ABC of wound healing: Burns

About 250 000 people are burnt each year in the United Kingdom. Of these, almost 112 000 attend an emergency department, and about 210 die of their injuries. At least 250 000 others attend their general practitioner for treatment of their injury. A burn results in loss of epidermal integrity of the skin; this article discusses the cause and management of various types of burn injury

Mechanisms of burn

Thermal injury
Flame - Accelerants such as petrol, lighter fluid, or natural gas are often involved. The depth of flame burn is typically full or partial thickness.
  Scald - 60% of burns in children are from scalds. Intentional injury is rare but should be considered if there are delays in presentation, inconsistencies in history, or an unusual pattern of injury.
  Contact - Contact burns often pres- ent as small burns on extremities, but they can be serious in those not able to remove themselves from the source of injury, such as elderly people, children, disabled people, and people incapacitated by drugs, alcohol, fit, or faint.

  Flash - Flash burns are usually to the face and upper limbs and are caused by an explosive ignition of a volatile substance. They are often due to use of accelerants to light a fire or gas explosions.

Clockwise from top left: Full thickness flame burn to the right arm, torso, and face and neck (not shown); "pullover" scald (hot tea) to a toddler; flash burn and erythema to face (note sparing of skin creases); full thickness contact burn (patient was alcoholic and fell unconscious against a portable heater)

Electrical injury
Low voltage - The energy imparted from 240 V usually gives a deep burn in the form of a small entry and exit wound. Such burns are commonly seen on the hands. If alternating current crosses the myocardium, arrhythmias may arise. If the electrocardiogram is normal and there is no history of loss of consciousness, admission to hospital for cardiac monitoring is not required.

   High voltage - High tension burns occur with an injury resulting from 1000 V or more. These catastrophic injuries result in extensive tissue damage. Rhabdomyolysis and renal failure may occur.

   Flash - An arc of high tension current from a high voltage power source may cause injury, without the current traversing the body. Heat can damage exposed skin, and clothing may ignite.

Chemical injury
Acids - Acids cause coagulative necrosis, denature proteins, and are usually painful. Hydrofluoric acid penetrates tissues deeply and can cause fatal systemic toxicity even in small burns. Immediate copious lavage and treatment with topical calcium gluconate gel is essential. Systemic calcium may be required as hydrofluoric acid sequesters calcium with the burn.

Alkalis - Common household alkalis such as bleaches, cleaning agents, and cement give a liquefactive necrosis. They have the potential to penetrate tissues deeper than most acids as further injury occurs as cells dehydrate and collagen and protein are denatured. Often the onset of pain is delayed, thus postponing first aid and allowing more tissue damage.

Burn assessment

The severity of burn injuries is related to the depth of skin involve ment and the percentage of total body surface area involved.

In the UK, burns are classified as partial thickness or full thickness, as these terms correspond to the level of burn injury and the likelihood of healing without surgical intervention.

Partial thickness burns are further categorised as superficial or deep dermal. Superficial burns usually heal without surgery, but deeper burns are likely to require excision and skin grafts. Burn depth can progress without adequate first aid and treatment such as appropriate fluid resuscitation and dressings. Burn depth can be worsened by the presence of infection. Superadded infection may lead to an increase in burn depth.

Classification of burn depth

Superficial burns
These usually heal within 14 days and leave minimal scarring. Burn erythema may be described as skin redness and pain. Erythema is not included in the assessment of

About 250 000 people are burnt each year in the United Kingdom. Of these, almost 112 000 attend an emergency department, and about 210 die of their injuries. At least 250 000 others attend their general practitioner for treatment of their injury. A burn results in loss of epidermal integrity of the skin; this article discusses the cause and management of various types of burn injury the percentage of total body surface area. With superficial dermal burns the outer part of the dermis is injured; these burns characteristically have blisters and are very painful.

Deep burns

These take a prolonged time to heal and do so with severe scarring. All but the smallest areas of full thickness burn require surgical intervention. In deep dermal burns the skin has fixed capillary staining and has a blotchy cherry red appearance. It does not blanch with pressure and is typically insensate. Full thickness burns have a leathery white or charred black appearance (eschar). In people with dark skin, parameters other than skin colour may need to be used.

Management of burn injuries

First aid
The person should be removed from the burning source without endangering the rescuers. If clothing is alight, fol- low the "drop and roll" procedure. When electricity is involved, power should be turned off before administer- ing first aid. The burn should be cooled (or the toxin diluted) with lukewarm running water for at least 20 min- utes. This period should be increased in those with chem- ical injury. Ice or very cold water should be avoided, as blood flow to the affected area will be reduced, and hypothermia induced, particularly in infants and elderly people. Patients are assessed and their treatment priorities established on the basis of the severity of their injuries. The history of events leading to the burn will also alert those treating the patient to the risks of coexisting injury. Inhalation injury is potentially life threatening when burns have been sustained in enclosed areas.

Simple analgesia or opiates should be used. Covering the burn and cooling with water will also provide some pain relief.

Dressings
Polyvinyl chloride sheeting ("clingfilm") or sterile cotton sheeting may be used initially. These are simple to use and allow wound inspection so that definitive assessment can be performed. Sterile burn cooling gels are also available.

Minor burn injury
Debridement
Burn debris should be removed with mild soap and water, sterile saline, or a topical antiseptic solution before dress- ings are applied. The dead skin of open blisters should be removed, and large or friable blisters should also be "deroofed" (the outer layer removed). Small blisters may be left intact. Antibiotics are not routinely prescribed in minor burns. The tetanus status of the patient should be checked.

Dressings
In the simple, clean, partial thickness burn, dressings such as paraffin gauze (for example, Jelonet), chlorhexidine impregnated gauze (Bactigras), or similar dressings such as soft silicone (Mepitel) or soft polymer (Urgotul) can be used with an overlying gauze pad. Hydrocolloid dressings are particularly good for use on hands and other small areas of superficial or partial thickness burns, although they leave a "skim" of exudate that needs to be removed to allow appropriate assessment of the wound. In bigger burns, several layers of dressing are usually required to absorb exudate and to prevent shear or friction of the skin.

Dressings such as alginate adhere to the wound and should be reviewed after 24 hours. At this point only the secondary dressing immediately overlying the alginate needs to be replaced. Once the wound is healed, the algi- nate separates off. If there is excessive exudate or a full thickness burn, the dressing fails to stick, indicating the necessity for further assessment. These properties also make alginate dressings useful for donor sites after skin graft harvest.

Major burn injury
A major burn should be managed according to the guide- lines advocated in the British Burn Association's Emer- gency Management of Severe Burns course. Transfer of these patients needs careful planning and communication with the burns team. In a patient with multiple injuries, the most obvious injury may be their burn, but careful assessment and treatment of other injuries is vital before burn management. All patients with facial burns or sus- pected of having inhaled smoke or hot gases should be assessed by an anaesthetist before being transferred to a specialist unit, as early intubation may be required.

Deep or full thickness burns make the skin inelastic and act like a tourniquet. They should be released by escharo- tomy to prevent respiratory embarrassment (of the chest and abdomen) or vascular compromise of the limbs. This may need to be done before transfer to a specialist unit.

Fluid resuscitation is indicated after a serious burn (=10% of total body surface area in children and =15% in adults). The British Burn Association recommends the use of the Parkland formula, but intravenous fluids should also be guided by the patient's response to resuscitation.

Surgical debridement of the major burn is influenced by the fitness of the patient to undergo a procedure and the depth and location of the burn. Excision of the burn may be required. Reconstruction is often done with split skin grafts taken from the patient in single or multiple stages. This may be combined with cadaveric skin if the patient has insufficient donor skin. Artificial skin substi- tutes are being increasingly used with good results (see a later article in this series). Several layers of dressings are used to minimise shear at the site of skin grafting. These should not be too tight as swelling often occurs after a burn injury.

Above: A Lund and Browder chart is useful in assessing the extent of burn injury (the relative proportions of body areas differ in children)

Top: Superficial dermal scald (top). Bottom: Burn injury of different depths (FT=full thickness; DD=deep dermal; SD=superficial dermal)

Above: Full thickness burns of the abdomen have been excised and closed with split thickness skin grafts.

Above: Escharotomies to the chest to allow respiratory expansion

Once a burn has healed, the area should be regularly moisturised and protected from the sun by sunblock cream or clothing. Physiotherapy may be required to prevent burn contractures. All burns are suscepti- ble to infection. Silver based products have traditionally been used to treat burns, including silver sulfadiazine (Flamazine) and silver sulfadiazine plus cerous nitrate (Flammacerium) - the latter available only on a named patient basis in the UK. However, the use of these preparations makes sub- sequent assessment difficult. Ideally, they should not be applied without discussion with the burns team.

Repeated review of the burn wound and multiple dressing changes are unnecessary. A change of dressings and wound review after 48 hours is usual. Further changes are guided by the rate of healing, but are generally needed at intervals of two to three days. More frequent change of dressing is needed if there is a high volume of exudate or evi- dence of infection.

Right: Artificial skin substitute used to cover full thickness burnPrevention of burns is key: the main improvement in reduction of burns in the UK over the past 40 years has been the introduction of legislation to reduce the flammability of clothing, furniture, and fireworks and of proper labelling of inflammable materials.

Competing interests: KGH's unit receives income from many commercial companies for research and education, and for advice. It does not support one company's products over another.

The ABC of wound healing is edited by Joseph E Grey (joseph.grey@cardiffand- vale.wales.nhs.uk), consultant physician, University Hospital of Wales, Cardiff and Vale NHS Trust, Cardiff, and hon- orary consultant in wound healing at the Wound Healing Research Unit, Cardiff University, and by Keith G Harding, director of the Wound Healing Research Unit, Cardiff University, and professor of rehabilitation medicine (wound healing) at Cardiff and Vale NHS Trust.

This ABC chapter was first published in the BMJ (2006;332:649-52).

Alex Benson, specialist registrar in plastic surgery, Mersey Regional Plastic Surgery Unit, Whiston Hospital, Liverpool

William A Dickson, consultant burns and plastic surgeon, Welsh Centre for Burns and Plastic Surgery, Morriston Hospital, Swansea
Dean E Boyce, consultant hand and plastic surgeon



studentBMJ 2006;14:309-352 September ISSN 0966-6494