LEARNING OBJECTIVE: Recall the classification and evaluation process for burns, and determine the appropriate treatment for each type of burn.

Under the broad category of environmental injuries, we will consider a number of emergency problems. Exposure to extremes of temperature, whether heat or cold, causes injury to skin, tissues, blood vessels, vital organs, and, in some cases, the whole body. In addition, contact with the sun's rays, electrical current, or certain chemicals causes injuries similar in character to burns.

THERMAL BURNS
True burns are generated by exposure to extreme heat that overwhelms the body's defensive mechanisms. Burns and scalds are essentially the same injury: Burns are caused by dry heat, and scalds are caused by moist heat. The seriousness of the injury can be estimated by the depth, extent, and location of the burn, the age and health of the victim, and other medical complications.

Classification of Severity
Burns are classified according to their depth as first-, second-, and third-degree burns (as shown in figure 4-47).

FIRST-DEGREE BURN.-With a first-degree burn, the epidermal layer is irritated, reddened, and tingling. The skin is sensitive to touch and blanches with pressure. Pain is mild to severe, edema is minimal, and healing usually occurs naturally within a week.

SECOND-DEGREE BURN.-A second-degree burn is characterized by epidermal blisters, mottled appearance, and a red base. Damage extends into3/4but not through the dermis. Recovery usually takes 2 to 3 weeks, with some scarring and depigmentation. This condition is painful. Body fluids may be drawn into the injured tissue, causing edema and possibly a "weeping" fluid (plasma) loss at the surface.

THIRD-DEGREE BURN.-Athird-degree burn is a full-thickness injury penetrating into muscle and fatty connective tissues, or even down to the bone. Tissues and nerves are destroyed. Shock, with blood in the urine, is likely to be present. Pain will be absent at the burn site if all the area nerve endings are destroyed, and the surrounding tissue (which is less damaged) will be painful. Tissue color will range from white (scalds) to black (charring burns). Although the wound is usually dry, body fluids will collect in the underlying tissue. If the area has not been completely cauterized, significant amounts of fluids will be lost by plasma "weeping" or by hemorrhage, thus reducing circulation volume. There is considerable scarring and possible loss of function. Skin grafts may be necessary.

Rule of Nines
Of greater importance than the depth of the burn in evaluating the seriousness of the condition is the extent of the burned area. Afirst-degree burn over 50 percent of the body surface area (BSA) may be more serious than a third-degree burn over 3 percent. The Rule of Nines is used to give a rough estimate of the surface area affected. Figure 4-48 shows how the rule is applied to adults.

Other Factors
A third factor in burn evaluation is the location of the burn. Serious burns of the head, hands, feet, or genitals will require hospitalization.

The fourth factor is the presence of any other complications, especially respiratory tract injuries or other major injuries or factors.

Figure 4-47.-Classification of burns.

Figure 4-48.-Rule of Nines.

The Corpsman must take all these factors into consideration when evaluating the condition of the burn victim, especially in a triage situation.