Burn

Burn
Classification and external resources
Second-degree burn of the hand
ICD-10	T20.-T31.
ICD-9	940-949
MeSH	D002056

A burn is a type of injury to the skin caused by heat, electricity, chemicals, light, radiation or friction.^[1][2][3] Most burns only affect the skin (epidermal tissue and dermis). Rarely deeper tissues, such as muscle, bone, and blood vessels can also be injured. Managing burns is important because they are common, painful and can result in disfiguring and disabling scarring. Burns can be complicated by shock, infection, multiple organ dysfunction syndrome, electrolyte imbalance and respiratory distress. Large burns can be fatal, but modern treatments, developed in the last 60 years, have significantly improved the prognosis of such burns, especially in children and young adults.^[4][5]

Contents 1 Classification 1.1 By degree 1.2 Other classifications 1.3 Burn surface area 2 Causes 2.1 Chemical burn 2.2 Electrical burn 2.3 Radiation burn 2.4 Scalding 3 Management 3.1 First Aid 3.2 Intravenous fluids 3.3 Wound management 3.4 Antibiotics 3.5 Analgesics 3.6 Alternative treatments 4 Prognosis 5 Epidemiology 6 See also 7 References 8 Further reading 9 External links

Classification

A number of different classification systems exist. The traditional system divided burns in first-, second-, or third-degree.^[6] This system is however being replaced by one reflecting the need for surgical intervention. The burn depths are described as either superficial, superficial partial-thickness, deep partial-thickness, or full-thickness.^[7]

The following are brief descriptions of these classes:

By degree

• First-degree burns are usually limited to redness (erythema), a white plaque and minor pain at the site of injury. These burns involve only the epidermis. Most sunburns can be included as first-degree burns.
• Second-degree burns manifest as erythema with superficial blistering of the skin, and can involve more or less pain depending on the level of nerve involvement. Second-degree burns involve the superficial (papillary) dermis and may also involve the deep (reticular) dermis layer. Deep dermal burns usually take more than three weeks to heal and should be seen by a surgeon familiar with burn care, as in some cases severe hypertrophic scarring can result. Burns that require more than three weeks to heal are often excised and skin grafted for best result.
• Third-degree burns occur when the epidermis is lost with damage to the subcutaneous tissue. Burn victims will exhibit charring and extreme damage of the epidermis, and sometimes hard eschar will be present. Third-degree burns result in scarring and victims will also exhibit the loss of hair shafts and keratin. These burns may require grafting. These burns are not painful, as all the nerves have been damaged by the burn and are not sending pain signals; however, all third-degree burns are surrounded by first and second-degree burns.

Other classifications

A newer classification of "Superficial Thickness", "Partial Thickness" (which is divided into superficial and deep categories) and "Full Thickness" relates more precisely to the epidermis, dermis and subcutaneous layers of skin and is used to guide treatment and predict outcome.

A description of the traditional and current classifications of burns.

Nomenclature	Traditional nomenclature	Depth	Clinical findings	Example
Superficial thickness	first degree	Epidermis involvement	Erythema, significant pain, lack of blisters
Partial thickness – superficial	second degree	Superficial (papillary) dermis	Blisters, clear fluid, and pain
Partial thickness – deep	third degree	Deep (reticular) dermis	Whiter appearance or fixed red staining (no blanching), reduced sensation
Full thickness	fourth degree*	Epidermis, Dermis, and complete destruction to subcutaneous fat, eschar formation and minimal pain, requires skin grafts	Charred or leathery, thrombosed blood vessels, insensate

* It should however be noted that although fourth-degree is not a technical term, it is often used to describe burns that reach muscle and bone. Third-degree sufficiently describes all burns of this nature.

An even simpler, more accurate and more descriptive classification is epidermal, dermal and full thickness. Dermal injuries are subdivided into superficial, mid and deep.

It is most common for high percentage burns to only be classified as Superficial, Partial thickness and Full Thickness. The reasoning behind this is that in an emergency setting such as a burn trauma room or ambulance it is more important to protect the patient from dehydration, hypothermia and infection rather than calculating the exact depth of a burn.

Burn surface area

Burns can also be assessed in terms of total body surface area (TBSA), which is the percentage affected by partial thickness or full thickness burns (erythema/superficial thickness burns are not counted). The rule of nines is used as a quick and useful way to estimate the affected TBSA. More accurate estimation can be made using Lund & Browder charts which take into account the different proportions of body parts in adults and children.^[8] The size of the patient's hand print (palm and fingers) is approximately 1% of their TBSA. The actual mean surface area is 0.8% so using 1% will slightly over estimate the size.^[9] Burns of 10% in children or 15% in adults (or greater) are potentially life threatening injuries (because of the risk of hypovolaemic shock) and should have formal fluid resuscitation and monitoring in a burns unit.

Causes

Burns are caused by a wide variety of substances and external sources such as exposure to chemicals, friction, electricity, radiation, and heat.

Chemical burn

Most chemicals that cause severe chemical burns are strong acids or bases.^[10] Chemical burns can be caused by caustic chemical compounds such as sodium hydroxide or silver nitrate, and acids such as sulfuric acid.^[11] Hydrofluoric acid can cause damage down to the bone and its burns are sometimes not immediately evident.^[12]

Electrical burn

Electrical burns are caused by either an exogenous electric shock or an uncontrolled short circuit. (A burn from a hot, electrified heating element is not considered an electrical burn.) Common occurrences of electrical burns include workplace injuries, or being defibrillated or cardioverted without a conductive gel. Lightning is also a rare cause of electrical burns. Since normal physiology involves a vast number of applications of electrical forces, ranging from neuromuscular signaling to coordination of wound healing, biological systems are very vulnerable to application of supraphysiologic electric fields. Some electrocutions produce no external burns at all, as very little current is required to cause fibrillation of the heart muscle. Therefore, even when the injury does not involve any visible tissue damage, electrical shock survivors may experience significant internal injury.^[13] The internal injuries sustained may be disproportionate to the size of the burns seen (if any), and the extent of the damage is not always obvious. Such injuries may lead to cardiac arrhythmias, cardiac arrest, and unexpected falls with resultant fractures.^[14]

Radiation burn

Radiation burns are caused by protracted exposure to UV light (as from the sun), tanning booths, radiation therapy (as patients who are undergoing cancer therapy), sunlamps, radioactive fallout, and X-rays. By far the most common burn associated with radiation is sun exposure, specifically two wavelengths of light UVA, and UVB, the latter being more dangerous. Tanning booths also emit these wavelengths and may cause similar damage to the skin such as irritation, redness, swelling, and inflammation. More severe cases of sun burn result in what is known as sun poisoning. Microwave burns are caused by the thermal effects of microwave radiation.

Scalding

Scalding is caused by hot liquids (water or oil) or gases (steam), most commonly occurring from exposure to high temperature tap water in baths or showers or spilled hot drinks.^[15] A so called immersion burn is created when an extremity is held under the surface of hot water, and is a common form of burn seen in child abuse.^[16] A blister is a "bubble" in the skin filled with serous fluid as part of the body's reaction to the heat and nerve damage. The blister "roof" is dead. Steam is a common gas that causes scalds. The injury is usually regional and usually does not cause death. More damage can be caused if hot liquids enter an orifice. However, deaths have occurred in more unusual circumstances, such as when people have accidentally broken a steam pipe. The demographics that are of the highest risk to suffering from scalding are young children, with their delicate skin, and the elderly over 65 years of age.

Management

Burns over 10% in children and 15% in adults need hospital admission and fluid resuscitation due to the risk of hypovolaemic shock.^[17] Most countries have explicit criteria for the transfer and management of burns patients. Major burns should be managed using the principles of Advanced Trauma Life Support (ATLS). This consists of a primary survey to identify and treat immediately life threatening conditions and then a secondary survey. The primary survey in burns patients should follow the ABCDE guidelines (Airway & axial spine control, Breathing & ventilation, Circulation and arrest of haemorrhage, neurological Disability, Exposure to allow accurate assessment and Estimation of burn surface area and Fluid resuscitation). If the patient was involved in a fire accident in an enclosed space, then it must be assumed that he or she has sustained an inhalation injury until proven otherwise, and treatment should be managed accordingly. At this stage of management, it is also critical to assess the airway status. Any suspicion of burn injury to the lungs (e.g. through smoke inhalation) is considered a potential medical emergency and the patient should be reviewed by an anaesthetist. Patients with these types of injuries may receive Rapid Sequence Induction, either in the field by a trained Paramedic, or in the hospital upon arrival.

First Aid

Regardless of the cause, the first step in managing a person with a burn is to stop the burning process at the source, and cool the burn wound (but not the patient. It is essential to avoid the "lethal triad" of hypothermia, acidosis and coagulopathy).^[18] For instance, with dry powder burns, the powder should be brushed off first. With other burns the affected area should be rinsed thoroughly with a large amount of clean water. Cold water should not be applied to a person with extensive burns for a prolonged period (greater than 20 minutes), however, as it may result in hypothermia. Do not directly apply ice to a burn wound as it may compound the injury. Iced water, creams, or greasy substances such as butter, should not be applied either.^[19]

To help ease pain people may be placed in a special burn recovery bed which evenly distributes body weight and helps to prevent painful pressure points and bed sores. Survival and outcome of severe burn injuries is remarkably improved if the patient is treated in a specialized burn center/unit rather than a hospital.

Intravenous fluids

Children with TBSA >10% and adults with TBSA > 15% need formal fluid resuscitation and monitoring (blood pressure, pulse rate, temperature and urine output).^[20] Once the burning process has been stopped, the patient should be volume resuscitated according to the Parkland formula . This formula is 4 ml lactated ringers/kg x % of Total body surface area burned, with half this volume given in the first 8 hours. Children also require the addition of maintenance fluid volume. Such injuries can disturb a person's osmotic balance. This formula dictates the amount of Lactated Ringer's solution or Hartmann's Solution^[21] to deliver in the first twenty four hours after time of injury. This formula excludes first degree burns, so erythemia alone is discounted. Half of the fluid should be given in the first eight hours post injury and the rest in the subsequent sixteen hours. Inhalation injuries in conjunction with thermal burns initially require up to 40–50% more fluid. The formula is a guide only and infusions must be tailored to the urine output and central venous pressure. Inadequate fluid resuscitation causes renal failure and death but over-resuscitation also causes morbidity and mortality. All resuscitation formulae should be delivered as a goal directed therapy to prevent the complications of hypovolaemic shock or over-hydration.

Wound management

The key to the management of all burn injuries is the management of the burn wound itself. The wound is the cause of the morbidity and mortality of burn injuries and until the wound is healed the patient remains at risk of complications. The essential aspects of wound management are an initial assessment, to determine burn area and depth, and then debridement (removing devitalised tissue and contamination), cleaning and then dressings. Burn wounds are painful so analgesia (pain relief) should be given. The management of burns over 10% in children and 15% in adults, and of important areas (hands, face and perineum) is more complex and requires specialist help. Circumferential burns of digits, limbs or the chest may need urgent surgical release of the burnt skin (escharotomy) to prevent problems with distal circulation or ventilation. The wound should then be regularly re-evaluated until it is healed. Wounds requiring surgical closure with skin grafts or flaps should be dealt with as early as possible. One of the major advances in burn care has been the early excision and skin grafting of full thickness and deep-dermal burn wounds.^[3]

In the management of first and second degree burns little quality evidence exists to determine which type of dressing should be used.^[22] Silver sulfadiazine (Flamazine) is not recommended as it potentially prolongs healing time^[22] while biosynthetic dressings may speed healing.^[23]

Antibiotics

Intravenous antibiotics may improve survival in those with large severe burns however due to the poor quality of the evidence routine use is not currently recommended.^[24]

Analgesics

A number of different options are used for pain management. These include simple analgesics ( such as ibuprofen and acetaminophen ) and narcotics. A local anesthetic may help in managing pain of minor first-degree and second-degree burns.^[25]

Alternative treatments

Hyperbaric oxygenation has not been shown to be a useful adjunct to traditional treatments.^[26] Honey has been used since ancient times to aid wound healing and may be beneficial in first and second degree burns, but may cause infection.^[27]

Prognosis

The outcome of any injury or disease depends on three things: the nature of the injury, the nature of the patient and the treatment available. In terms of injury factors in burns the prognosis depends primarily on the burn surface area (% TBSA) and the age of the patient. The presence of smoke inhalation injury, other significant injuries such as long bone fractures and serious co-morbidities (heart disease, diabetes, psychiatric illness, suicidal intent etc.) will also adversely influence prognosis. Advances in resuscitation, surgical management, control of infection, control of the hyper-metabolic response and rehabilitation have resulted in dramatic improvements in burn mortality and morbidity in the last 60 years. Following a major burn injury, heart rate and peripheral vascular resistance increase. This is due to the release of catecholamines from injured tissues, and the relative hypovolemia that occurs from fluid volume shifts. Initially cardiac output decreases. At approximately 24 hours after burn injuries (for patients receiving fluid resuscitation) cardiac output returns to normal, then increases to meet the hypermetabolic needs of the body.

Infection is a major complication of burns. Infection is linked to impaired resistance from disruption of the skin's mechanical integrity and generalized immune suppression. The skin barrier is replaced by eschar. This moist, protein rich avascular environment encourages microbial growth. Migration of immune cells is hampered, and there is a release of intermediaries that impede the immune response. Eschar also restricts distribution of systemically administered antibiotics because of its avascularity.

Risk factors of burn wound infection include:

• Burn > 30% TBS
• Full-thickness burn
• Extremes in age (very young, very old)
• Preexisting disease e.g. diabetes
• Virulence and antibiotic resistance of colonizing organism
• Failed skin graft
• Improper initial burn wound care
• Prolonged open burn wound

Burn wounds are prone to tetanus. A tetanus booster shot is required if individual has not been immunized within the last 5 years.

Circumferential burns of extremities may compromise circulation. Elevation of limb may help to prevent dependent edema. An Escharotomy may be required.

Acute Tubular Necrosis of the kidneys can be caused by myoglobin and hemoglobin released from damaged muscles and red blood cells. This is common in electrical burns or crush injuries where adequate fluid resuscitation has not been achieved.

Epidemiology

In 1991, burns led to 5,500 deaths in the United States.^[29] In India about 700,000 patients a year are admitted to hospital, though very few are looked after in specialist burn units.^[30] About 90% of burns occur in the developing world and 70% of these are in children. Survival of injuries greater than 40% TBSA is rare in the developing world.^[31]

See also

• List of burn centers in the United States

References

Further reading

Herndon, David (2007). Total Burn Care. Saunders. ISBN 978-1-4160-3274-8. 

External links

• Alisa Ann Ruch Burn Foundation
• NHS Choices - Burns and Scalds
• After the Injury- Children's Hospital Of Philadelphia
• British Burn Association
• American Burn Association
• European Burn Association
• eMedicine Thermal burns article
• The UK National Burn Care Government Review
• Changing Faces - UK charity for people with disfigurement
• Total Burn Care:Website of the world's most famous Children's Burn Unit
• Burn Survivors Online USA
• Cool The Burn USA
• Burnsurgery USA
• Burn articles in the Indian Journal of Plastic Surgery
• Website for St Andrew's Centre, Chelmsford, Essex :the largest Burns Unit in England

General wounds and injuries (T08-T35, 870-949) General Wound/ trauma Blunt trauma/ superficial/closed Abrasion (Avulsion) Blister (Blood blister) Bruise/Hematoma/Ecchymosis (Battle's sign, Raccoon eyes, Black eye, Subungual hematoma, Cullen's sign, Grey Turner's sign, Retroperitoneal hemorrhage) Animal bite: Insect bite · Spider bite Penetrating trauma/open Animal bite: Snakebite · Lizard bite Ballistic trauma Foreign body In alimentary tract (Bezoar) Other Burn/Corrosion/Chemical burn · Frostbite · Traumatic amputation By region Hand injury · Head injury · Chest trauma · Abdominal trauma : INT, SF, LCT anat//devp noco(i,,d,q,u,,p,,,v)/cong/tumr(n,e,d), sysi/ proc, drug (/3/4/5/8)