Burn area estimation or percentage of burns.

4) Dear burn surgeon, my son-in-law who is 34 years old was admitted to hospital with 22 % burns. Doc, is this a major burn and is it life threatening?
charulata s
sri lanka+
Dear Charulata,
You have raised three important issues:
1) What does percentage burn mean?
2) Why do we need to calculate the percentage of burn?
3) How do we calculate the percentage of burn.

1. What does percentage burn mean?
If we imagine and spread out the entire skin of our body it will cover 0.2-0.3 m2 while for an adult it will cover 1.5-2.0 m2 or 1.75 square meters approximately.
If we say that the face or the chest was burnt we will not have a clear idea about how much area is burnt, hence the area of skin burnt is mentioned in percentage as a standard for comparison. The entire skin area of the body is that is burnt is referred to as TBSA or total burn surface area.

2. Why do we calculate the percentage of burns?
Calculating the percentage of burns tells us if it is a minor burn, moderate burn or a major burn.

Minor burn- less than 10% burn area in children
-less than 15% burn area in adults
-burns that do not involve the head , feet, hands or perineum (genital and anal area) are included in this group

Moderate burn- burn area of 10-25 % in children
-burn area of 15-25% in adults
-2nd degree superficial burn of head, hands, feet or perineum are also included in this group

Major burn- burn involving more than 25%TBSA
others that are included in this group:
-full thickness burns more than 10% TBSA
-deep burns of the hands, feet, head, or perineum
-patients who have inhaled a lot of toxic smoke and suffer damage to lungs (smoke inhalation injury)
-high voltage electrical burns
-chemical burns

As the percentage of burns increases, so do the problems faced with management and healing of the burn wound. With increasing are of burn, more fluid is lost from the body and replacement in the form of intravenous fluids becomes a necessity. Thus children with more than 10% burn area and adults with more than 15% burn area will need to be admitted to the hospital for intravenous fluid administration. Furthermore as the percentage of burn increases, the rate of complications, sepsis or infection and period of recovery all increase. The availability of skin for skin grafting also decreases. Thus knowing the area of burn is extremely important before we start to treat the burn itself.

3. How do we calculate the percentage of burns?
The simplest way is ‘the rule of nine’ by wallace i.e. each part of the body is 9% or multiple of nine.



Head - 9%
Each upper limb - 9%
Anterior trunk – 18%
Posterior trunk – 18%
Each lower limb – 18% x 2
Genital area – 1%
Total =100%




This works well in adults but newborn, infants and preschool children have larger head, smaller body and lower limbs. The Lund and Browder chart accurately helps to calculate the burn are in these patients.

Lund and Browder Chart






If the area of burn is small and does not include whole parts of the body one can simply use the palm of the patient as representing 1% and calculate the burn area. For e.g. five palms that cover the area of the burn will mean 5% burn.
It is important to use the palm size of the patient and not your palm size!!!!!

Therefore charulata, a 22% burn is a moderate burn and generally should not be life threatening unless there is an associated serious inhalation injury to the lungs or there is uncontrolled infection.

Dear Burn Surgeon,
Can you please tell me about the first aid for burns and how to avoid burns in general?
Susan A.
California.
Watch out for my next blog for the answer!!