LET THE BLOOD FLOW: Blood flow in frostbitten hand before [<i>top</i>] and 30 hours after [<i>bottom</i>] treatment with clot-busting tissue plasminogen activator.
&copy; UNIVERSITY OF UTAH

A blood thinner routinely used to prevent brain damage in strokes dramatically reduced the risk of amputation from severe frostbite in a preliminary study.

Researchers report that only 10 percent of frostbitten toes and fingers had to be amputated in patients who were given tissue plasminogen activator (tPA), an anti-clotting agent, in addition to standard frostbite treatment (rewarming, rehydrating and cleaning the wounded areas); in contrast, 41 percent of frostbitten digits had to be amputated in victims who received only conventional care.

"No substantial improvement in the outcomes of these patients had occurred in decades," says burn surgeon Amalia Cochran of the University of Utah, co-author of a report on the findings published in the June issue of the journal Archives of Surgery. The number of cases of severe frostbite per year has never been tallied, but she says the university burn unit treats about five or six cases a year.

Frostbite kills exposed skin but also damages deeper tissue by restricting blood vessels, preventing oxygen from reaching cells [see image above]. "You've got narrow vessels with thickening fluid trying to get through them," which in effect creates a network of tiny blood clots, Cochran says. "That's the tissue we believe tPA is helping."

Some stroke victims benefit if they receive tPA within a few hours of suffering a stroke, which can be caused by a clot that stops blood flow to part of the brain. Prior studies suggested that tPA benefited frostbite patients as well, but this is the first time its potential was compared with established care alone.

The new study included 32 severe frostbite patients treated in the university's burn unit over the past seven years. Six received tPA along with standard care within 24 hours of their frostbite and 25 received only the customary treatment. One additional patient, who received tPA more than 24 hours after frostbite, did not seem to respond to the drug. Cochran says the only side effect was mild bleeding in one of the six, which stopped when tPA treatment was also halted.

She says the results merit a larger study to discover the best timing and combination of treatments.