Burn Size

Burns are judged by the size of the burn in relation to the whole body and by the depth of the burn injury. Different methods exist to calculate the extent or size of a burn injury. The most common method, which provides a quick estimate of burn size, uses the "Rule of Nines," where the body is divided into areas equaling multiples of 9% of the total body surface area. The palm of your hand, for example, is equal to about 1% of your body's surface area. The head and arms are each equal to 9% of the body surface. The chest and back are each 18% (2 x 9%). Each leg is 18% (2 x 9%). This totals eleven nines, or 99%. The heads of infants and small children are in relatively larger proportion to the total body surface area, and the limbs are in relatively smaller proportion than adults limbs. The total body surface area of a burn is referred to as TBSA, or total body surface area. A patient might have the diagnoses of a 45% TBSA thermal burn, for example. The TBSA and burn depth analysis are recorded on a hospital chart known as a "burn diagram." Determining the percent of body surface area burned is important for correct fluid resuscitation.