Pathophysiology and assessment of burns

Abstract

Burn injury represents a complex clinical entity with significant associated morbidity and remains the second leading cause of trauma-related death. An understanding of the local and systemic pathophysiology of burns has led to significant improvements in mortality. Thermal insult results in coagulative necrosis of the skin and the depth or degree of injury is classified according to the skin layers involved. First-degree burns involve only epidermis and heal quickly with no scar. Second-degree burns are further classified into superficial partial thickness or deep partial thickness depending on the level of dermal involvement. Damage in a third-degree burn extends to subcutaneous fat. There is a substantial hypermetabolic response to severe burn, resulting in significant catabolism and untoward effects on the immune, gastrointestinal, and renal systems. Accurate assessment of the extent of burn injury is critical for prognosis and initiation of resuscitation. Burn size, measured in total body surface area, can be quickly estimated using the rule of nines or palmar method. A more detailed sizing system is recommended once the patient has been triaged. Appropriate diagnosis of burn depth will be important for later management. First-degree burns are erythematous and painful, like a sunburn; third-degree burns are leathery and insensate. Differentiating between second-degree burn types remains difficult. There are a number of formalized criteria during assessment that should prompt transfer to a burn centre.