0071643192.pdf

ENVIRONMENTAL EMERGENCIES

SYMPTOMS/EXAM

■ Transient numbness and tingling, resolves with rewarming

■ Affected skin appears firm, cold, and white.

■ Superficial blistering and peeling may occur.

TREATMENT

■ Rewarm.

■ Prevent further cold exposure.

Frostbite

The most common freezing injury of tissue that occurs when tissue temperatures

drop below 0°C (32°F). Ice crystal formation damages cellular architecture lead-

ing to microvascular thrombosis, ischemia, and eventual tissue necrosis.

Only after rewarming of tissue can depth of injury can be assessed.

Traditional classificationof frostbite:

■ First-degree:Central white plaque with surrounding hyperemia

■ Second-degree:Clear blisters

■ Third-degree:Hemorrhagic blisters →eschar and tissue loss

■ Fourth-degree: Focal necrosis →tissue loss

However, the above classification has no impact on treatment, so a simpler

classification is often used.

■ Superficial frostbite: No evidence for tissue loss

■ Deep frostbite: Evidence for tissue loss

PATHOPHYSIOLOGY

■ Tissue freezing → release of arachidonic acid breakdown products

(prostaglandins and thromboxane) →thrombosis and ischemia.

SYMPTOMS/EXAM

■ Before rewarming:

■ Affected area appears mottled, pale, firm, and waxy.

■ Extremity may feel numb or “wooden.”

■ After rewarming: Blisters and focal necrosis develop.

■ Dead tissue demarcates in 22–45 days.

TREATMENT

■ Treat any associated hypothermia first.

■ Rapid rewarming:

■ Immerse in 40–42°Ccirculating water until tissue feels pliable.

■ Opioid analgesia is often needed.

■ Avoid:

■ Friction or rubbing of skin

■ Dry heat

■ Refreezing (disastrous!)

■ IV hydration

■ Tetanus prophylaxis

■ Blisters

■ Debride ONLY if broken

■ Otherwise,aspirate or leave intact

Rewarm by immersion in

40 °–42°C circulating water.