Thermal Injuries

Burn Basics - Sparking Knowledge

• Definition: Tissue injury: thermal, chemical, electrical, radiation.
• Types:
  • Thermal: Scalds, flame, contact.
  • Chemical: Acids (coagulation necrosis); Alkalis (liquefaction necrosis - severe).
  • Electrical: Entry/exit wounds; cardiac risk.
• Burn Depth (Degrees):
  • 1st (Superficial): Epidermis. Red, painful.
  • 2nd (Partial Thickness): Dermis.
    • Superficial: Blisters, very painful.
    • Deep: Mottled, ↓ pain, scars.
  • 3rd (Full Thickness): All layers. Leathery, insensate. Grafting.
  • 4th: To muscle/bone.
• Severity (TBSA %):
  • Rule of Nines (Adults): Head/Neck 9%, Arm 9% (each), Leg 18% (each), Ant. Trunk 18%, Post. Trunk 18%, Perineum 1%.
  • Lund-Browder Chart: For children.
  • Palm Method: Patient's palm ≈ 1% TBSA.

⭐ Inhalation injury (facial burns, sooty sputum) ↑ mortality in burns.

Body's Inferno - Systemic Sizzle

• Burn Shock:
  • Patho: ↑ Capillary permeability → hypovolemia (fluid loss).
  • Maximal edema: 24-48 hrs.
  • Phases: "Ebb" (↓metabolism, 0-48h), "Flow" (↑hypermetabolism).
• SIRS & MODS:
  • Cytokines (TNF-α, IL-1, IL-6) → systemic inflammation, MODS.
• Metabolic Derangements:
  • Hypermetabolism: ↑ Catecholamines, cortisol. RME ↑ up to 100%.
  • ↑ Protein catabolism, hyperglycemia, insulin resistance.
• Inhalation Injury: Major mortality cause.
  • Upper airway: Thermal edema.
  • Lower airway/Parenchymal: Chemical pneumonitis (smoke) → ARDS.
  • Systemic: CO poisoning (carboxyhemoglobin >10-15% symptomatic, >20% toxic), Cyanide.
  • Signs: Facial burns, singed nasal hairs, soot, hoarseness.
• Complications:
  • Immunosuppression → Sepsis (Pseudomonas aeruginosa).
  • Renal: ATN (hypoperfusion/myoglobinuria).

  ⭐ Curling's ulcer: Stress ulcer (stomach/duodenum) post-severe burns.

  • Hematologic: Anemia, coagulopathy.

Postmortem Puzzles - After the Ashes

• Antemortem (AM) vs. Postmortem (PM) Burns:
  • Vital Reactions: Redness, blisters (albumin-rich), pus, inflammatory line in AM. Absent in PM.
  • Soot in Airway: In trachea/bronchi indicates AM burning.
  • COHb Levels: ↑ (>10%) suggests AM smoke inhalation.

    ⭐ Cherry-red discoloration of tissues/blood indicates CO poisoning (COHb >20-30%), a vital sign in fire victims.

• Pugilistic Attitude:
  • Boxer's stance from heat-induced muscle coagulation.
  • Occurs in both AM & PM burns; not a sign of struggle.
• Heat Ruptures:
  • Irregular skin splits, everted edges, no hemorrhage.
  • Differentiate from AM wounds.
• Heat Hematoma: Epidural, brick-red, honeycomb appearance; heat-induced, not trauma.
• Crow's Feet Sign: Spared wrinkles at eye corners; eyes closed during AM burn.

Special Cases - Shocking & Scalding

• Scalds (Hot Liquids/Steam)
  • Patterns: glove & stocking, tide marks, zebra stripes (clothing folds), splash/drip.
  • Immersion: sharp demarcation.
• Electrical Injuries
  • Joule burn: internal heating ($H = I^2Rt$).
  • AC: more dangerous; tetany ("no-let-go"); Ventricular Fibrillation (VF) at ~25-100 mA.
  • DC: single convulsion; asystole at >300 mA.
  • Entry: small, pale, depressed, charred center.
  • Exit: larger, everted, "exploded".
• Lightning Injuries
  • Lichtenberg figures (ferning): pathognomonic, transient.
  • TM rupture, cataracts, keraunoparalysis.

  ⭐ Lichtenberg figures are pathognomonic for lightning strikes, not true burns, and fade within 24 hours.

High‑Yield Points - ⚡ Biggest Takeaways

• Rule of Nines estimates adult TBSA; Lund-Browder chart for children.
• Soot in airways and elevated carboxyhemoglobin (>10%) are vital signs of antemortem burns.
• Pugilistic attitude is a postmortem heat artifact, not a sign of struggle.
• Heat hematoma (epidural) is a postmortem artifact, distinct from traumatic hemorrhage.
• Cherry-red discoloration suggests CO poisoning; >50-60% COHb is often fatal.
• Scalds show clear demarcation and run-off patterns; flame burns cause singeing of hairs and skin.