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Blood thinner can save frostbitten digits, study says

June 19, 2007|Amber Dance | Times Staff Writer

Frostbite patients were able to keep more fingers and toes when their treatment included a drug that dissolves blood clots, according to a study published Monday.

Surgeons at the University of Utah health center treated frostbite patients with the clot-busting drug called tissue plasminogen activator, or tPA. Six patients who received tPA kept 90% of affected fingers and toes, and 12 patients treated before the center began using tPA had 41% of their frostbitten digits amputated. The research appears in the June issue of Archives of Surgery.

Frostbite is a common hazard for those who work or play in cold weather and among the homeless. Thousands of U.S. soldiers were permanently hobbled by frostbite injuries in the Korean War, and frostbite remains a concern today for soldiers fighting or training in cold weather.

"There's been essentially no progress in frostbite in 30, 40 years," said Dr. John Twomey, director of the burn center at Hennepin County Medical Center in Minneapolis, who was not involved in the study.

Twomey was among the first to treat frostbite with tPA and other blood thinners in the 1980s. A few doctors have started to use tPA treatment, but the therapy has been slow to catch on.

"This is not clearly established as the standard of care," said Dr. Amalia Cochran, one of the study's authors and a burn surgeon at the University of Utah in Salt Lake City. "In our center, we saw better outcomes for these patients."

Frostbite causes injury in two ways. Ice crystal formation on the skin and in other body tissues destroys the cells, causing the tissues to die. Between the dead and healthy tissue is an intermediate zone that may or may not survive. When that tissue thaws, blood flows sluggishly through the damaged vessels and dangerous clots can form. If the clots block circulation, the tissue dies.

Traditional frostbite therapy includes rewarming the affected body parts, providing fluids and caring for the damaged tissue. It can take weeks or months for doctors to determine what fraction of affected tissue will survive.

Before Twomey's research, physicians had no way to treat blocked blood flow. "When we got a scan that showed no blood flow to the fingers, that was essentially the kiss of death," Twomey said.

The new study supports the idea that tPA breaks down clots and restores blood flow to tissue in the intermediate zone, allowing damaged cells to recover.

"What it does is salvage stuff that's in jeopardy," Cochran said. "It's really an addition to what we currently do for frostbite."

To be effective, tPA must be administered within 24 hours of frostbite injury, according to the study.

"The treatment has to be aggressive, and it has to be early," Twomey said.

But tPA cannot be used for trauma patients or those with blood-clotting disorders because the blood thinner would put them at too high a risk for hemorrhage.

"This is not the Holy Grail of frostbite -- yet," Cochran cautioned. "We feel very strongly that the time has come for a multi-center trial, because no single center accumulates enough patients to really do a large study."

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