I. Pathophysiology
A. Sensory nerve dysfunction occurs at 10°C.
B. Ice crystals form at -6°C to -15°C.
C. Most cellular injury occurs from intracellular dehydration when ice crystals form.
II. Evaluation
A. Superficial frostbite results in clear blisters.
B. Deep injuries secondary to frostbite may be anesthetic after thawing and form hemorrhagic blisters.
III. Management
A. Resuscitation is accomplished with warm intravenous fluids.
B. Rapid rewarming is accomplished using a water bath at 40° to 42°C for 30 minutes.
C. Blisters
1. Occur within 6 to 24 hours of rewarming
2. White blisters should be debrided.
3. Hemorrhagic blisters should be drained but left intact.
D. Topical antibiotics should be used to prevent superinfection.
IV. Late Effects
A. Young children—Late effects include premature physeal closure secondary to chondrocyte injury.
B. Older children—Once a child with prior frostbite injury reaches 10 years of age, short digits, excess skin, laxity of joints, and degenerative changes are observed.
C. Adults—Late effects include cold intolerance, hyperhidrosis, trophic changes, and Raynaud's phenomenon.
Top Testing Facts
1. Superficial frostbite results in clear blisters; deep injuries secondary to frostbite may be anesthetic after thawing and form hemorrhagic blisters.
2. Most cellular injury occurs from intracellular dehydration when ice crystals form.
3. Topical antibiotics should be used to prevent superinfection.
4. Late effects in young children include premature physeal closure; at 10 years of age children with prior frostbite injuries have short digits, excess skin, joint laxity, and degenerative changes.
5. Late effects in adults include cold intolerance, hyperhidrosis, trophic changes, and Raynaud's phenomenon.
Bibliography
Vogel JE, Dellon AL: Frostbite injuries of the hand. Clin Plast Surg 1989;16:565-576.