Cold-Related Injuries

Shiver Me Timbers - Hypothermia Unveiled

• Definition: Core body temperature (CBT) <35°C (95°F).
• Pathophysiology: Heat loss > heat production. Progressive multi-system dysfunction: CNS depression, ↓cardiac output, ↓metabolic rate, coagulopathy.
• Key Risk Factors: Extremes of age, alcohol, sedatives, hypothyroidism, hypoglycemia, trauma, prolonged cold exposure/immersion.
• Severity Stages (CBT):
  • Mild (HT I): 32-35°C. Shivering, confusion, slurred speech, ataxia, tachycardia.
  • Moderate (HT II): 28-32°C. Shivering stops, ↓LOC (stupor), bradycardia, hypotension, Osborn J wave, arrhythmias (e.g., AF).
  • Severe (HT III): <28°C. Coma, VF/asystole, areflexia, fixed pupils, pulmonary edema, oliguria.

⭐ Osborn J wave: Slow positive deflection at ECG's J point (QRS-ST junction). Characteristic of hypothermia, especially with CBT <32°C.

Code Blue Cold - Hypothermia's Grip

• Core body temperature < 35°C (95°F).
• Stages & Features:
  • Mild (32-35°C): Shivering, confusion. EKG: Osborn J wave may start.
  • Moderate (28-32°C): Shivering stops, ↓LOC, bradycardia, hypotension. EKG: Prominent Osborn J wave, Atrial Fibrillation (AF).
  • Severe (<28°C): Coma, areflexia, Ventricular Fibrillation (V-fib)/asystole.
• EKG: Osborn J wave (J-point elevation), bradycardia, prolonged intervals (PR, QRS, QT), arrhythmias.
• Management:
  • ABCDEs, remove wet clothes, gentle handling (prevents arrhythmias).
  • Core temp monitoring (esophageal, rectal, bladder).
  • Rewarming strategies:
    • Mild: Passive external rewarming (warm environment, blankets).
    • Moderate: Active external rewarming (forced air, warm packs) + warmed IV fluids (40-42°C). Rewarm at 1-2°C/hr.
    • Severe: Active core rewarming (warmed IV fluids, warm humidified O2, body cavity lavage, ECMO/CPB).

⭐ "No one is dead until they are warm and dead": Continue CPR until core temperature >32-35°C if in hypothermic cardiac arrest.

• Flowchart: Hypothermia Management

Nip in the Air - Frostbite's Facts

• Localized tissue freezing from cold. Pathophysiology: ice crystals, cell damage, microvascular thrombosis, inflammation.
• Classification (Degrees):
  • 1st: Superficial, erythema, edema, no blisters.
  • 2nd: Large clear blisters, erythema, edema.
  • 3rd: Small hemorrhagic blisters, blue-gray skin, deeper.
  • 4th: Full-thickness, mummification, autoamputation.
• Clinical: Initial pallor/numbness, then throbbing pain on rewarming. Blisters 24-48 hrs post-rewarming.
• Management:
  • Rapid rewarming: water at 37-39°C for 15-30 min.
  • Analgesia (NSAIDs). Tetanus prophylaxis.
  • Topical aloe vera.
  • Avoid friction. No rewarming if refreezing risk.
  • Delayed debridement (3-6 weeks).
  • Severe cases: IV Iloprost/tPA (within 24 hrs).
• Complications: Chronic pain, cold sensitivity, hyperhidrosis.

⭐ Exam Favourite: Amputation or debridement in frostbite is delayed for 1-3 months for tissue demarcation, unless wet gangrene/infection occurs.

Chills & Spills - Beyond the Freeze

• Trench Foot (Immersion Foot): Non-freezing injury from prolonged exposure to damp, cold conditions (0-15°C).
  • Pathophysiology: Vasoconstriction, ischemia, direct nerve/tissue damage.
• Chilblains (Pernio): Painful, itchy inflammatory skin lesions (papules, plaques) on extremities after exposure to cold, damp conditions (above freezing).

⭐ Recurrent chilblains warrant investigation for underlying systemic disease.

• Prevention: Keep warm & dry, appropriate layered clothing, avoid prolonged immobility, maintain hydration & nutrition. 侵

High‑Yield Points - ⚡ Biggest Takeaways

• Frostnip: superficial, reversible cold injury; gentle rewarming.
• Chilblains (Pernio): painful, itchy inflammatory lesions from chronic, damp cold.
• Trench Foot: non-freezing, wet cold exposure; causes neurovascular damage.
• Frostbite: tissue freezing, ice crystals. Classified 1st-4th degree by depth.
• Superficial frostbite: clear/milky blisters (2nd deg). Deep frostbite: hemorrhagic blisters, mummification.
• Frostbite rewarming: rapid, in 37-39°C water. Avoid rubbing and refreezing.
• Hypothermia (<35°C): J waves (Osborn waves) on ECG; severe cases need active core rewarming.