Updated July 2026 · 9 min read

Frostbite & Cold Thermal Injury: The ICU Nurse's Deep Dive

Part of the ICU Emergencies Hub — browse every related guide in one place.

Frostbite is a burn made of ice. The tissue is injured twice — once by the freeze and again by the thaw — and much of what makes the outcome good or bad happens in the way you rewarm, what you do not do, and how long you wait before writing tissue off.

The two-hit injury: freeze, then thaw

Cold injures tissue in stages. During the freeze, ice crystals form in and around cells, drawing water out, concentrating solutes, and directly damaging cell membranes; vasoconstriction starves the part of blood. But a large share of the final tissue loss comes during and after rewarming: as the tissue thaws, injured endothelium triggers clotting and an inflammatory cascade in the small vessels, microthrombi form, and blood flow that briefly returns is choked off again. This reperfusion phase — progressive dermal ischemia — is where much of the salvageable tissue is lost, and it's why modern therapy targets the clotting and inflammation, not just the temperature.

Rapid rewarming: the technique that matters

The core intervention is rapid rewarming in a circulating warm-water bath at 37–39°C (about 98–102°F) until the part is thawed — typically pliable and red/purple — over roughly 15–30 minutes. Rapid is deliberately better than slow or dry rewarming for tissue survival.

Frostbite runs alongside hypothermia — treat the core first

Many frostbite patients are also systemically cold. Core rewarming and resuscitation of life-threatening hypothermia take priority over the frozen extremity — a warm, perfusing core is also what gives the limb its best chance. Restore central temperature and volume first, then attend to the local rewarming. The two problems travel together but the core comes first.

Grading, and why you don't declare early

Frostbite is often described in degrees that parallel burns, from superficial to deep:

Where thrombolytics fit in modern frostbite

Because so much of the damage is microvascular thrombosis during reperfusion, thrombolytic therapy (tPA) has become a limb-salvage option in selected severe cases. When deep frostbite is identified early (generally within a window of roughly 24 hours of thaw, with no perfusion on imaging and no contraindications to lysis), tPA — often with an anticoagulant, sometimes given intra-arterially at specialized centers — can dissolve the microthrombi, restore flow, and reduce the amount of tissue ultimately lost. Some centers also use the prostacyclin analog iloprost.

The nursing role, start to finish

Frostbite care sequences cleanly. Stabilize and rewarm the core first, confirm the environment can keep the part warm (no refreeze), then rapidly rewarm the extremity in 37–39°C water while giving generous analgesia. Avoid rubbing and dry heat. After the thaw, elevate, dress gently, leave clear blisters intact, and give tetanus prophylaxis. Flag severe deep frostbite early so the team can consider tPA within the treatment window — time is tissue. Then settle into the long game: protect the wound, watch for infection, support the patient through a weeks-long demarcation, and resist the urge (and the family's urge) to judge the final outcome from the first ugly appearance.

Why CRNA students should know it cold

On the CRNA path, frostbite reinforces two durable anesthesia lessons: reperfusion injury as a distinct, treatable phase (the same physiology behind tourniquet release and ischemic limbs), and the primacy of the core — you don't fix the periphery on a cold, under-resuscitated patient. The habit of treating the whole physiology before the visible injury is exactly what perioperative care demands.

Bottom line

Frostbite is a two-hit freeze-then-thaw injury. Rewarm the core first, then rapidly rewarm the part in 37–39°C water — but never thaw anything that might refreeze, never rub it, and never use dry heat. Medicate aggressively for rewarming pain, consider tPA early in severe deep frostbite to salvage tissue, and don't declare tissue dead until it demarcates over weeks.

This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols or a provider's orders. Always follow facility policy and verify every dose independently.