Burn Extent Calculation

A burned adult's entire back represents 18% TBSA — but that same area on a toddler is closer to 16%. Using the wrong chart on the wrong patient changes every downstream decision, starting with fluid resuscitation.

Total body surface area (TBSA) burned drives fluid resuscitation calculations, transfer criteria, and mortality estimates, so accurate estimation is a critical first nursing assessment. The Rule of Nines divides the adult body into regions of 9% or multiples: each arm 9%, each leg 18%, anterior trunk 18%, posterior trunk 18%, head 9%, and perineum 1%. For rapid bedside estimates in adults, this is the standard. However, children have proportionally larger heads and smaller legs. An infant's head is 18% (double the adult value), while each leg is only about 14%. The Lund-Browder chart adjusts percentages by age and is the most accurate method for pediatric burns. For scattered or irregular burns, the patient's own palm (including fingers) represents approximately 1% TBSA — useful for estimating small or patchy areas. Only second-degree (partial-thickness) and third-degree (full-thickness) burns are counted toward TBSA; superficial (first-degree) burns like sunburn are excluded from the calculation. Document the percentage immediately — the Parkland formula and transfer decisions depend on this number.

Key Distinctions

Students often include first-degree burns in TBSA — only partial-thickness and full-thickness burns count. Don't apply the adult Rule of Nines to children; an infant's head is 18%, not 9%, and legs are smaller proportionally. The palm method estimates 1% TBSA using the patient's palm, not the nurse's hand — patient body size matters.

Clinical Pearl

Nine lives for adults, Lund-Browder for little ones. If the patient is under 10 years old, put down the Rule of Nines and pick up the age-adjusted chart.