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Third-Degree Burns: Temperature Thresholds, Causes, and Emergency Management

Temperature and Time Relationship

Third-degree (full-thickness) burns destroy epidermis, dermis, and often subcutaneous tissue. The temperature-time relationship follows a logarithmic curve:

TemperatureTime for Full-Thickness Burn
140°F (60°C)5 seconds
149°F (65°C)2 seconds
156°F (69°C)1 second
162°F (72°C)0.5 seconds
Boiling Water (212°F/100°C)Instantaneous
Flame/Fire (>1100°F/600°C)Instantaneous

Key Variables: Skin thickness (thinner in elderly/children), moisture (wet skin burns faster), pressure, duration, and tissue perfusion.

Common Causes

  • Scalds: Hot liquids (water, oil, beverages) – #1 cause in children/elderly.
  • Flame: House fires, clothing ignition, accelerants – #1 cause in adults.
  • Contact: Hot surfaces (stoves, irons, heaters, machinery).
  • Electrical: High voltage (>1000V) – deep tissue destruction along current path; "iceberg effect" (skin entry/exit small, deep damage extensive).
  • Chemical: Strong acids/alkalis (lye, cement, hydrocarbons) – liquefactive/coagulative necrosis continues until neutralized.
  • Radiation: Nuclear, industrial; delayed presentation.

Clinical Identification

  • Appearance: White, brown, black, charred, leathery, waxy; no capillary refill.
  • Sensation: Anesthetic (nerve endings destroyed) – distinguishes from deep partial-thickness (painful).
  • Blanching: Absent.
  • Eschar: Thick, inelastic necrotic tissue forms.

Emergency Management

  1. Stop Burning Process: Remove from source; cool with cool (not ice) water 10-20 min (thermal only).
  2. ABCs: Airway (inhalation injury?), Breathing, Circulation.
  3. Remove Constrictive Items: Jewelry, clothing (not adherent fabric).
  4. Cover: Clean, dry, non-adherent dressing; avoid ointments/creams pre-hospital.
  5. Fluid Resuscitation: Parkland formula (4 mL × kg × %TBSA lactated Ringer's, half in first 8 hrs) for >20% TBSA adults, >10% children.
  6. Tetanus Prophylaxis: Update if >5 years.
  7. Referral Criteria (ABA): >10% TBSA, face/hands/feet/genitals/perineum/major joints, electrical/chemical, inhalation, comorbidities, extremes of age.

Definitive Treatment

  • Early tangential excision (within 72 hrs) + autografting.
  • Temporizing: allograft, xenograft, synthetic dermal substitutes (Integra®).
  • Multidisciplinary: surgery, critical care, nutrition, rehab, psychology.

Third-degree burns never heal spontaneously; require surgical intervention. Survival improved dramatically with early excision, aggressive resuscitation, and specialized burn center care.

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