Page 130 - 2020 JSOM Winter

TABLE 3 Frostbite Classification Systems Based on Severity
Modern Classification Traditional Classification Signs and Symptoms
1st degree (superficial skin • Absence of initial lesion
freezing) • Erythema
• Edema (2–3 hours; may continue for 1 month)
• Minimal or absent initial lesions
• Blisters occasionally seen, but not often
• Occasional desquamation of skin (5–10 days later), but no deep
tissue loss
• Patient notes early transient tingling or burning, but generally intact
Superficial (freezing limited sensation
to skin) 2nd degree (full-thickness skin • Erythema
freezing [epidermis and dermis]) • Edema is likely, but disappears within a few days
• Initial lesion on distal phalanges
• Blisters with clear fluid (favorable prognosis) or hemorrhagic
(unfavorable)
• Hyperhidrosis (second or third week)
• Desquamation of skin
• Patient notes throbbing & aching pain lasting 3 to 10 days after
injury
3rd degree (full-thickness skin • Generalized edema
and subcutaneous tissue freezing) • Initial lesion on intermediary and proximal phalanges
• Purple or hemorrhagic blisters
• Some skin necrosis with hard, dry tissue (eschar)
• Sloughing of skin with ulcerations
• Patient notes no initial sensations, but later burning, aching,
throbbing or shooting pains
Deep (freezing involving skin
and tissues below the skin) 4th degree (full tissue freezing • Little edema
including muscle, tendon and • Initial lesion on carpal or tarsal
bone) • Hemorrhagic blisters (when blisters present)
• Initially area is cyanotic, mottled, or deep red; later area is dry
and black
• Extensive tissue necrosis & irreversible tissue damage
• Patient notes initial insensitivity in area and severe pain on
rewarming

throbbing and aching pain that can last 3 to 10 days postin- TABLE 4 Cauchy System for Classifying the Extent of Frostbite
jury. Erythema and blisters with clear or hemorrhagic fluid Amputation Risk of Hands and Feet. 61
will be evident. Hyperhidrosis occurs in the second or third Probability of Amputation
week. There will be loss of skin tissue. Third-degree frostbite Grade Extent of Involvement (%)
involves damage to the full thickness of the skin in addition to 1 Distal phalanx 0–1
subcutaneous tissues. The patient will report burning, aching, 2 Intermediary phalanx 23–39
throbbing, or shooting pains beginning about day 5 and last- 3 Proximal phalanx 60–83
ing 4 to 5 weeks. Blisters are smaller and can be hemorrhagic. 4 Metacarpal or metatarsal 98–100
There is a generalized edema that diminishes by day 5 or 6. 5 Carpal or tarsal 100
There is skin necrosis and sloughing of skin. In fourth-degree
frostbite, there is widespread destruction of tissue, including
the bone. The patient initially will report insensitivity in the uses the amount of anatomic involvement to indicate the prob-
affected area, but there is severe pain on rewarming. There is ability of amputation. The scale is based on clinical experience
little edema and, if blisters are present, they are hemorrhagic. with 494 affected fingers and toes in 70 severely frostbitten
Initially, the area is cyanotic, mottled, or deep red and later, patients. The scale does not predict where the amputation
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dry and black. There is extensive tissue necrosis and irrevers- should occur, which must be determined with imaging tech-
ible tissue damage. 17,21,23 Varying degrees of frostbite can exist niques described below. The much more involved Hennepin
in different parts of the body. score allows calculation of the extent of frostbite in the ex-
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tremities and can be used to indicate the effectiveness of treat-
The modern system better corresponds with the final prog- ment outcomes. It is to be used after triple-phase bone scans
nosis. 23,61 It simply classifies frostbite as either superficial and (described below), which indicate the level of tissue perfusion.
deep and is considered more appropriate for field classification To calculate an at-risk score, the system assigns 50 points to
after spontaneous or formal rewarming. Superficial frostbite each limb, then subdivides this value for various limb seg-
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is limited to the skin (no deeper tissues), has a good progno- ments. For example, 15 points are assigned to a hand (the ad-
sis for recovery, and encompasses the signs and symptoms of ditional 35 points are assigned to the rest of the arm), with a
traditional first- and second-degree frostbite. Deep frostbite single digit receiving 2 points. Of the two points, 0.5 point
involves the deeper tissues, is associated with tissue loss and is assigned to distal phalange involvement, 0.5 point to the
disability, and encompasses the signs and symptoms of tradi- middle phalange, and 1 point to the proximal phalange. If the
tional third- and fourth-degree frostbite. 17,23 phalanges of all five digits on a single hand are involved. the
patient is assigned a score of 10 points. Metacarpals and car-
Two additional systems have been developed to describe the pal involvement on a single hand are assigned an additional
extent of injury after rewarming. The Cauchy scale (Table 4) 5 points. The score describes the extent of tissue at risk, with

128 | JSOM Volume 20, Edition 4 / Winter 2020