a professor of bioethics and psychiatry at Case Western Reserve University School of Medicine. "The system used (in this research) begs the question: How long should we try to save people?" Dr. Youngner, who was not directly involved in the study, also notes that sometime in the future people who today would be declared legally dead after blood and oxygen had been cut off from the brain for a long time might, in the future, be resuscitated.2

Life After Death – Sort of

The Yale scientists say that their study used a support system that can keep brains from decomposing after death so that studies can be done on the molecular and cellular processes in living brains. They are using pig brains, which are considered similar to human brains in many ways. Their system involves what they call “BrainEx” – which entails pumping into the brain a mixture of chemicals they call Bex perfusate that acts as a kind of blood substitute. The basic structure of these pig brains, say the researchers, was still intact and their blood vessels still functioned. Plus, the brain cells carried on their functions in the synapses where neurons connect to each other, and immune cells were likewise still carrying out their tasks. But the overall coordinated electric flow that forms brain waves and that is linked to conscious awareness and perception did not take place. So their results were well short of a full revival of brain function.

No Sharp Divide Between Life and Death

What does a study like this mean for the future? Well, as Katharina Busl, a professor of neuroscience at the University of Florida, points out, just keeping brain cells alive – or reviving them – is not the same as keeping a functional brain and conscious person alive. In her words, “[The study] does not show that these brain cells were able to function as a nerve cell network leading to higher brain function such as consciousness or awareness – the features that set us apart as humans.”3 Dr. Busl also says that, as a neurologist specializing in critical care, “My analysis of the study is that it reinforces much of what we already know, that death is a continuum.” In other words, we die in stages. And at some point we may be more dead than alive with no hope of being resuscitated. But this research on pig brains shows that someday a person whose condition might once have been considered hopeless could still be restored to life even if the person’s body has been destroyed. Yeah, I know, it sounds a little scary. But that won’t stop the research.

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