tive medications, and external conditions such as high altitude exposure. Mechanical risk factors compose the final

category and are the most easily correctable. Common

examples include constrictive clothing and jewelry,

prolonged contact with heat conductive materials, and

immobility.

Of the 3 types of NFCI, frostnip is the least severe. It

typically affects the distal extremities after prolonged

exposure to cold but nonfreezing temperatures. Ice crystal

formation and profound vasoconstriction are common in

the superficial tissues, and patients frequently complain of

a dull throbbing pain during rewarming. Essentially a

precursor to frostbite, overt tissue destruction is lacking.

Chilblains (pernio) involve the formation of inflammatory skin lesions after repeated intermittent exposure to a

nonfreezing but cold and wet environment. Although

chilblains can affect any area of the body, the face, dorsal

surfaces of the hands and feet, and pretibial tissues are the

most commonly involved. Permanent tissue damage

secondary to vascular inflammation and tissue bed hypoxia

may develop. Women, children, and patients with

underlying vasculitides are most commonly affected.

263

CHAPTER 62

Immersion foot develops after the prolonged exposure

to persistently wet conditions, both warm and cold,

although the latter typically results in more severe tissue

injury. The long-term exposure to moisture induces tissue

edema and inflammation, whereas the prolonged cold

exposure leads to direct tissue injury. The consequently

encountered vasospasm, intravascular thrombosis, and

neuronal destruction can lead to full-thickness tissue loss.

Immersion foot is most commonly seen in the homeless

population.

Frostbite involves the freezing of tissues and can

result in significant tissue loss and long-term disability.

Ice crystal formation within the extracellular space can

induce intracellular dehydration, enzymatic dysfunc ­

tion, and cellular death. Microvascular occlusion sec ­

ondary to profound vasospasm and intraluminal

thrombosis further the severity of tissue loss. Circulating

tissue inflammatory markers frequently exacerbate the

intensity of tissue injury and complicate the reperfusion

of warmed tissue.

CLINICAL PRESENTATION

� History

Taking an adequate history should never delay the removal

of a patient from a cold environment. Inquire about

previous medical or psychiatric illnesses, drug and alcohol

use, and housing status. Any history of trauma should be

documented. Try to identify the overall duration of cold

exposure and elicit any previous history of frostbite or a

thawing and refreezing pattern of tissue injury. The review

of symptoms should attempt to discover the presence of

altered sensitivity, numbness, or burning pain.

Frostnip generally presents with numbness, pain,

pallor, and paresthesias of the ears, nose, fmgers, and toes.

Patients with chilblains typically present with complaints

of erythema, edema, and an intense pruritus or burning

sensation. Immersion foot is usually associated with

significant pain and swelling and occasionally numbness

and/or the inability to ambulate. Frostbitten patients

generally complain of the inability to feel the affected

areas.

� Physical Examination

Remove all clothing and thoroughly examine the entire

body, focusing primarily on the face, hands, lower legs and

feet, and buttocks and genitalia. Patients with frostnip may

present with paleness of the affected areas, but a normal

exam does not rule out injury. Chilblains frequently present

with erythema and edema and occasionally with vesicles,

bullae, and even ulcerations. The characteristic lesions are

purple or bluish in hue and appear 12-24 hours after exposure. Extremities affected by immersion foot will be swollen

and erythematous. Tissue sloughing is common, and there

may be an associated malodor. Frostbite typically presents

with mottled or violaceous tissue that may have a waxy

Figure 62-1. Deep frostbite of the toes.

.A. Figure 62-2. Superficial frostbite. Note the tissue

edema and clear bl isters.

appearance. Although frostbite can be classified similar to

burns into superficial and deep tissue injuries, this distinction

often cannot be made until the tissue is properly rewarmed.

Secondary blister formation is common, with the early formation of large clear blisters generally imparting a better

prognosis than the delayed development of smaller hemorrhagic bullae (Figures 62-1 and 62-2). Significant tissue

necrosis can complicate cases of deep tissue freezing despite

minimal initial physical exam findings.

DIAGNOSTIC STUDIES

Diagnostic studies of any kind are of limited utility in the

initial evaluation of patients with cold inducted tissue

injuries. That said, pursue radiographic and laboratory

studies as dictated for the evaluation of concurrent medical

COLD-INDUCED TISSUE INJURIES

illness or traumatic injury. Radionuclide bone scanning

and magnetic resonance imaging may a prognostic role in

long-term management.

MEDICAL DECISION MAKING

Include cold-induced tissue injuries in the differential diagnosis of all patients exposed to freezing or near freezing

temperatures, but evaluate and treat for any life-threatening

conditions before dealing with these injuries. Check the c ore

body temperature of all cold exposed patients to rule out

hypothermia. Investigate for and address any concurrent

trauma or dehydration. Attempt to delineate between freezing and nonfreezing injuries, as the treatments will differ. If

unclear between the two, always err on the side of frostbite

and treat accordingly. Consider compartment syndrome in

frostbitten regions if the swelling does not resolve and pulses

do not return after adequate rewarming.

Keep in mind that other injuries or illnesses can both

mimic and contribute to cold-induced tissue injury.

For example, the erythema of rewarmed frostnip and

immersion foot can resemble cellulitis or deeper tissue

infections. Peripheral vascular disease and vasculitides not

only appear similar to both frostbite and chilblains but also

increase their likelihood secondary to impaired microvascular circulation. Finally, the color changes and blisters of

frostbite can be confused with both stasis dermatitis and

autoimmune bullous forming conditions (Figure 62-3 ).

Add ress hypothermia,

dehydration and life

threats

Ambient rewarming

Figure 62-3. Cold-ind uced tissue injuries

diag nostic algorithm.

TREATMENT

All clothing should be removed and replaced with warm

blankets. Wet clothing is especially problematic as it will

continue to cool the patient during treatment. Dehydration

is a common complicating condition and requires

aggressive volume resuscitation with intravenous (IV)

crystalloids to lessen blood hyperviscosity. All body parts

that have suffered cold-induced tissue injury will need

some type of rewarming, with the pattern of injury

sustained determining the appropriate modality.

Frostnip usually resolves spontaneously with dry

rewarming measures at room temperatures and requires

no further intervention. Rewarm chilblains affected skin at

room temperature and then wash, dry, and dress in a soft

sterile bandage. Initiate pain control as needed and elevate

the affected extremity to prevent excessive edema

formation, as this will predispose to subsequent infection.

Patients with recurrent episodes may benefit from

treatment with oral nifedipine (30-60 mg/day), and topical

and systemic corticosteroids have both shown promise in

certain patient cohorts.

Immersion foot requires slightly more detailed care.

Rewarm affected tissues at room temperature and allow

them to air dry. Restrict patients to bed rest and elevate the

affected extremities during the rewarming period. Certain

patients may achieve adequate pain relief with oral

nonsteroidal anti-inflammatory drugs, whereas others may

require parental opioid analgesia. The early use of t ricyclic

antidepressants may help limit the future development of

chronic neuropathic pain. Extreme cases of immersion

foot may be indistinguishable from frostbite and should be

treated as the latter until proven otherwise. Finally, all

patients with NFCI require clear instructions to limit their

potential for recurrent exposure and injury.

Frostbite requires more aggressive treatment to limit

progressive tissue damage. Rewarm all affected areas in a

warm water recirculating bath ( 40-42°C) with a mild antibacterial agent mixed in (eg, povidone-iodine or chlorhexidine).