What is total burn formula?

The term "total burn formula" isn't a single, universal formula but rather refers to methods used to estimate the total body surface area (TBSA) affected by burns. The most common method is the Rule of Nines, which assigns percentages to different body regions. Here's how it works, with variations for adults and children:

Rule of Nines for Adults

The Rule of Nines for adults is a quick way to estimate the TBSA affected by burns. It assigns these percentages:

Body Region	Percentage of TBSA
Each Arm	9%
Each Leg	18%
Head	9%
Front Torso	18%
Back Torso	18%
Total	100%

• Example: If an adult has burns on their entire right arm and the front of their chest, the TBSA affected would be 9% (arm) + 18% (front torso) = 27%.

Rule of Nines for Children

The Rule of Nines needs modification for children due to different body proportions. The head of a child is proportionally larger, and the legs are smaller compared to an adult. These differences are reflected in the assigned percentages:

Body Region	Percentage of TBSA
Each Arm	9%
Each Leg	14%
Head	18%
Front Torso	18%
Back Torso	18%
Total	100%

• Example: If a child has burns covering their entire head and one full arm, the TBSA would be 18% (head) + 9% (arm) = 27%.

Why is TBSA Calculation Important?

Accurately estimating TBSA is crucial because it guides crucial decisions in burn care, such as:

• Fluid resuscitation: The amount of intravenous fluids needed is often based on TBSA burned.
• Determining admission to a specialized burn center: Burns exceeding a certain TBSA percentage may require the resources of a burn center.
• Prognosis: TBSA is a factor in predicting the likely outcome for a burn patient.
• Medication dosages: The total burnt surface area can influence medication dosages.

While the Rule of Nines is commonly used for initial estimations, other methods like the Lund-Browder chart may be employed, particularly for children where body surface area distribution changes with age.