Prehospital Academy Lesson 31.2
Burn Treatment for the EMT Provider
Burn injuries represent a multi-systemic metabolic crisis that extends far beyond the localized destruction of the integumentary system. For the EMT, managing a major burn requires a deep understanding of fluid dynamics, inhalation toxicology, and the histological progression of thermal wounds. This lecture companion explores the cellular zones of injury, the "toxic twins" of combustion, and the specialized assessment frameworks used to predict mortality and guide resuscitation.
Histological Progression: Jackson's Zones of Coagulation
The severity of a thermal insult is best understood through Jackson's Zones, which describe the three-dimensional architecture of a burn wound:
Zone of Coagulation: The central point of maximum heat absorption. Myocardial and cellular proteins are denatured, leading to irreversible necrosis and microvascular occlusion.
Zone of Stasis: Surrounds the necrotic core. This tissue is characterized by reduced perfusion and precarious viability. Without aggressive Fluid Resuscitation and the prevention of further heat transfer, this zone will convert to permanent necrosis.
Zone of Hyperemia: The outermost ring, where vasodilation occurs due to the inflammatory response. This tissue is typically viable and will recover within 7-10 days.
The Dynamics of Burn Shock and Fluid Resuscitation
Major burns induce Burn Shock, a unique combination of hypovolemic and distributive shock. This is driven by systemic "capillary leak syndrome," where inflammatory mediators (histamine, serotonin, prostaglandins) cause massive fluid shifts from the intravascular space to the interstitial space.
The Parkland (Baxter) Formula
While definitive fluid therapy occurs in the hospital, the EMT must understand the volume requirements: 4 mL x Weight (kg) x %TBSA. Half of this volume is administered in the first 8 hours post-injury. Failure to initiate early hydration leads to renal failure due to Acute Tubular Necrosis (ATN), exacerbated by the release of myoglobin from damaged muscle (Rhabdomyolysis).
Assessment of Total Burn Surface Area (%TBSA)
While the Rule of Nines provides a rapid field estimate, the Lund-Browder Chart is the gold standard for pediatric patients, as it accounts for the disproportionate surface area of a child�s head compared to their limbs.
Inhalation Injury and the "Toxic Twins"
Inhalation injury is the primary predictor of mortality in fire-related trauma. The Baux Score (Age + %TBSA + 17 [if inhalation injury present]) is often used to estimate the probability of mortality.
Carbon Monoxide (CO): CO has a 200-250x higher affinity for hemoglobin than oxygen. It shifts the oxyhemoglobin dissociation curve to the left, preventing the release of what little oxygen is available to the tissues.
Hydrogen Cyanide (HCN): Often released from burning synthetic materials, HCN inhibits Cytochrome C Oxidase in the mitochondria, halting aerobic metabolism even in the presence of adequate oxygen (histotoxic hypoxia).
Upper Airway Edema: Thermal injury to the supraglottic airway causes rapid, life-threatening swelling. The presence of Stridor or Hoarseness indicates an imminent total airway occlusion.
Specialized Burn Considerations
Electrical Trauma: The Iceberg Effect
Electrical current follows the path of least resistance (nerves and blood vessels), causing deep tissue destruction that is not visible on the surface. The most critical complication is Delayed Ventricular Fibrillation and rhabdomyolysis leading to dark, "tea-colored" urine (Myoglobinuria).
Circumferential Burns and Escharotomy
Full-thickness burns create a non-compliant, leathery layer called Eschar. If the burn is circumferential to a limb or the chest, the edema underneath creates a "tourniquet effect," leading to Compartment Syndrome. An Escharotomy�a surgical incision through the eschar�is required to restore distal perfusion or allow for chest wall expansion.
Critical Thinking Questions
Explain the physiological mechanism of "Capillary Leak Syndrome" in burn shock. Why does this lead to both hypovolemia and edema?
Using the "Toxic Twins" (CO and HCN) as a framework, describe why a pulse oximeter reading of 98% is a dangerously unreliable metric in a smoke inhalation victim.
Why is the Lund-Browder Chart considered superior to the Rule of Nines when assessing a 2-year-old child with significant burns to the head and chest?
Describe the renal consequences of an electrical burn. How does the release of myoglobin from damaged muscle fibers lead to Acute Tubular Necrosis?
Contrast the management of a dry chemical burn with a hydrofluoric acid burn. Why is the latter considered a systemic medical emergency beyond the skin injury?