Tuesday, June 19, 2007

Advances in Northern Medicine

Frostbite is a common injury both in northern settings as well as in more unexpected places. Working in the arctic over the last 6 months I've seen quite a number of frostbite cases, but even when I was working in Vancouver I'd see the occasional frostbitten patient. That's right, Vancouver, Canada's tropics, has frostbite. In Vancouver frostbite is uncommon, but working on the Downtown Eastside I did see a couple of cases in homeless folks who had weathered a cold night outside with wet feet in poor footwear.

An article in this months Archives of Surgery, entitled Reduction of the Incidence of Amputation in Frostbite Injury With Thrombolytic Therapy, describes the use of intra-arterial tPA in patients with frostbite injury to a digit and demonstrated impaired perfusion. The article concludes by proclaiming that this is the first clinically significant advancement in the management of frostbite in more than 25 years. Indeed, as any northern doc can tell you, management of frostbite is limited.

A patient presents to the emergency department after passing out in a snow bank. Surprisingly his core temperature is adequate, but his hands appear white and frozen. At present the standard treatment for this patient involves:
  • pain control, usually with IV narcotics
  • rewarming of his hands by immersion in saline warmed to 42 degrees C
  • treatment of any hypothermia (with external, and often central rewarming)
  • debridement of any blisters containing clear or white fluid (these blisters represent more superficial injury, and contain PGF-2A and thromboxane, both of which can cause deeper injury through inflammation)
  • Hemmorhagic blisters are left intact as debridement can lead to increasing depth of injury, though aspiration can be considered.
  • Administration of an anti-inflamatory drug (Ibuprofen)
  • Tetanus booster if required
  • Telling the patient that they may not, under any circumstances, smoke (most people are able to not smoke when their fingers are at risk)
  • Surgical consultation (though early surgical intervention is avoided if possible, as even horrific looking injuries sometimes recover well)
The article suggests that the use of intra-arterial tPA may represent an advance in therapy that may save digits. This is exciting news to anyone who deals with frostbite, because at present effective interventions are limited, and poor outcomes can be disabling. There are limits to the study however, (small size, non-randomized, case control design, restriction to a single highly specialized institution) that prevent this from being a definitive and practice changing study. Certainly these results warrant a larger, multi-centre, randomized investigation. Given that many frostbite injuries occur in the periphery where timely access to intra-arterial thrombolysis is non-existent I do wonder if an arm of such a study examining systemic thrombolytic therapy might be warranted (though the risks of systemic therapy are also greater).


Midwife with a Knife said...

This is actually really neat. I grew up in Alaska, and had a few encounters with mild frostbite (nothing severe, just painful and enough to make my skin blister over a large part of my hands.) A friend of mine lost several toes to frostbite. It would be really neat to have a good way to treat the really severe injuries.

The Lone Coyote said...

Very interesting. I actually had a question on my boards prep the other day asking about treatment for a frostbite injury. I really had no idea since that is not part of our curriculum here, but did guess the right answer. Come to think of it, I am not sure why we never learned it because there are areas just a short drive away that have real winter-like weather.