12.2 Thermal/Chemical Burns, Parkland Formula & Wound Management

Evaluation and Management of Burns

Burn injuries require immediate, specialized care to mitigate systemic shock, prevent infection, and optimize functional outcomes. Management is categorized into immediate resuscitation (primary survey), burn assessment (calculating extent and depth), and definitive wound care. In Saudi Arabia, where industrial accidents and domestic fires occur, familiarity with burn protocols is essential for the SMLE.

Initial Assessment and Airway Management

The initial approach to a burn patient follows the standard ATLS primary survey. However, the airway requires particular vigilance. Inhalation injury is a major cause of mortality and can rapidly lead to airway edema and obstruction.

Signs of Inhalation Injury:

• Facial burns or singed facial/nasal hair
• Carbonaceous (sooty) sputum
• Hoarseness, stridor, or wheezing
• History of a fire in an enclosed space

If inhalation injury is suspected, early prophylactic endotracheal intubation is indicated before progressive edema makes the airway impossible to secure. Additionally, all victims of fires in enclosed spaces should be evaluated for carbon monoxide (CO) poisoning. The diagnosis is confirmed by an elevated carboxyhemoglobin level. The treatment for CO poisoning is 100% oxygen via a non-rebreather mask, which significantly decreases the half-life of CO.

Estimating Burn Size: The Rule of Nines

Accurate estimation of the Total Body Surface Area (TBSA) involved is critical for calculating fluid resuscitation requirements. Only partial-thickness (second-degree) and full-thickness (third-degree) burns are included in the TBSA calculation; superficial (first-degree) burns like mild sunburns are excluded.

The Rule of Nines is the most widely used method for adults:

• Head and Neck: 9%
• Anterior Torso: 18%
• Posterior Torso: 18%
• Each Upper Extremity: 9% (anterior 4.5%, posterior 4.5%)
• Each Lower Extremity: 18% (anterior 9%, posterior 9%)
• Genitalia/Perineum: 1%

Note for Pediatrics: The proportions differ in children, who have relatively larger heads (up to 18%) and smaller legs.

Fluid Resuscitation: The Parkland Formula

Severe burns lead to massive fluid shifts, capillary leak, and distributive/hypovolemic shock. Intravenous fluid resuscitation is indicated for any adult with >15-20% TBSA burns. Lactated Ringer's (LR) is the preferred crystalloid because its composition closely matches extracellular fluid, and it helps buffer the metabolic acidosis common in burn shock.

The classic Parkland Formula calculates the total fluid requirement for the first 24 hours post-injury:

Total Fluid (mL) = 4 mL x Weight (kg) x % TBSA burn

Administration Schedule:

• Give half (50%) of the total calculated volume over the first 8 hours (calculated from the time of the burn, not the time of hospital arrival).
• Give the remaining half (50%) over the subsequent 16 hours.

Modern ATLS Update: Recent guidelines recommend starting resuscitation at 2 mL/kg/%TBSA for adults with thermal burns to avoid over-resuscitation (fluid creep), while maintaining 4 mL/kg/%TBSA for electrical burns and pediatric patients. Always follow the specific parameters given in a question stem.

Worked Example

A 70 kg man sustains 30% TBSA thermal burns at 13:00. He arrives at the ED at 14:00. Using the 4 mL formula:

• Total 24-hour fluid = 4 mL x 70 kg x 30 = 8,400 mL.
• First 8 hours requires 4,200 mL. Since 1 hour has already passed since the injury, this 4,200 mL must be given over the next 7 hours (rate = 600 mL/hr).
• Next 16 hours requires 4,200 mL (rate = 262.5 mL/hr).

The most reliable indicator of adequate fluid resuscitation is urine output, aiming for 0.5 mL/kg/hr in adults (or 1.0 mL/kg/hr in pediatric patients).

Burn Depth and Wound Management

Understanding burn depth dictates the local wound management strategy.

Escharotomy

Full-thickness burns produce an inelastic, leathery eschar. When these burns are circumferential around an extremity, the underlying tissue edema can cause a tourniquet effect, leading to compartment syndrome and limb ischemia. Circumferential burns of the chest wall can restrict ventilation. The treatment is an escharotomy—surgical incisions through the eschar to release the pressure.

Chemical and Electrical Burns

Chemical Burns: The cornerstone of management for chemical burns (both acidic and alkali) is immediate and copious irrigation with tap water or saline for at least 30 minutes. Do not waste time searching for a neutralizing agent, as the neutralization reaction is exothermic and can cause superimposed thermal injury. Alkali burns (e.g., lye, cement) tend to be deeper and more severe than acid burns because they cause liquefactive necrosis, which penetrates tissues deeply, whereas acids cause coagulative necrosis, which forms a protective eschar.

Electrical Burns: Electrical burns can cause massive deep muscle destruction (rhabdomyolysis) despite minimal visible skin injury. This can lead to myoglobinuria and acute kidney injury. Management requires aggressive fluid resuscitation (using the 4 mL/kg/%TBSA formula) and aiming for a higher urine output (1.0 to 1.5 mL/kg/hr) to flush the myoglobin through the kidneys. Patients must also be monitored for cardiac arrhythmias.