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May 03, 2011

Suspended Animation moving to human clinical trials with Army Funding

Trauma surgeon Dr. Peter Rhee, a former battlefield surgeon for the U.S. military who has been researching suspended animation for 15 years and is a leading innovator in the field.

In the aftermath of the Jan. 8, 2011 Tucson shootings, Dr Rhee and other medical experts asked government officials to support a clinical trial that would test suspended animation on people. A feasibility trial would take place in Baltimore; if successful, trials would expand to five locations around the country, including UMC, which is Southern Arizona's only top-level trauma center.

The Food and Drug Administration already has approved the technique for a human trial. The Army is expected to fund the feasibility phase, and Rhee is lobbying for funding for the full trial.



The technique, that he developed and perfected on research animals while in the military, would work like this: Surgeons inject a patient with a cold, potassium-rich solution used to preserve kidneys for transplant. That puts her in a state of suspended animation, which makes the heart stop and protect her brain.

The cold fluid takes the patient's body temperature down to severe hypothermia - about 50 degrees Fahrenheit - but it has been proven not to not have long-term effects on brain function, Rhee said. The method allows surgeons to work on repairing the patient's injuries for about 60 to 90 minutes while the body is in suspended animation, and the heart during this time is not beating. Medical researchers are trying to figure out ways to make that period last longer.

To that end, researchers are studying the trigger that slows the metabolism in hibernating animals.

There was a 2008 Ted Talk on suspended animation by Mark Roth.



Mark Roth spoke about suspended animation on the PBS Science show NOVA on Jan 20, 2011

Roth thinks that under the right conditions, something triggers cells to slow down their metabolism. It makes them less hungry for oxygen, so they need less of it to survive.

Just what causes that to happen is a mystery. But Roth had an "a-ha" moment while watching TV. Actually, an episode of NOVA.

MARK ROTH: And, in this program, there were people discussing caves where they found that there was a naturally occurring gas that was in the caves. And this gas was hydrogen sulfide.

DAVID LEVIN: It's a toxic gas, but it has a pretty unique effect on the body. One that caught Roth's attention.

MARK ROTH: What happens is that people get exposed to hydrogen sulfide, and they can have what's called a knock-down. It usually takes one breath. And then they collapse to the ground. They appear dead. But you can move them away from that atmosphere, and then they wake up and they're fine. And this is what was so striking to me, because hydrogen sulfide is produced by the cells of our own body.

DAVID LEVIN: That's right. Your own body makes a substance that's poisonous in large doses. It usually only makes tiny, tiny amounts of it. But Roth thought that somehow, if your cells were producing just a little more hydrogen sulfide than normal, they might have enough to slow down their own metabolism if they got stuck in the cold.

MARK ROTH: This could be a molecule that's regulating our oxygen consumption all the time. And maybe, if you had enough of it around, when you got cold, you could actually turn yourself off before you got so cold that you would die. And that's what we see when we watch these people who have these near-death experiences. They appear dead. But they're actually just suspended.

DAVID LEVIN: Roth has tested this theory in the lab. And by giving just a tiny amount of hydrogen sulfide to small mammals, he could induce a hibernation-like state.

MARK ROTH: You put in hydrogen sulfide and dim the metabolism of the animal, and then take away the hydrogen sulfide, and watch the animal come back.

DAVID LEVIN: That ability to control metabolism could be big deal for medicine. If you can make cells need less oxygen, they can survive longer without it. That little difference in time could help save victims of heart attacks or massive blood loss.

MARK ROTH: Initially, we felt that you could use it in the field to literally buy time for people. If it takes a certain amount of time to die, but you slow people's metabolism down so that, for them, effectively time isn't passing so quickly, then they might survive longer as they are trying to get the critical care they need.

DAVID LEVIN: Roth is still researching the effects of hydrogen sulfide in clinical trials. But he says it looks promising. In some instances, even a tiny dose—way smaller than expected—can bump up survival rates without even knocking a patient out.

MARK ROTH: You know, right now, all we're trying to do is just extract benefit with what I'll call short-term exposure to hydrogen sulfide, briefly slowing things down a little bit, or maybe not even much at all, and still getting benefit in critical care situations.

DAVID LEVIN: If the trials are successful, Roth hopes to see hydrogen sulfide used more widely in hospitals within the next few years.

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