Burns Overview

Original Editor - Olajumoke Ogunleye

Top Contributors - Olajumoke Ogunleye, Jess Bell, Carin Hunter, Ahmed M Diab, Naomi O'Reilly and Chelsea Mclene  

Introduction

Burn is an injury to the skin or other organic tissue primarily caused by exposure to heat or other causative agents (radiation, electricity, chemicals) (WHO). According to WHO, it is a  global public health problem, accounting for an estimated 180,000 deaths annually. It is among the leading causes of disability in low and middle-income countries and almost two-thirds occur in the WHO African and South-East Asia regions. Burns does not only affect the skin, it can have other effects on the tissue, organ and system networks such as smoke inhalation, as well as a psychological effect. It affects all gender although females have slightly higher rates of death from burn compared to males. It affects all age group and it is the fifth most common cause of non-fatal childhood injuries.

Types of burns

1. Electrical burn injury- Electrical burn injury is caused by heat that is generated when the electrical energy passes through the body causing deep tissue injury. The magnitude of the injury depends on the pathway of the current, the resistance of the current flow through the tissues, the strength, and the duration of the current flow. The different types of current causes various degrees of injury. For example, alternating current is more dangerous than the direct current and it is often associated with cardiac arrest, ventricular fibrillation, and tetanic muscle contractions.
2. Thermal burn injury- Thermal burn injuries are caused by external heat sources (hot or cold) scalds (hot liquids), as a result of energy transfer. hot solid objects, steam and cold objects. The types of thermal burns are:

• Scalds- Scald burns injury results in about 70% of burns in children. They also often occur in elderly people. The common mechanisms are spilling hot drinks or liquids or being exposed to hot bathing water. Scalds tend to cause superficial to superficial partial burns.

• Flame- Flame comprises 50% of adult burns. They are often associated with inhalational injury and other concomitant trauma. Flame burns tend to be deep dermal or full-thickness.

• Contact burn- In order to get a burn from direct contact, the object touched must either have been extremely hot or the contact was long. These types of burns are commonly seen in people with epilepsy or those who misuse alcohol or drugs. They are also seen in elderly people after a loss of consciousness; such a presentation requires a full investigation as to the cause of the blackout. Contact burns tend to be deep dermal or full-thickness.
• Frostbite- It occurs when the skin is exposed to cold for a long time causing the freezing of the skin or other underlying tissue. It is due to direct cellular injury from the crystallization of water in tissue and indirect injury from ischemia.

3. Chemical burn injury- Chemical burn injury is caused by tissue contact with chemical agents such as strong acids, alkaline, or organic compounds. Chemical agents depending on the duration of exposure and the nature of the agent have different effects on the skin. For example, contact with acid causes coagulation necrosis of the tissue (whereby the architecture of the dead tissue can be preserved), while alkaline burns generate liquefaction necrosis (whereby the tissue is transformed into a liquid, viscous mass). Systemic absorption of some chemicals is life-threatening, and local damage can include the full thickness of skin and underlying tissues.

4. Radiation burn injury- Radiation burn is damage to the skin or other biological tissue and organs due to prolonged exposure to radiation. It is the least common burn injury and the most common type of radiation burn is the sunburn caused by prolonged exposure to Ultraviolet rays (UV). Other causes are associated with the use of ionizing radiation in industry, high exposure to radiotherapy e.g. X-ray, and nuclear energy. . Radiation burns are often associated with cancer due to the ability of ionizing radiation to interact with and damage DNA.

Classifications of burns

Burns can be classified according to their severity, depth, and size of the burn.

Classification according to depth are:

• Superficial thickness or First-degree burns- Superficial thickness burns are burns that affect the epidermis only and is characterized by redness, pain, dryness, and with no blisters. Mild sunburn is an example of a superficial thickness burn.

• Partial-thickness or Second-degree burns- These burns involve the epidermis and a portion of the dermis. Partial-thickness burns are often broken down into two types, superficial partial-thickness burns, and deep partial-thickness burns.

• Superficial partial-thickness- Partial-thickness burns involve the epidermis and part for the dermis layer of the skin. Superficial partial-thickness burns extend through the epidermis down into the papillary, or superficial, a layer of the dermis. The injured site become erythematous because the dermal tissue has become inflamed. When pressure is applied to the reddened area. The area will blanch but will demonstrate rapid capillary refill upon release of the pressure.

• Deep partial-thickness burns- These burns extend deeper into the dermis and cause damage to the hair follicle and glandular tissue. They are painful to pressure, form blister, are wet, waxy, or dry, and may appear ivory or pearly white.

• Full-thickness burns (third-degree) burns-  It extends through the full dermis and often affects the underlying subcutaneous tissue. Skin appearance can vary from waxy white to leathery grey to charred and black. The skin is dry and inelastic and does not blanch to pressure, it is not typically painful due to the damage to the nerve endings. The dead and the denatured skin (eschar) are removed to aid healing and scarring is usually severe. Full-thickness burns cannot heal without surgery.

• Subdermal or Fourth-degree burns- These involve injury to the deeper tissues, such as muscle or bone and it is often blackened frequently leads to loss of the burned part.

Classification according to size

Burn size is determined by one of the three techniques: The Rule of Nine, The Lund-Browder Method, The Palmar Surface.

The Rule of Nine- This method is also known as the Wallace Rule of Nines because it is named after Dr. Alexander Wallace the surgeon who first publish the method. The Rule of Nine is used to estimate the total body surface area (TBSA) involved in burn patients and also used to estimate fluid resuscitation required by a burn patient. The body surface estimation is by assigning percentages to different body areas.

Body part	Percentage
Head and neck	9%
Anterior trunk	18%
Posterior trunk	18%
Lower extremity	18% each
Upper extremity	9% each
Groin	1%

Lund- Browder method- This method is used instead of Rule of Nine for assessing the total surface area affected in children. Different percentages are used because the ratio of the combined surface area of the head and neck of the surface area of the limbs is typically larger in children than in adults.

Palmar Surface method- The palmar surface can be used to estimate relatively small burns or large burns. But for medium size burns, it is inaccurate. The surface area of a patient’s palm including the fingers is used to calculate the TBSA.

Pathophysiology of burns

Burn injury depending on the severity of the injury can result in both local and debilitating systemic effects on all other organs and systems distant to the burn area.

Local Effect

This occurs immediately after the injury and the burn wound can be divided into three zones.

• Zone of coagulation: This occurs at the point of maximum damage and this zone is characterized by irreversible tissue damage due to coagulation of the constituent proteins that occurs as a result of the insult.

• Zone of stasis or zone of ischemia: This zone lies adjacent to the zone of coagulation and it is subject to a moderate degree of damage associated with vascular leakage, elevated concentration of vasoconstrictors, and local inflammatory reactions resulting in compromised tissue perfusion. But the integrity of the tissue in this zone can be saved with proper wound care

• Zone of hyperemia: This is the outermost zone. It is characterized by the eased blood supply and inflammatory vasodilation. The tissue here will recover unless there is severe sepsis or prolong hypoperfusion.

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References

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