Classification of Burn injury
1. Thermal burn: Caused by flame, causing damage from superheated, oxidized air, or scald due to contact with hot objects, liquids, and steam are the most common causes of burns.
2. Cold burn: Caused by exposure to very cold air, contact to very cold objects, or even unregulated therapeutic application of ice/coolant spray.
3. Chemical burn: Caused by corrosive chemicals like acids, coming in contact with the skin, are in effect similar to thermal burns.
4. Electrical burn: Caused by the passage of high voltage electric current through the body.
5. Radiation burn: Caused by exposure to radioactive source or very bright sunlight.
Thermal, cold, and chemical burns usually affect the skin, which sustains most of the damage. However, severe surface burns may penetrate to deeper body structures, such as fat, fascia, muscle, or bone.
An electrical burn affects deeper structures such as blood vessels and nerves because these structures provide a pathway of minimum impedance for the electric current to flow.
The damage to the skin is restricted only to the points of entry and exit of the electrical current.
Radiation burns are far more insidious, affecting the vitality of the skin and the underlying tissues gradually, leading to progressive skin break down, peeling, and ulceration.
B. JACKSON'S BURN MODEL:
The skin provides a barrier to the transfer of energy to deeper tissues.
The response of local tissues to burn agents can lead to injury in the deeper layers.
The area of cutaneous injury has been divided into three zones based on Jackson's burn model:
JACKSON'S BURN MODEL:
A burn wound is a dynamic entity and is subject to the effects of secondary injury.
A burn wound may deepen if the blood supply of the wound is impaired or if infection occurs.
Jackson's model describes the distinct areas seen within every burn wound.
Central to the wound lies the zone of coagulation, which represents the zone of severe damage caused by primary injury, In the core of the wound these tissues will not recover and will slough off in due course of time.
Fig. 1: Schematic representation of zones of tissue damage in burn injury
Surrounding the zone of coagulation is the zone of stasis, which comprises of less damaged tissue surrounding the core of the wound, in which inflammation occurs and vascularity is impaired. The tissue in this zone has the potential to recover under the correct conditions.
The outer layer is the zone of hyperemia comprising of tissue with intense vasodilatation and increased blood flow. These recover spontaneously unless severely infected.
In favorable conditions, the margin of the central zone remains static and the zone of stasis shrinks as it is replaced by the zone of hyperemia.
C. Classification Based on Depth of Burn:
The depth of injury from a burn is described as first, second, third, or fourth degree, depending on the layers of skin affected from the outermost epidermis progressing deeper into the body surface:
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| Fig. 2: depth of burn |
1. First Degree Burn:
This is the most common type of burn; usually indicated by redness to the skin without blistering, pain, slight swelling of the affected area.
First-degree burns are the most superficial, affecting only the outermost layer of the skin, i.e. the epidermis.
The skin becomes painful, red, and blanches to the touch.
The usual cause of the first-degree burn is sunburn or steam burns. figure 3 shows the first-degree sunburn on the lower back, with the skin appearing blotchy red and swollen over the sacrum and steam burn over the forearm, with the skin looking red. This finding is characteristic of first-degree burns, occur- ring without blisters but with a significant amount of pain, swelling, and local tenderness.
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| Fig. 3: First-degree burn over the back and forearm |
First-degree burn injury is usually self-limiting and self-curing in nature.
It heals within a span of three to seven days.
Coldwater bath and the local application of Calamine lotion with Aloe Vera or Lidocaine gel help reduce skin irritation and pain.
Simple NSAIDs such as ibuprofen may also be given.
Prevention:
The prevention of sunburn is simple. One may use a sunblock with a minimum of SPF 30.
Cover the body as best as possible with light-colored long sleeve clothing and full pants when the sun is exceptionally hot.
2. Second Degree Burn:
A second-degree burn is indicated by redness or whiteness to the skin, intense pain, and swelling of the affected area & as well as blisters.
Second-degree burns (also called partial-thickness burns) extend into the middle layer of skin, i.e. the dermis. Second-degree burns appear pink or red, swollen, and painful, and they develop blisters that may ooze clear fluid. The burned area may blanch when touched.
Second-degree burns can range from severe sunburn to burns from flame, steam, or corrosive chemicals like acids.
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| Fig. 4: Second-degree burn of the leg with blister and palm without blisters |
Someone else becomes burned quickly flush the burned areas with lots of water. This also applies to chemical burns.
Though certain chemicals may react with water to cause burning, even so, enough water will wash off be causing the bun.
Remove any jewelry from the body as the metal can become hot and cause further burns as well.
After flushing the burned area, the wound must be quickly air-dried and covered with dry gauze.
Do not use any type of burn cream or ointment on the burn as they can actually cause harm with severe burns.
Prevention:
Prevention can be difficult due to the wide range of causes.
Caution is always advised when dealing with fire or dangerous chemicals.
Second-degree burns are further classified as:
a. Superficial partial-thickness burns:
Superficial partial-thickness burns are red, painful, and blanch to touch and often may form a blister.
It involves the entire epidermis and superficial part of the dermis, sparing patches of the stratum germinativum (layer of growing skin cells between epidermis and dermis), hair follicles, sebaceous, and sweat glands.
Healing takes place spontaneously in 7 to 14 days in absence of any secondary infections, without any scar formation The skin grows back from surviving stratum germinativum retained in epidermal structures like the skin ridges, hair follicles, and sweat glands.
b. Deep partial-thickness second-degree burn:
Deep partial-thickness second degree burns: involving both the superficial and the deep parts of the dermis, appear more pale and mottled, do not blanch to touch, and remain painful to pinprick.
These burns heal in 14 to 35 days by re-epithelialization from hair follicles and sweat gland keratinocytes, often with severe scarring as a result of the loss of dermis.
Treatment of deep partial-thickness burn consists of aggressive pain management, burn dressing, antibiotic cover, and fluid-nutrition replenishment & complimented by artificial or split skin graft to cover the raw area.
The purpose of wound cover is to minimize fluid loss, protect the delicate surviving pockets of growing skin cells from infection and external trauma and allow them to grow back to the maximum possible extent, and promote revascularization of the new skin.
3. Third Degree Burns
This is an extremely severe burn injury and requires immediate medical care.
These types of burns usually occur with explosions or fires, which are fuelled by highly inflammable chemicals such as gasoline or alcohol.
Third-degree burns, also called full-thickness burn, involve all three layers of skin (epidermis, dermis, and subcutaneous fat layers, characterized by a hard, leathery eschar that is painless and black, white, or cherry red.
These burns penetrate the dermis, nerve endings have been destroyed, and the patient has no feeling in the burned area. No epidermal or dermal appendages remain
These burns are indicated by charred black and even waxy white flesh. Blisters and redness occur typically around the edge of the burns and Sometimes can be completely pain-free within the burn area and painful only around the edges.
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| Fig. 5: Third-degree burn of the dorsal surface of the hand and both legs |
Treatment:
The initial treatment for this type of burn is the same as a second-degree burn, i.e. remove all jewelry, flush with lots and lots and lots of water, dry, and cover with dry gauze.
The victim will however need to go directly to the emergency room of a hospital with an active Burn Center.
These wounds must heal by re-epithelialization from the wound edges.
Deep dermal and full-thickness burns require eschar excision with skin grafting to heal the wounds in a timely fashion.
Fourth-degree burns or charring (Fig. 6) involves the carbonization of other tissues beneath the skin, such as muscle, bone, and brain and helps control shortness of breath.
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| Fig.6: Forth degree of burn of forearm and hand |
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