Clinical Presentation of Frostbite
Frostbite presents with numbness, tingling, pain, and progressive skin color changes from pale to hardened and dark, with the extremities (fingers, toes, nose, and ears) being most susceptible to injury. 1
Pathophysiology and Mechanism
The fundamental mechanism of tissue damage involves formation of ice crystals within cells that destroy cell membrane integrity, causing both immediate cellular death and progressive inflammatory processes with tissue ischemia. 1 This dual injury pattern—direct freezing damage plus subsequent reperfusion injury—explains why clinical assessment can be challenging and why initial appearances may not reflect final tissue loss. 2
Primary Clinical Features
Sensory Changes
- A characteristic hallmark of acute frostbite is the complete inability to sense touch, including ongoing mechanical tissue damage. 1
- Patients with frostbitten hands or feet may be unaware of damage caused by continued movement or walking. 1
- Frozen tissue is numb during the freezing phase. 3
Skin and Tissue Appearance
- Skin color progresses from pale to hardened and dark as severity increases. 1
- The clinical presentation varies from superficial frostbite (affecting only outer skin layers) to severe cases involving deeper tissues and underlying structures. 1
- There may be wide discrepancy between skin damage and deeper structural injury, with initial clinical impression usually appearing worse than actual tissue damage. 2
Post-Rewarming Manifestations
- Rewarming causes hyperemia and is often painful, contrasting sharply with the numbness of frozen tissue. 3
- Blisters and edema develop after rewarming due to damaged capillary endothelium leaking fluid and protein. 3, 4
- Tissue swelling is a common inflammatory response attributable to increased fluid accumulation. 1
- Hard eschar may form with potentially healthy tissue deep to the eschar. 3
Anatomic Distribution
- The extremities are particularly susceptible: fingers, toes, nose, and ears are most commonly affected. 1
- This distribution reflects areas with limited blood flow and high surface area-to-volume ratios. 1
Severity Classification
Superficial Frostbite
- Affects only outer layers of skin without permanent tissue loss. 3
- May be sufficient to treat with simple rewarming measures. 5
Deep Frostbite
- Involves deeper tissues with varying degrees of permanent tissue loss. 3
- In extreme cases, can cause tissue necrosis leading to digit or limb loss. 1
- Often results in less tissue loss than initial appearances suggest. 3
Critical Assessment Challenges
- Estimating the size and severity of frostbitten tissue is challenging, especially in the first aid setting. 1
- It can be difficult to predict the amount of tissue loss at time of presentation and early in the subsequent course. 3
- The extent of damage to skin versus deeper structures may show wide discrepancy. 2
Associated Conditions
- Frostbite is a common finding in hypothermic individuals, requiring prioritization of core rewarming before extremity treatment. 1
- Rewarming extremities first in hypothermic patients can cause core temperature to decrease. 1