Blood Thinner Rescues Frostbitten Fingers and Toes

Scientific American ^ | June 19, 2007 | JR Minkel

[neverdem]

Clot busting drug reduces number of amputations from severe frostbite

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.

[neverdem]

LET THE BLOOD FLOW: Blood flow in frostbitten hand before [top] and 30 hours after [bottom] treatment with clot-busting tissue plasminogen activator.© UNIVERSITY OF UTAH

The same drug is also used for myocardial infarctions, aka "heart attacks." It's only used in ischemic strokes, not hemorrhagic ones.

[null and void]

ping

[Dr.Zoidberg]

This is very good news for those of us who enjoy our time out in the snow.

I take every precaution I can to prevent frostbite when I’m in the weather, but knowing there’s hope should I get in trouble gives me a little less to worry about.

[Smokin' Joe]

A caution, though, Heparin Scare: Deaths from Tainted Blood-Thinner Spur Race for Safe Replacement

Thanks, nully!

[null and void]

tPA should be safe, for now. It doesn’t come from China. Yet...

[fortunecookie]

Wow. That is good news.

[diogenes ghost]

Kudos for posting a REAL article, damned refreshing to so something that’s not a vanity.

[60Gunner]

tPA is not used for heart attacks; it is used for ischemic strokes, and only if the last time the patient was seen without symptoms is less than three hours. After that, tPA is useless because the damage is pretty much done.

A different anticoagulant is used for MIs. Integrilin is the standard anticoagulant for heart attacks per current best practice guidelines.

[Criminal Number 18F]

This is amazing. Cold weather injuries were a very common problem in my little world in the 80s and 90s. Usually we could get somebody help before the digits froze solid, but once that happened, damage was irreversible and the only treatment was amputation.

Not being radical enough on the amputation led to successive amputations, chasing gangrene towards the torso, and in one case, death.

Have to look into this stuff. Is it something we can put in a field medic’s aid bag, or does it have handling/refrigeration/shelf life issues?

Was warfarin/coumadin therapy ever tried for frostbite?

d.o.l.

Criminal Number 18F

[neverdem]

Have to look into this stuff. Is it something we can put in a field medic’s aid bag, or does it have handling/refrigeration/shelf life issues?

Was warfarin/coumadin therapy ever tried for frostbite?

Both questions, I don't know.

When I have to read about drugs, I read American Hospital Formulary Service® Drug Information AHFSDI, and Drugs: Facts and Comparisons. You should be able to find both at a hospital pharmacy. They are not easy reading. That's why I prefer printed versions.

AHFSDI has annual updates. I got a freebie of one from a prior year. Once a pharmacy has the latest edition, they can give away the prior edition. Facts and Comparisons comes in a loose leaf binder. Sections are updated as warranted. The PDR, Physician's Desk Reference, is my last choice. It's just a compilation of the initial product information slips from the drug makers.

[neverdem]

A different anticoagulant is used for MIs. Integrilin is the standard anticoagulant for heart attacks per current best practice guidelines.

Thanks for the update. When did they stop using tPA when percutaneous coronary interventions with stents or coronary artery bypass grafting were not immediately available?