Clot-buster treatment works in frostbite patients

Researchers in the United States have found that when people with frostbite were treated with a clot-busting drug commonly used to treat stroke patients, fewer amputations resulted.

The discovery promises another use for the anti-clotting drug tpa (tissue plasminogen activator) and is also a new treatment for a condition where little has changed regarding its management in 25 years.

Those with frostbite often experience swelling as the frozen skin thaws - blocking tiny blood vessels, and traditional therapy consists of tissue re-warming, prolonged watchful waiting and often delayed amputation.

The researchers from the University of Utah in Salt Lake City, say the addition of tpa helped keep blood flowing to the injured area, averting permanent damage.

Study author Dr. Amalia Cochran says people had fewer amputations and less digit and limb loss as a result of their injury.

The researchers suspect tpa helps reduce the injury caused when the frozen skin is warmed again; inflammation during thawing typically stimulates clotting that blocks small blood vessels, leading to cell death; tpa reverses this clotting and blood flow is restored before permanent damage is done.

Dr. Cochran says although a number of individual medical centers have tried tpa on an isolated basis, there have been few studies of its use.

For the study the researchers examined six severe frostbite patients between 2001 and 2006 who were able to seek treatment within 24 hours of sustaining frostbite and did not have other injuries that would prohibit the use of the clot-busting drug.

It was found that of the patients who received the drug none had a limb amputated, compared with 14 amputations among a comparison group of 26 who got standard care, and only 10 percent of affected fingers and toes were amputated in the drug group compared to 41 percent among those who did not get the drug.

Dr. Cochran says seeing the patients within 24 hours was clearly a point of demarcation.

Lead author Dr. Kevin Bruen says the preservation of limbs, which maximizes patient functional outcome, is perhaps the greatest benefit conferred by the use of tpa in frostbite injury.

The drug is not appropriate for all frostbite victims as many have other injuries involving internal bleeding, which would be worsened by the drug.

Cochran says bleeding is the biggest concern and that does to some extent limit the use of tpa.

Dr. Cochran says more studies at different centers are needed to confirm the findings and to determine if the drug would work differently in patients exposed to extreme cold all at once -- allowing for no intermittent periods of thawing -- compared with those whose injuries were the result of repeated freezing and thawing in less extreme temperatures.

The study is published in the Journal of the American Medical Association's Archives of Surgery.