In order to calculate the extension of burns in adults, it is necessary to use a special diagram, such as the Tennison and Pulaski table, commonly known as the “Rule of Nines”. In children the Lund and Browder table is used because it has more detail in quantifying, and in varying the percentage of the body segments, which change with age (i.e. head and limbs).

The lesion’s clinical characteristics may be suggestive of the depth of tissue damage:

First Degree Burs
They are red, dry and very painful. The lesion is very superficial and regenerates in a period of one week without leaving a scar. The most common example is a sun burn.

Superficial Second Degree Burns
Blisters are present; they are humid and very painful. When the blisters rupture, there is an underlying pinkish or bright red bed. The lesion involves the superficial (papillar) layer of the dermis; it regenerates in a period of 8 to 14 days without leaving a scar. Hot liquids of low density cause this type of lesion.

Deep Second Degree Burns
These burns are painful. They are humid in appearance, with pinkish, deep red or grayish beds. The lesion involves the deep (reticular) layer of the dermis and heals from the cutaneous attachments (hair follicles, sweat glands and fat glands). They may become infected with ease; this is why they may deepen. They may regenerate in a period of 21 days of the local conditions are optimal, but they leave hypertrophic scars. Liquids of higher density may cause these types of lesions.

Third Degree Burns
These burns are dry, depressed and insensitive. The trajectory of the superficial thrombosed vessels may be evident through the eschar. The lesion involves the whole thickness of the skin and may not regenerate because there are no cutaneous elements from which to do so. 

It is necessary to cover the lesions by means of skin grafts. Burns caused by electricity, fire and chemicals may cause these type of lesions.

BURNS CAUSED BY LOW DENSITY LIQUIDS
They are produced by boiling water or milk. They are the most common and frequently present in patients of early or greater ages (children and senior citizens).

BURNS CAUSED BY HIGH DENSITY LIQUIDS
Typical examples of these liquids are eggnog, broths, and oils.

BURNS CAUSED BY FIRE
FLAMING is caused by a ravaging flame. They are frequent; in the home a common cause is the water heater or the stove. 

DIRECT FIRE due to the combustion of clothing produces deep burns because heat is maintained for a longer time period.

CHEMICAL BURNS
Chemical burns are caused by ACIDS or ALCALIS (substances of acid or base pH). They are not frequent and usually present in adults in their work environment or in children in their home because of carelessness with the storage and handling of these substances. They are deep burns and may reach the third degree (total thickness) because heat is maintained for a longer time, depending on the concentration of the chemical involved. Contact with the substance should be interrupted immediately, because once the contact is established, the chemical continues to burn the tissues until the substances are removed or diluted. 
This is managed by intensive washing with abundant cold running water in order to dilute the substance as much as possible.

ELECTRICAL BURNS
THE ELECTRICAL SPARK is produced by ravaging fire which is caused by current originating from an electric source. THE VOLTAIC ARCH is caused by the closure of an electric circle between the source and the human body. The lesions are superficial with respect to the spark and superficial and deep with respect to the arch. Their appearance is comparable to a lunar surface because of the continuous leaps of the electric current from one point in the skin to another. They are deeper and have a carbonized aspect where the electric current enters the skin due to the destruction of skin, fat, muscle and even bone. In many cases it is necessary to amputate the affected segment or segments.

BURNS CAUSED BY COMBUSTION OF HYDROCARBONS
These burns are conditioned by the combustion of gasoline, thinner, alcohol, etc., directly on the skin. They produce deep burns because heat is maintained on the skin by the burning hydrocarbon and clothing for a longer time period.

BURNS CAUSED BY DEFLAGRATION
These burns are produced by combustion or explosion of gun powder or dynamite. They are deep burns due to the thermal effect of the combustible material which burns in the skins surface and clothing.

BESIDES THEIR COMPLICATIONS, BURNS ARE LIFE THREATENING. THIS IS WHY INDIVIDUALS WITH THESE TYPES OF LESIONS SHOULD BE IMMEDIATELY SENT TO A HOSPITAL THAT TREATS THIS PATHOLOGY. IT IS IMPERATIVE THAT BURNS BE TREATED ADEQUATELY FROM THE INITIAL STAGES OF THE LESION.