
A burn injury to the entire back is 18% TBSA in an adult
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The extent of injury is best described using the percentage of the total body surface area (%TBSA) that is affected by a burn. The measurement of burn surface area is important during the initial management of people with burns for estimating fluid requirements and determining need for transfer to a burns service.
The methods for estimating TBSA are:
- The Wallace Rule of Nines (Adults Only)
- The Lund Browder (paediatrics and adults), or this websites version: Paediatric Burns Surface Area Assessment,
- Palmar Method (Hand Surface)
Several studies have compared the various methods of estimating burn surface. The Lund Browder charts are more accurate than either the Rule of Nines or palm size in identifying TBSA. The Rule of Nines is faster and more convenient to use for adult burn patients in emergency situations, however, it is not accurate for children or for obese people.

Bilateral circumferential leg burns is a 36%TBSA burn in an adult
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Tips:
- With severe burn injuries (>50%TBSA) it maybe easier to calculate what isn’t burnt then subtract it from 100 to get %TBSA burns
- Use the Palmar method to calculate %TBSA for smaller burns. Palmar method uses the size of the patients hand (palm and fingers) to estimate burn size. Remember to always use the patients hand, not the clinicians.
- In the prehospital and emergency department setting, the %TBSA burns is more important than the depth of burn. %TBSA burns has indications for severity of injury, fluid resuscitation and transfer destination. Depth of burn becomes more significant after arrival at the Burn Service as depth of burn will determine whether the burn can heal without surgical intervention, and how the Burn Service will subsequently manage it.
- If %TBSA burn estimation is inaccurate it has the potential to negatively impact fluid resuscitation by providing too much or too little fluid. Always titrate fluid resuscitation volumes according to resuscitation end points. Urine output is a simple and easy method to assess perfusion

A burn involving half the chest & 3/4 of the arm is at approx 16%TBSA
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