Page 129 - 2020 JSOM Winter

lower average and minimal skin blood flow. 48,49 These are all material to avoid trauma from mechanical damage. Clean, dry
factors that could increase susceptibility to frostbite. Other gauze or sterile cotton dressings can be placed between the
studies have found that risk of frostbite decreases as rank in- fingers and/or toes. Jewelry and other constrictive material
creases, 26,46 possibly related to greater exposure, duties, or ed- should be removed. The patient should be moved carefully
ucational level among lower ranking personnel. 26 from windy conditions by seeking shelter.
Other studies have identified additional risk factors for frost- Because repeated freezing and thawing can cause further dam-
bite. Environmental factors that increase the risk include age (Figure 1), the injured part should not be rewarmed unless
low temperature and high wind, 33,37,50,51 longer exposure to the patient can remain in a warm area. Rubbing the affected
cold, 26,44 and higher altitudes, especially >17,000 feet. Travel part should be avoided because it can cause further injury. If
32
in open vehicles increased risk, 31,36 likely because of exacer- the patient is capable, warm oral fluids can be provided to
bated wind speed. Military recruits lacking proper clothing maintain or improve hydration; if the patient is not capable of
31
had an increased risk of frostbite: lack of use of ear flaps in- orally consuming fluids, then normal intravenous saline (pref-
creased risk for frostbite of the ears, and lack of use of a scarf erably warmed to 37°C to 42°C [99°F–108°F]) can be pro-
increased risk for frostbite of the ears and face. Personal (i.e., vided, with consideration given to the fact that saline will cool
intrinsic) factors that increased risk of frostbite include birth- over time in colder environments. 16,21,57 Ibuprofen is generally
place in warmer regions, lower educational level, type O recommended because it reduces production of prostaglan-
26
26
blood (compared with A or B), excessive sweating, prior dins and thromboxanes that are associated with thrombosis
31
26
frostbite or frostnip injury, 37,52 and certain comorbidities (e.g., and ischemia (Figure 1). In the field, ibuprofen provided 12
58
cardiac insufficiency, angina pectoris, diabetes, depression). mg/kg twice daily is recommended up to a maximum of 2400
44
Cigarette smoking has been shown to increase risk in some mg/d total. 57
studies 26,38 but not all. 36,46 It has been hypothesized that acute
38
vasoconstriction observed with smoking, in concert with in- Rewarming can be accomplished slowly or rapidly, although the
53
creased fibrinogen concentration, increased platelet activity, latter is preferred, based on clinical experience. 23,57,59 In slow re-
and other factors, may exacerbate the thrombosis associ- warming, the patient is moved to a warm area and passively al-
54
ated with frostbite. Other risk factors include heavy physical lowed to rewarm. The affected body part can also be rewarmed
work, vibration exposure, use of topical ointments, 31,55,56 by another individual using their body heat (e.g., placing the pa-
44
38
and lack of proper equipment while mountineering. 39 tient’s hand in the axilla or groin of a buddy). Rapid rewarming
of the affected part in a water bath is much more effective and
is strongly recommended if available. The water bath should
Diagnosis
be heated to 37°C to 39°C (99°F–102°F) and a thermometer
As shown in Table 1, 78% of frostbite cases in the US mili- used to ensure accuracy of water temperature. In the absence of
tary have occurred in hands, fingers, feet, and toes, although a thermometer, a care provider can check the water by placing
15% occur in other specified locations (7% are recorded in a hand in it to assure it is tolerable. The water should be cir-
unspecified sites). In an initial clinical presentation, the pa- culated and the temperature checked frequently because it will
tient with frostbite presents with either frozen or thawed skin, cool once the affected limb is placed in it. The frozen part can
although in the field, the presentation is usually frozen skin. be considered adequately rewarmed when it assumes a red or
With skin in the frozen state, patients describe numbness and purple color and is soft and pliable to the touch. The length of
sensory loss in the affected area or areas and may complain time necessary for rewarming depends on the extent of the in-
of clumsiness and lack of control. The affected area is usually jury but is usually 15 to 60 minutes. Rewarming with excessive
cold, firm to the touch, and white, but could be mottled blue, heat (i.e., near campfires, stoves, or hot vehicle engines) should
yellow-white, and/or have a waxy appearance. As the tissue be avoided because of the possibility of thermal burns. Blisters
warms and thaws, it will appear red because of hyperemia, should not be débrided in the field. Once the affected part is
and the numbness will be replaced by a throbbing sensation removed from the water bath, edema should be expected. Loose
that can last for days or weeks. Edema and blistering (if pres- but bulky, dry sterile gauze should be placed around the affected
ent) occur during rewarming. Blisters that are clear, yellow, or part for protection and wound care. 23,57,59
pink and extend to the digits are favorable prognostic signs,
while small, dark, or hemorrhagic blisters generally indicate a Classification
less favorable prognosis. 17,21,23 Classification of frostbite is undertaken after rewarming be-
cause on initial presentation, most frozen skin appears sim-
ilar, regardless of the depth of tissue injury. 18,60 Examination
Treatment
should take into consideration skin color, skin temperature,
Field Care sensation, and pulse. As shown in Table 3, two classification
Recommendations for field management of frostbite are systems have been proposed to help determine the depth of the
based largely on clinical and practical experience. Because of injury and prognosis. The traditional system has four levels
the possibility of further injury and the loss of sensation in or degrees, whereas the more modern system has two levels.
affected parts, individuals with frostbite should not use the In the traditional system, first-degree frostbite involves only
frostbitten parts unless absolutely necessary. If only the toes superficial skin freezing that is essentially frostnip. There is no
are involved, it may be reasonable to walk for short distances; cyanosis, and on rewarming, the patient will report transient
however, it is not judicious to do so if the entire foot is in- tingling and burning. Erythema will be evident, and edema
volved. Nonetheless, there are anecdotal reports of individuals will occur after 2 to 3 hours. There may be some epidermal
who have walked for days on frozen feet. If locomotion is not skin loss. Second-degree frostbite involves freezing of both the
2
required or if frostbite involves only the hands, the affected epidermal and dermal skin layers. Cyanosis will be evident on
parts should be wrapped in clothing, blankets, or other cloth the frozen parts and, on rewarming, the patient will report

Frostbite | 127