How are burn depths classified?

Updated: Jan 10, 2018
  • Author: Robert L Sheridan, MD; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Answer

Burn depths are routinely underestimated during the initial examination. [37] Devitalized tissue may appear viable for some time after injury, and often, some degree of progressive microvascular thrombosis is observed on the wound periphery. Consequently, the wound appearance changes over the days following injury. Serial examination of burn wounds can be very useful.

Burn depth is classified as first, second, third, or fourth degree, as follows: [37]

  • First-degree burns are usually red, dry, and painful. Burns initially termed first-degree are often actually superficial second-degree burns, with sloughing occurring the next day.

  • Second-degree burns are often red, wet, and very painful. Their depth, ability to heal, and propensity to form hypertrophic scars (see the image below) vary enormously.

    Initial evaluation and management of the burn pati Initial evaluation and management of the burn patient. Second-degree burns are often red, wet, and very painful. Their depth, ability to heal, and tendency to result in hypertrophic scar formation vary enormously.
  • Third-degree burns are generally leathery in consistency, dry, insensate, and waxy. These wounds will not heal, except by contraction and limited epithelial migration, with resulting hypertrophic and unstable cover. Burn blisters can overlie both second- and third-degree burns. The management of burn blisters remains controversial, yet intact blisters help greatly with pain control. Debride blisters if infection occurs. See the images below.

    Initial evaluation and management of the burn pati Initial evaluation and management of the burn patient. Third-degree burns are usually leathery in consistency, dry, and insensate. These wounds do not heal.
    Initial evaluation and management of the burn pati Initial evaluation and management of the burn patient. Management of burn blisters is controversial. Burn blisters occasionally obscure the presence of full-thickness wounds.
  • Fourth-degree burns involve underlying subcutaneous tissue, tendon, or bone. Usually, even an experienced examiner has difficulty accurately determining burn depth during early examination. As a general rule, burn depth is underestimated upon initial examination. [37]

Note circumferential, or near-circumferential, burn wounds because they may cause progressive extremity ischemia or interfere with ventilation as burn wound swelling increases. In such situations, timely escharotomy is essential. Perform extremity escharotomies as soon as peripheral perfusion is threatened. Do not wait until the extremity is overtly ischemic. Perform torso escharotomies as soon as ventilation appears compromised.


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