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Surgeons will test extreme hypothermia in trauma patients

Trauma surgeons soon will try plunging some critically injured people into a deep chill — getting their body temperatures as low as 50 degrees — in hopes of saving their lives.

Many trauma patients have injuries that should be fixable but they bleed to death before doctors can patch them up. The new theory: Putting them into extreme hypothermia just might allow them to survive without brain damage for about an hour so surgeons can do their work.

In a high-stakes experiment funded by the Defense Department, the University of Pittsburgh Medical Center is preparing to test that strategy on a handful of trauma victims who are bleeding so badly from gunshots, stab wounds or similar injuries that their hearts stop beating. Just 7 percent of such patients survive.

Get cold enough and "you do okay with no blood for a while," says lead researcher Dr. Samuel Tisherman, a University of Pittsburgh critical care specialist. "We think we can buy time. We think it's better than anything else we have at the moment."

His team plans to begin testing it early next year, but must overcome a hurdle: The law requires that patients consent to be part of medical experiments after they're told the pros and cons. That's impossible when the person is bleeding to death.

So this week, the Pittsburgh team began a campaign required by the Food and Drug Administration to educate residents about the study — with signs on city buses, video on YouTube, a website and town hall meetings next month.

Doctors long have known that cooling can slow the metabolism, meaning organs can go without oxygen for longer periods. Donated organs are chilled to preserve them. And people whose hearts are shocked back into beating often are iced down to about 90 or 91 degrees to help the brain recover.

But traumatic blood loss is another issue. Dropping body temperature to around 50 degrees has worked in dogs and pigs in experiments conducted by Tisherman and others. The animals were sedated and bled until their hearts stopped. Ice-cold fluids were flushed through the body's largest artery, deep-chilling first the brain and heart and then the rest of the body. After more than two hours in this limbo, they were sewn up, gradually warmed and put on a heart-lung machine to restart blood flow. Most survived what should have been a lethal injury and appeared to be cognitively fine.

Tisherman points to rare cases of people who fall through ice, are rewarmed and wake up, as well as deep-chilling that happens during certain heart operations that require completely stopping blood flow briefly.

Dr. Arthur Caplan, a University of Pennsylvania bioethicist who calls the concept promising, says one concern is that some people might survive but with enough brain damage that they'd have preferred death.

"We continue to ignore the 900-pound gorilla of who's going to manage the bad outcome,'' he said.

Surgeons will test extreme hypothermia in trauma patients 11/16/11 [Last modified: Wednesday, November 16, 2011 9:02pm]
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