First, second, third and fourth degree burns: characteristics and methods of intervention

By Cristiano Antonino On Apr 19, 2023

If you intervene in an emergency, it is essential to know how to classify a burn, and to know how to communicate the severity. You also need to know their differences, depending on the degree

It is in fact important to be aware that a certain degree of burn will lead to a state of shock, and that this could affect heart function

A burn is an injury to the integumentary tissues (skin and skin appendages) caused by the action of heat, chemicals, electric current or radiation.

They can be of various entities according to the intensity of the temperature, the duration of the contact and the physical state of the burning substance (solid, liquid or gaseous); in relation to the severity they are divided into groups:

1) First degree burns (epidermal or superficial burn)

First-degree burns, also called epidermal or superficial, are the lightest because the lesion is limited to the most superficial layer of the skin; they determine the appearance on the skin of a simple redness (erythema) accompanied by a burning but bearable pain and heal spontaneously and quickly without leaving scars on the skin.

2) Second degree burns (dermal or partial thickness burns)

Second-degree burns, also called dermal or partial thickness, are the type of burns in which, in addition to the superficial layer of the skin, there is also an involvement of the underlying tissue layer; these burns cause intense skin inflammation, swelling and the formation of fluid-filled blisters (phlyctene), are very painful and heal very slowly. Second degree burns can be further divided into:

superficial dermal burn: it affects the epidermis and only the most superficial layer of the dermis;
intermediate dermal burn: affects epidermis and part of the dermis;
deep dermal burn: affects the epidermis and the entire underlying tissue layer with compromise of hair follicles and sweat glands.

3) Third degree burns (full thickness burn)

Third-degree burns, also called full-thickness burns, are very serious burns as there is deep tissue involvement; the skin appears blackened, cold, dry and hard, there is no pain due to the destruction of the nerve endings and healing takes a long time, leaving permanent scars which may require plastic surgery.

If the burn is particularly extensive, it can put the patient’s life at risk.

4) Fourth degree burns

Fourth-degree burns are the most invasive: they involve injuries of varying severity to deeper tissues, such as muscles or bones, often resulting in the need for amputation. Also in this type of burn, as in the third degree one, there is no pain in the affected area and, if extensive, it puts the patient’s life at risk.

Heat sources

The most common are: fire and liquids.

Others are: hot metals, toxic chemicals (this is called caustication), or high voltage electric current.

They can act by irradiation (sun rays, flames, vapours) or by direct contact (hot, flammable liquids, solid bodies, electric current).

The most frequent causes of burns are: accidents at work; domestic accidents follow (above all children and the elderly).

The causative agents of burns vary with age.

They condition the extent and severity of the thermal injury.

Surface affected by the burn

The severity of the burn is not judged only by the depth but also by the extent of the lesions and the location of the affected area.

For example, a third-degree burn that affects a very small area is less severe than a second-degree burn that affects 70% of the body surface area.

A medium-sized but very extensive burn can in fact produce greater dehydration and even hyperfunctioning of the body’s metabolism due to the great heat dispersion that occurs through the body region not covered by the destroyed skin.

Hyperfunctioning which induces catabolism of proteins and fats transformed into carbohydrates and therefore serious malnutrition problems.

For a quick calculation of the body surface affected by a burn, the “rule of 9” is often used in emergency medicine.

Other factors of gravity

In addition to the degree and extent, thirdly, the severity of a burn depends on the affected body site (areas covered with hair and a thicker skin layer protect better than hairless areas with thin skin, such as flexor surfaces and folds joints), but also by the general conditions of the injured person:

age (young children and the elderly are most at risk);
physical conditions and concomitant injuries (aggravating factors for burns are the simultaneous presence of head trauma, fractures, body dehydration);
pre-existing diseases (it is more dangerous in the presence of cardiomyopathies, bronchopneumopathies, diabetes and liver or kidney diseases).