Evaluation

TRAUMA EVALUATION

All patients with identified cold injury should be considered trauma patients first to identify other life threatening injuries. If possible, attempt to establish the circumstances which led to prolonged environmental cold exposure. In addition, patients are likely hypothermic and should be warmed expediently before focusing on cold injuries of the extremities. In the field, cold extremities may be warmed as a consequence of treating a hypothermic patient. It is imperative to prevent refreezing of the impacted extremity as it results in more tissue damage.

COLD INJURIES

Cold injury is not a single diagnosis but rather a spectrum with all categories possibly present on a single extremity, the most distal portion usually being the most severely affected. Normothermia must be established prior to making the diagnosis of cold injury. Many people experience numbness of extremities with prolonged cold exposure with return to normal function without any permanent damage; this in isolation, will not result in cold injury. Cold injury has occurred when upon re-warming there is pain and swelling or gross signs of ischemia or skin injury. There are classically four degrees, with depth of injury distinguishing the different degrees:

First Degree: Superficial skin injury; pain on re-warming, numbness, hyperemia, occasional blue mottling, swelling and superficial desquamation (desquamation starts at about 5 days)

Second Degree: Partial thickness injury to skin; in addition to first degree findings, vesiculation of the skin surrounded by erythema and edema (appears around day 2)

Third Degree: Entire thickness of skin extending into subcutaneous tissue; bluish to black and non- deformable skin, hemorrhagic blisters, vesicles may not be present, eventual ulcerations can be expected; area will likely be surrounded by 1st or 2nd degree injury

Fourth Degree: Similar to third degree, but full thickness damage including bone. Area may be cold to touch and may feel stiff or woody.

Another way to classify is superficial (First and Second Degree) and full thickness (Third and Fourth Degree) similarly to burns. The ultimate grade will not be truly known until treatment has been attempted and a period of time has passed.

There are very mild cold injuries labeled as Chilblains and Frostnip that do exist, but for the sake of caution in the field, the recommendation is to treat all acute presentations as first degree (superficial) frostbite as there is no morbidity in correcting hypothermia and rapid rewarming of suspected areas. Chilblains is a chronic condition, like a dermatitis, and if continues after initial treatment cold avoidance and supportive care can be provided.

IMMERSION FOOT

Commonly known as trench foot, it is a syndrome related to prolonged exposure to moisture. Classically it has been associated with cold water, but can happen in all climates. The syndrome generally happens slower in warm water, taking approximately 48 hrs, than cold water (earliest estimate 12 hours).

The clinical presentation is water logging of the feet, most pronounced in the soles. With continuous exposure, the foot becomes hyperemic, mottled, painful and edematous, gradually progressing into blistering, hypoperfusion, ulceration and gangrene.8,9