Burns

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Chapter 20 Burns

Linda Dann

Skin is the largest organ in the body, approximating 15% of body weight and 4.9 square metres in an adult. It has a number of functions, which correspond to the rationale of management and the potential complications of burns:

• protection from the environment (infection)
• temperature control (hypothermia)
• fluid control (dehydration and fluid replacement)
• energy control (need for increased caloric intake in larger burns).

The majority of burns occur in the home and affect mainly young men and those at the extremes of age.

TYPES OF BURNS

• Thermal (including scalds)
• Chemical
• Electrical
• Radiation

Specific other factors

• Eyes: chemicals, flash burns, molten metal
• Extremes of age (< 5 or > 65 years)
• Airway/lung injury—blast injury may be fatal if untreated
• Hands/feet/perineum
• Circumferential burns of limbs or torso
• Burns crossing joints (especially flexor surfaces)
• Deliberate abuse

ASSESSMENT OF THE BURNS PATIENT

• History of the patient, including any chronic conditions that may affect wound healing such as steroid use, diabetes etc. Check tetanus status.
• History of the events surrounding the injury, including:

• time of injury (fluid requirements assessed from this time)
• location of event (in open air, in closed room etc) to give an indication of concomitant injury including carbon monoxide or toxic fume inhalation, blast injury, trauma from fall etc.

• Full examination to exclude other injury.
• Assessment of the depth and extent of the burn injury using standard protocols such as Wallace’s Rule of Nines or the Lund and Browder chart (Figure 20.1).
image

Figure 20.1 Lund and Browder chart: estimation of extent of burn

ASSESSMENT OF DEPTH AND EXTENT OF BURN

Extent of burn

There are two methods of assessment of the extent of burns:

1. Wallace’s Rule of Nines chart—varies with age, good for quick assessment
2. Lund and Browder chart—allows for age variation, more accurate.

Depth of burn

The utilisation of terms such as first-, second- and third-degree has been largely replaced by:

• Superficial. Refers to epidermal reddening, e.g. sunburn. Extremely painful, no blistering, skin is red and heals spontaneously without scarring, usually within a week.

Note: Superficial burns are not counted in assessing the extent of burn injury.

• Partial thickness. Subdivided into superficial and deep:

• Superficial partial thickness—red or pink with mild blistering as involves dermis. Extremely painful but heals spontaneously within 1–2 weeks.
• Deep partial thickness—may be initially red then white. Harder to assess. Involves deep layers of dermis and is extremely painful. May require skin grafting to prevent infection and scarring.

• Full thickness. Involves all layers of skin including blood vessels, nerve endings, hair follicles and the dermis. As a result, they are insensate, dry, white, translucent or even charred. All but the smallest (< 1 cm) will require skin grafting.

GENERAL MANAGEMENT

• Remove the victim from the source of injury.
• Provide supplemental oxygen if there is any possibility of blast injury, smoke or toxic fume inhalations, stridor, hoarseness of the voice, burns to the face or any evidence of soot around the mouth or nose.
• Any burned patient removed from an enclosed space may be assumed to have airway injuries even when no burns are evident.
• Adherent material should not be removed at this stage.
• Antibiotics are not required prophylactically—only if specific infection demonstrated.

Analgesia

Superficial and partial thickness burns are extremely painful.

In minor or localised burns, application of cold water (for at least 30 minutes) and dressings alleviate pain.

Simple oral analgesia may be required at home.

Inability to control pain is an indication for admission, particularly in children.

In more severe cases, initial management includes narcotic analgesia. Narcotics should be given intravenously and liberally, e.g. morphine 0.1 mg/kg initially, then titrated to response. Large doses are often required.

Other factors

Airway/lung injury/inhalation injury

This may be caused by carbon monoxide or toxic fumes such as cyanide. Supplemental oxygen is required for all but minor burns and in all patients in whom there is actual or suspected inhalation injury (include patients with no evidence of burn but where there has been a fire in an enclosed space). Intubation may be required early in patients with cyanosis, respiratory distress, stridor or hoarseness. Anticipate lung injury or swelling of the airway if facial burns are evident.

Circulation

Where possible, IV lines should be inserted through unburned skin. Fluid requirements may be high in extensive burns at 2–4 mL/kg/% burn in the first 24 hours. Compartment syndrome or restriction of chest movement due to circumferential burns may require escharotomy as an emergency procedure.

Gastrointestinal tract

Gastric stasis or ileus can be assumed in all cases of > 20% burns. Except in minor burns, all patients should be nil orally until assessed regarding the need for urgent surgery.

Tetanus status

The usual protocols apply.

FLUID REQUIREMENTS

Significant fluid resuscitation after burns is required to maintain circulating volume and an adequate urine output. Volume losses can be anticipated and calculated from:

• patient weight
• extent of burn (body surface area—BSA)
• time from original burn injury.

There are a number of formulae available. The recommended fluid replacement and maintenance from the NSW Health burns transfer document are reproduced in Box 20.1.

Box 20.1 Recommended fluid replacement and maintenance in burns patients

Replacement

• In the first 24 hours after burn injury, 2–4 mL x kg x % burn BSA Hartmann’s solution.
• Give half of this amount in the first 8 hours and remainder over 16 hours.

Maintenance

• Adult: replacement plus 2–3 litres daily maintenance fluid. Add potassium as required in maintenance for losses due to muscle/skin damage.
• Child < 30 kg: 4% dextrose + N/5 saline or 3.75% dextrose + N/4 saline according to weight

Urine output

• Adult: aim for 0.5–2 mL/kg/h
• Child: aim for 1 mL/kg/h if < 30 kg

NSW Severe Burn Injury Service. Burn transfer guidelines. NSW Department of Health; revised August 2004

ADMISSION AND TRANSFER TO SPECIALISED BURNS UNIT

Nowadays, patients aged 15–44 years have at least a 50% chance of surviving a 70% total body surface area burn if treated in a specialist unit.

Referral criteria to specialised burns unit

• Deep burns involving 10% or more of body surface area (BSA) in adults or 5% BSA or more in children
• Burns involving the face, hands, feet, perineum, flexor joint surfaces
• Any inhalation injury
• Burns with associated injury, major preexisting disease or suspected child abuse
• Significant chemical or electrical burns

Admission criteria to general or plastic surgery unit

• Uncontrolled pain, particularly in small children
• Burns greater than 1–2% BSA full thickness or 15% BSA (adult) or 10% BSA (children) partial thickness

SPECIFIC BURNS

Thermal burns

Application of cool water (not ice) to minor burns for a minimum of 30 minutes may alleviate pain and reduce the severity of the injury. This is of no value if applied more than 3 hours after the injury.

If burns are extensive, there is a risk of hypothermia. Unburned areas should be kept warm with thermal blankets where possible.

Scalds are common in children—clothing soaked in hot liquid will cause further damage unless removed or cooled immediately. Adherent material should not be removed at home. Simple oral analgesia may be all that is required if small areas are involved.

Note: Accidental scalds usually have a scatter pattern with areas of unburned skin in between. A clear demarcation line may indicate deliberate abuse in children and in the aged.

Chemical burns

Copious amounts of water for at least 20–30 minutes are required to effectively dilute chemicals in the first instance.

There is a risk of further injury from the dilute chemical run off. Showers and removal of contaminated clothing may have occurred in the workplace.

Specific antidotes, if available, can be used after this initial treatment (see below, hydrofluoric acid).

The severity of chemical injury is related to a number of factors:

• pH of the agent
• concentration of the agent—some concentrated chemicals may produce heat when diluted, leading to thermal as well as chemical injury
• length of contact time
• volume of the agent
• physical form of the agent.

Acids generally produce coagulation necrosis by denaturing protein. This leads to the formation of eschar which tends to prevent further penetration of the acid. Alkalis act both by denaturing protein and by fat saponification (liquefaction necrosis). As a result, there is no barrier to further penetration and the damage may be more severe.

Hydrofluoric acid (HF) is one of the strongest inorganic acids. Used mainly in industry (e.g. car detailing, glass etching), the commonest exposure is to the hands and fingers. HF penetrates deeply before dissociating to free hydrogen and fluoride ions. The hydrogen ions are corrosive. The fluoride ions (tissue chemical burn) combine with calcium and magnesium to form both insoluble and soluble salts. Systemic fluoride ion poisoning from severe HF burns can lead to hypocalcaemia, hypomagnesaemia, hyperkalaemia and sudden death. Symptoms of tissue destruction and necrosis may be delayed. Initial treatment utilises topical calcium gluconate gel. In severe cases, calcium gluconate may need to be injected subcutaneously or intravenously.

Electrical burns: lightning, high voltage and domestic

Refer to Chapter 31, ‘Electrical injuries’.

PREVENTION OF INFECTION

Dressings

Necrotic tissue should be removed and the skin cleaned with a non-alcohol based cleanser prior to the application of dressings.

Dressings alleviate pain of irritated nerve endings by reducing exposure to air and clothing, resulting in a reduction in exposure to moisture and the risk of infection.

In small, superficial partial thickness burns

For small, superficial partial thickness burns, a variety of dressings have been suggested, including transparent dressings and Fixomul®, which do not require a daily change. Other closed ‘burns’ dressings, such as Vaseline® gauze or other dressings, require daily changes.

Silver sulfadiazine (SSD) cream is generally not recommended for outpatient care as it may become a potential source of infection after 24–48 hours. Acticoat® is another silver-based product that has replaced SSD in many Australian burns units, but requires specialist application.

In deep partial thickness and full thickness burns

For deep partial thickness and full thickness burns, excision followed by split skin or full thickness grafting may be required, unless skin substitutes are available.

Skin substitutes—characteristically the ideals are:

• Is readily available.
• Acts as a barrier to moisture and microorganisms.
• Is robust, elastic and non-antigenic.
• Adheres or integrates to the wound and minimises inflammation to promote healing.
• Currently available: biological skin replacements (allografts and xenografts) and bioengineered skin substitutes (autologous cultured and non-cultured skin products and biosynthetic skin substitutes).
• CellSpray® involves spraying on a suspension of cells cultured from the patient’s skin. The live skin cells rapidly proliferate to cover the burned area, and the risk of infection or scarring is reduced. Rejection is minimised as the cells are generated from the patient.1

SPECIFIC OTHER FACTORS

Circumferential burns. Circulation may be distally compromised in peripheries due to eschar. Reduced chest wall movement with hypoventilation is possible with circumferential burns to chest. Escharotomy may be required.

Note: Eschar is a result of full thickness burn and is, therefore, insensate.

Flexor surfaces of joints. Early prevention of contractures required. Compression garments may be applied in a burns unit.

Hands/feet/perineum. These are specialised skin areas with a high risk of circulatory compromise leading to the development of scars and subsequent deformity.

Child/aged abuse. Any suspicious burns, especially those with unusual appearance or in unusual places. The commonest burn injury in children is scalding.

Eyes. The eye is more resistant to acid than alkali. Copious washout, including eversion of the eyelids, is required to dilute the chemical prior to any specific antidote. Any solid particles must be removed from under the eyelids (especially powdered alkali) as this may lead to corneal scarring and opacification. pH should be checked to indicate washout is adequate. Molten metal should be left to cool before removal by an ophthalmologist.

Flash burns. From arc welding are acute corneal burns that generally heal without sequelae within 24 hours. The onset of symptoms is delayed for several hours and they are extremely painful. Topical local anaesthetic may be required initially to examine the eye but should not be used as treatment. Most do not require antibiotic treatment but pilocarpine drops can reduce pain, as can reduction of eye movement by application of eye pads.

Note: Be on the lookout for metallic foreign body overlooked on examination. Try not to pad both eyes if possible. Local anaesthetic puts patient at risk of being unaware of further foreign body. Sunglasses can help.

Extremes of age. In general, the larger the burn and the older the patient, the lower the chance of survival. A child has a relatively larger surface area in the most common burns, such as scalds around the head and face, increasing the risk of complications.

Airway/lung injury. If not immediately evident, blast injury, carbon monoxide or other toxic chemical inhalation and burns to the upper airway are potentially fatal injuries if overlooked and untreated. A chest X-ray is required in any patient in whom airway injury is suspected.

Any other concerns can always be discussed with local burns unit medical staff.

Note: Burns must be regularly reassessed as wound management varies according to the depth of the burn. This is often hard to accurately determine on presentation and is often initially underestimated. It becomes more obvious with time.

REFERENCES

1 Wood F., Stoner M. Spray on relief for burns. Australian Academy of Technological Sciences and Engineering Focus No. 137. May/June 2005.

RECOMMENDED READING

Glattner R. Highlights of the 12th Annual Scientific Assembly of the American Academy of Emergency Medicine. San Antonio, Texas, Feb 2006. Online. Available: http://www.medscape.com/viewarticle/528296_1.

NSW Severe Burn Injury Service. Burn transfer guidelines. NSW Department of Health;. August 2004. revised

Papini R. ABC of burns: management of burn injuries of various depths. BMJ. 2004;329:158-160.

Shukla P. Initial evaluation and management of the burn patient. emedicine. Feb 2008.

Singer A.J., Brebbia J., Soroff H.H. Management of local burn wounds in the ED. Am J Emerg Med. 2007;25(6):661-671.

Wood F., Stoner M. Spray on relief for burns. ATSE Focus. 137, May/June 2005.

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