Wallace Rule of Nines

The Wallace Rule of Nines calculator computes the percent of a Body Surface Area that is burned based on the Wallace Rule of Nines. Burn Percentage 

INSTRUCTIONS:  Enter the following estimated percentages:

• (H)  % of the head burned.
• (LA)  % of the left arm burned.
• (RA)  % of the right arm burned.
• (C)  % of the chest burned.
• (A)  % of the abdomen burned.
• (B)  % of the back burned.
• (G)  % of the groin burned.
• (LL)  % of the left leg burned.
• (RL)  % of the right leg burned.

Percent BSA (%BSA):  The calculator returns the percent of the burned Body Surface Area.

Burn Surface Area

The Wallace Rule of Nines can be used to approximate the percent of a patient that is burned.   It applies a percent of Body Surface Area, often a multiple of 9, for different body parts as follows:

• (9%) Entire head
• (9%) Complete left arm
• (9%) Complete right arm
• (9%) Entire chest
• (9%) Entire abdomen
• (18%) Complete back
• (1%) Groin
• (18%) Complete left leg
• (18%) Complete right leg

Example

If you compute the body surface area of a person using one of the standard body surface area methods  (e.g. Takahira Body Surface Area) and get a BSA of 2 square meters, and then note that the patient’s skin issue (e.g. burn) is on half (50%) of his chest and all (100%) of an arm, you can use the Wallace Rule of Nine as follows:

• Burn Area on Chest = 50% * 9% * 2 square meters = 0.09 square meters
• Burn Area on Arm = 100% * 9% * 2 square meters = 0.18 square meters
• Total Burn Area = 0.09 + 0.18 = 0.27 square meters of skin

This Wallace Rule of Nines Calculator makes the process simpler.   In this example, you would enter 50% for the chest and 100% for the arm.  The calculator would return 13.5%.  That's the total estimate of the body surface area that is burned.  You then multiply 13.5% times 2 square meters to get 0.27 square meters of burned skin.

Body Surface Area (BSA) is the measured or calculated surface area of a human body frequently used in physiology and medicine. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Estimation of BSA is simpler than many measures of volume.

Demographic BSA Means

Body Surface Area (BSA) Calculators

• Mosteller formula Body Surface Area Calculator
• Gehan and George formula Body Surface Area Calculator
• Boyd formula Body Surface Area Calculator
• DuBois formula Body Surface Area Calculator
• Haycock formula Body Surface Area Calculator
• Fujimoto formula Body Surface Area Calculator
• Takahira formula Body Surface Area Calculator
• Costeff formula Body Surface Area Calculator
• Wang Hihara Body Surface Area Calculator
• Schlick Body Surface Area Calculator
• Body Surface Area Comparison with Averages

Other BSA Applications

• The BSA Compare function lets you enter a body surface area and choose a demographic (above) to compute the percent compared to the mean.
• Wallace Rule of Nines:  This computes a percentage of the human body for burn victims based on percentages allocated to different body parts.
• Rule of Fives: This computes a percentage of the human body for obese burn victims.
• Parkland Replacement Fluid: This compute the volume of replacement fluids needed in the first 24 hours based on the patients weight (mass) and the percent of their body that has been burned.
• BSA Percent: This computes a body surface area based on the total body surface area and a percent..

References:

• Image of Human Body from OpenStax College.  Used through CC 3.0.  Source Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013.

Dedication:  For Scout.