ASSESSMENT OF BURN SURFACE AREA……

Doc, what happens if I calculate the burn area wrongly? Is it really important?

Arthur A, Canada

As we have seen in previous posts the loss of fluid from the skin surface depends on the degree of burns and the area of the burns. One must evaluate the total burn surface area (TBSA) to calculate the fluid requirements. There are different methods of fluid calculation in burns.

a) Rule of nine

The rule of nine works well in adult patients. In this method the body surface is divided into various parts measuring in nines.

Rule of nine

Each arm - 9% TBSA

Head - 9% TBSA

Anterior thorax - 18% TBSA

Posterior thorax - 18% TBSA

Perineum - 1% TBSA

Each leg - 18% TBSA

Any burn surgeon will tell you that more often the burns are so irregularly placed that accurate calculation becomes difficult in different regions of the body. In such cases a simple trick is to use the palm of the hand as a method of calculation. At any age the palm of the hand is approximately 1% and can be used to measure the burn areas.  One must not forget that it is the patient’s hand that is used for the calculation and not the doctor’s. An approximate size of the palm of the patient is considered and the equivalent burn area is estimated. For e.g. lets say the burn area was 5 palm sizes of the patient over the body and lower limbs. Now we can assume that the patient has about 5% burns.

It should be noted that first degree burns do not produce fluid losses and therefore only 2^nd degree burns or more should be used for fluid calculation.

However in children the rule of nine can lead to serious errors as the head and body is larger in TBSA than the limbs and therefore the Lund and Browder charts work out to be more accurate while calculating the fluids to be administered.  The Lund and Browder chart is shown below. 

If the fluid calculation is wrong then the patient will be administered less fluids and this will result in shock or low volume circulatory failure and ultimately may be fatal.  The fluids calculated need to be replaced within a time limit as we shall discuss in the next post. Correct volume replacement and correct timing is what makes the resuscitation of burns patients successful.

(an original initiative in burn care and education from asktheburnsurgeon+)