Burn Assessment Fundamentals
Burns are tissue injuries caused by thermal, chemical, electrical, or radiation energy. Burn severity depends on three factors: depth (how deep the burn penetrates), extent (how much body surface area is affected), and location (burns to the face, hands, feet, genitalia, and joints are more serious regardless of depth). Accurate assessment of these factors guides treatment decisions and determines whether the patient requires transfer to a specialized burn center.
Burns cause both local tissue destruction and systemic effects. Locally, burns destroy skin integrity, leading to fluid loss, infection risk, and pain. Systemically, large burns trigger an inflammatory response that can cause massive fluid shifts, airway edema, hypovolemic shock, and metabolic derangements. Burns involving more than 20% of total body surface area (TBSA) in adults require aggressive IV fluid resuscitation to prevent burn shock.
Burn Depth Classification
- Superficial (first degree): Involves only the epidermis. The skin is red, dry, and painful. Sunburn is the classic example. These burns heal within 5 to 7 days without scarring and do not count toward TBSA calculations for fluid resuscitation.
- Partial thickness (second degree): Involves the epidermis and varying depths of the dermis. Superficial partial thickness burns are red, moist, blistered, and very painful. Deep partial thickness burns may appear pale or mottled, with decreased sensation. Partial thickness burns heal within 2 to 4 weeks, though deep partial thickness burns may require skin grafting.
- Full thickness (third degree): Involves the entire dermis and may extend into subcutaneous tissue. The burn appears white, brown, or black, with a leathery texture. These burns are painless at the center (because nerve endings are destroyed) but painful at the edges where partial thickness burns transition. Full thickness burns require skin grafting.
- Fourth degree: Extends through the skin into muscle, tendon, or bone. These are devastating injuries associated with prolonged contact with heat sources, high-voltage electrical burns, or chemical burns.
Body Surface Area Estimation
The Rule of Nines divides the adult body into regions, each representing 9% (or a multiple of 9%) of total body surface area: head and neck (9%), each upper extremity (9%), anterior trunk (18%), posterior trunk (18%), each lower extremity (18%), and perineum (1%). For children, the head is proportionally larger (18%) and the legs are smaller (14% each). For small or irregular burns, the patient's palm (including fingers) represents approximately 1% of their TBSA.
Prehospital Burn Management
Stop the burning process first: remove the patient from the heat source, remove smoldering clothing (but do not pull off clothing that is stuck to the skin), and brush off dry chemicals before flushing with water. Cool the burn with room temperature water for small burns (less than 10% TBSA). Do not use ice, which causes vasoconstriction and worsens tissue damage. For large burns, do not apply water extensively, as this can cause hypothermia; cover with clean, dry sheets instead. Remove jewelry and constricting items before swelling develops. Manage pain aggressively: burns are intensely painful. Establish IV access in unburned skin if possible. Begin fluid resuscitation for burns greater than 20% TBSA (the Parkland formula calculates 4 mL times body weight in kg times %TBSA, with half given in the first 8 hours). Transport to a burn center for significant burns per ABA referral criteria.