Thermal Burns and Inhalational Injuries

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What characteristics describe the various degrees of burns?

The historical classification of burns was first established almost 200 years ago and was based on the depth of the burn and is still utilized today. First-degree burns are superficial. Second-degree burns are partial-thickness. Third-degree burns are full-thickness. Although less frequently utilized, higher-grade burn descriptions also exist. Fourth-degree burns extend into the underlying soft tissue. Fifth-degree burns extend beyond muscle and to the level of bone, and sixth-degree burns actually involve the bone.

• Superficial burn is now the preferred terminology instead of first-degree burns. There is no involvement of the epithelium and the damage is isolated to the epidermal later. The injured area is erythematous but without blistering or other skin changes. After several days, the skin may desquamate, or peel, as the cells regenerate; it will typically heal on its own within a few days, not requiring anything more than supportive therapy and rarely leaving a scar. The classic example of this type of burn is a sunburn.

• Partial-thickness burns are subcategorized into superficial partial-thickness or deep partial-thickness . Superficial partial-thickness burns are characterized by intact sensation, including light touch and proprioception, as well as pain; associated pain may be quite severe. These burns blanch and weeping and blistering are common, typically involving serous fluid. These burn wounds take longer to heal, up to 2 or 3 weeks. Fortunately, these burns are infrequently associated with contractures or hypertrophic scarring; therefore, surgical excision or skin grafting is not typically required. Deep partial-thickness burns have variable sensation. Sensation to light touch may remain intact, as well as vibration and various forms of pressure as well as stretch; however, sensation to pain is typically diminished or absent. These burn wounds may appear pink or white due to underlying vascular damage, and they will either blanch poorly or not at all.

• Full-thickness burns penetrate beyond the dermis and into the subcutaneous tissue. Dermal tissue is permanently destroyed and therefore cannot be regenerated. Nerve endings are also destroyed, so these wounds are insensate, and therefore painless. Wounds can vary in appearance from white to pink to brown and leathery or black eschar.

2

What degrees of burns are included when estimating the body surface area involved?

Superficial or first-degree burns should not be included in the measurement of estimated total body surface area (TBSA). All higher degrees of burn are incorporated into the estimated TBSA. As noted earlier, superficial or first-degree burns do not extend beyond the epidermal layer; therefore, none of the pathophysiologic responses seen with deeper burns occurs since the epithelial layer and deeper structures are not damaged. Overestimating TBSA can lead to overutilization of resources, overaggressive intravenous fluid resuscitation, and unnecessary transport to a burn center when a closer facility may have been appropriate, factors all relevant to the prehospital setting.

It is also important to ensure that soot, dirt, and other debris are cleansed from the patient, if possible, so as to not incorporate this into the estimate.

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How can you estimate the percentage body surface area involved in adult burn patients?

There is a “Rule of Nines” used to estimate TBSA for burn injuries in adults. This is perhaps the easiest estimate and works well for large contiguous areas. All major sections of the body are multiples of nine, except for the perineum:

• Head—anterior and posterior = 9%

• Right upper extremity—anterior and posterior = 9%

• Left upper extremity—anterior and posterior = 9%

• Right lower extremity—anterior = 9%, posterior = 9%, or total = 18%

• Left lower extremity—anterior = 9%, posterior = 9%, or total = 18%

• Torso—anterior = 18%

• Torso—posterior = 18%

• Perineum = 1%

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