How to Calculate Pediatric Burn Area

A young patient with a significant burn of the forearm -- about 2% of his total surface area.

The "Rule of Nines" has been a marvelous tool in quickly estimating the surface area involved in someone who has been severally burned, and provides an important factor in beginning fluid resusitation as quickly as possible. The rule is also easy to learn: the head and each arm are each 9% of the total body surface area; the front torso, back torso, and each leg are each 18%; and the genital area 1%. This rule, however, does not apply in children under the age of 10 years, because their body proportions are different than adults.

Instructions

1. Estimate the burned surface area of a child quick by using a modified Rule of Nines. For infants up to one year of age, assume the head is 18%, twice the area of an adult. The difference is taken from the legs, 4.5% from each, giving each leg a total of 13.5%.

2. Estimate the burned surface area of older children by using the formula: 18% - 1% x age in years for the head surface area. A five-year-old, for example, would have a head surface area of 18% - 5% = 13%. The percentage subtracted from the head, 5% in this instance, is added to the legs, now 13.5% + 2.5%, or 16%, each.

3. Estimate the surface areas of burns that cover less than an entire region by using the child's palm as about 1% of the total body surface area. You can then compare the palm size to the burned area for a quick area estimate.

Tips & Warnings

• This method is quick, but only a rough estimate to be used for initial assessments and treatments. A commercially available burn chart, such as the Lund and Browder Chart, allows a more accurate measurement of the involved area and should be used as time allows.

References

• "Physical Medicine and Board Review," Pediatric Burns, Sara J. Cuccurullo, MD, Editor, 2004
• "Burn Care Commentary," The Burn-Injured Child: Examination of Pediatric Burn Needs, S.M.A. Hassan, MD, 2006