Down here in Texas, frostbite may not linger in the back of one’s mind much, if at all. However, when encountered with extreme weather and remote locations, frostbite can be serious and can result in amputation of precious fingers and toes.
A previous post (May 21 “Frostbite Management” ) details the basic evaluation and management of frostbite given relatively quick and easy access to secondary and tertiary care. This post will go deeper into the backcountry and higher up on the mountain to explore what options you have when you’re in the middle of nowhere with a frozen friend.
First, let’s quickly review the varying degrees of frostbite and basic management.
Severity of frostbite can be estimated by direct observation of the limb with grade 1 being the least severe (no cyanosis) and grade 4 most severe (cyanosis proximal to MP joint) requiring eventual amputation. Here are some general tips for dealing with frostbite:
- Minimize exposure, it is generally advisable to keep an extremity frozen if refreezing is likely. Obviously don’t intentionally maintain the limb at lower temperatures, but repetitive thaw-freeze cycles are injurious.
- If possible, get out of wet, cold clothes, and change into dry clothes
- If there is low risk of refreezing, immerse in warm water baths for 30-60 min or until skin is red/purple again and there is distal flushing
- Consider oral aspirin or ibuprofen for pain if available
- Do NOT rub the skin – can worsen direct tissue injury
But what if basic management isn’t enough?
What about situations where definitive evacuation is hours and maybe even days away? What options are there for field management? At this point, management depends on the severity of the injury, what resources are available, and the medical training of the provider.
Here is where we venture into new, proposed field treatment. Larger basecamps may have supplemental O2 or a hyperbaric chamber. If there is distal perfusion in the digit, O2 can help. The theory is that increased oxygenation (SpO2 >90%) at high altitudes can promote vasodilation and perfusion1,2. Key word: high altitude (i.e. >6000m). At lower altitudes, oxygen can actually induce vasoconstriction1. Another factor to consider is the effect of cold induced vasodilation in peripheral tissues (a protective mechanism). Acute hypoxia tends to diminish this effect whereas longer exposure to hypoxia (i.e. >1 week at high altitudes) may augment vasodilatory responses1,2. So in sum, oxygen can be helpful, can have minimal effect, or even have a counterproductive effect. Proceed with caution.
Trained medical professionals can consider the next three options depending on availability: distal sympathetic nerve block, IV rtPA infusion, or IV prostacyclin infusion.
It is known in hand surgery that distal nerve blocks cause vasodilation and increase skin temperature. This effect has yet to be studied in frostbitten tissue but benefits have been suggested. One case study by Pasquier et al. demonstrated a ropivacaine nerve block proximal to the wrist in 2 alpinists with grade 2 frostbite produced immediate pain relief and complete recovery4. Clearly there is still much to research for this method but if field options are limited, this is worth considering.
Depending on degree of medical expertise and resources available, it may be useful to consider rt-PA or iloprost in management. Iloprost is the less scary drug of the two as its side effects and complications are not as worrisome as rtPA. Iloprost or prostacylin analogs can be utilized if there are contraindications to rtPA, if the patient is out of the 24hr window for rtPA, or if the medical provider is not comfortable with using rtPA in the prehospital setting. Unlike rtPA, prostacyclin can be given up to 48 hours post thaw. The most common side effects to watch out for are postural hypotension and nausea/vomiting. All patients should be given 1 vial (total 25mL) of prostacyclin and administration rates can vary depending on tolerance (usually limited by nausea/vomiting)3 . Make sure that patients are supine when given prostacyclin analogs to prevent postural hypotension. Dilute 1 vial of 0.5mL iloprost in 24.5mL NS. Administer 25mL at 1mL/hr for 30 min, then 2mL/hr for 30 min, then 3mL/hr for 30 min then 4mL/h if patient weighs <75kg or 5mL/h if >75k1.
Finally, rtPA should be used only in severe cases of frostbite in which a) amputation is inevitable and b) there are no contraindications to tPA use. Spontaneous thawing has usually begun by the time diagnosis is made but thrombosis may have already occurred and can continue to pose a risk up to 16 hours post thaw3. While tPA is a drug generally reserved for administration in the hospital due to serious potential complications, it has been employed in prehospital care in countries other than the US. Consider this only if there is appropriate monitoring in the rare case of complications from rtPA administration.
There have been no randomized control trials of rtPA for frostbite, but there are a few case reports. The 2 patients presented by Cauchy et al. received rtPA for grade 4 frostbite in the hands, one within 24 hrs post-thaw who had a full recovery with no amputation and the other patient past 24 hrs with eventual amputation. Basic dose recommendations are 15mg IV bolus, then 0.75mg/kg over 30 minutes, then 0.35mg/kg over 60 minutes for patients <67kg. For heavier patients, use 15mg IV bolus, then 50mg over 30 min, then 35mg over 60min. Do not exceed 100mg1.
- Texans and Southerners: Stay warm and don’t forget about frostbite on your adventures. Frostbite can occur in temps as high as 10 degrees F given the right amount of wind-chill.
- Basic management: Minimize exposure, rewarm if there is low risk of refreezing, and use ibuprofen or aspirin
- Stuck somewhere? Consider oxygen/hyperbaric O2, distal sympathetic nerve block, prostacyclin infusion, or rtPA
- Administer rtPA only if amputation is inevitable and there are no contraindications, up to 24hrs post thaw
- Administer prostacyclin if rtPA not an option, up to 48 hrs post thaw
Until next time,
1. Emmanuel Cauchy, Christopher B. Davis, Mathieu Pasquier, Eric F. Meyer, Peter H. Hackett. A New Proposal for Management of Severe Frostbite in the Austere Environment. Wilderness & Environmental Medicine. Mar 2016, Vol. 27: 92-99
2. Keramidas ME, Kolegard R, Mekjavic IB, Eiken O. Acute effects of normobaric hypoxia on hand-temperature responses during and after local cold stress. High Alt Med Biol. 2014;15:183–191.
3. Ibrahim AE, Goverman J, Sarhane KA, Donofrio J, Walker TG, Fagan SP. The emerging role of tissue plas- minogen activator in the management of severe frostbite. J Burn Care Res. 2015;36:e62–e66.
4. Pasquier M, Ruffinen GZ, Brugger H, Paal P. Pre-hospital wrist block for digital frostbite injuries. High Alt Med Biol. 2012;13:65–66.