Burns

Published on 23/06/2015 by admin

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3.5 Burns

Peter Barnett

Essentials

1 Burns are one of the leading causes of injury in children in Australia.
2 The definitive assessment of the ‘depth’ of the burn may be difficult early on, as the appearance can evolve during the first 24–48 hours.
3 The calculated amount of fluid (burn-deficient plus maintenance) to be replaced in 24 hours is only a guide and should be adjusted according to the child’s haemodynamic response.
4 Children with major or complicated burns should be treated in a paediatric burns unit.
5 Consider non-accidental injury if the presentation is delayed or if the history given is inconsistent with the burn sustained.
6 Electrical injuries are more commonly seen in two age groups: toddlers within the home setting and male adolescents involved in risk-taking behaviour. High-voltage exposures have a more serious outcome, as they are more likely to be associated with injury to internal structures.

Introduction

Burns sustained by children are a common presentation to emergency departments and often cause significant distress to both the child and the parents. The mortality is increased in younger children. Deaths are generally related to flame burns, which may be complicated by inhalation of smoke and other toxic gases (e.g. in house fires). Early fatalities are related to respiratory complications, whereas late deaths are usually related to infection. The use of early debridement and skin grafting has led to an increased survival rate in patients who would have previously died because of infection.

Most burns are fortunately less serious, resulting mainly from scalds. This commonly occurs in pre–school-aged children due to their inquisitive nature precipitating accidents in the home. Flame burns occur in older children often experimenting with inflammables. Chemical and electrical burns are uncommon. One must be alert to the possibility of burns presenting as a manifestation of non-accidental injury in a young child.

Several preventive strategies can help decrease the risk and degree of burns sustained, especially with thermal burns. Lowering the temperature of hot water heaters to a maximum of 50°C significantly increases the contact time needed to produce deep or full-thickness burns. Flame-resistant clothing and smoke detectors in homes have saved many lives. Spill-proof mugs, guards around wood fire stoves, and child-resistant taps have all been shown to prevent burns. Further prevention strategies will have a far bigger impact on burns than advances in burn management.

Pathophysiology

The skin is the largest organ in the body, and its functions include:

• preventing heat loss to the environment, thus regulating the body’s temperature;
• preserving body fluids by preventing water loss from the body;
• acting as a barrier to infective organisms.

Therefore children with extensive burns have difficulty retaining fluid and regulating temperature, and are at risk of infection.

The skin is composed of two main layers.

Epidermis: composed of stratified squamous epithelium, which is largely non-viable. It acts as the barrier to infectious agents as well as preventing fluid loss from the body.
Dermis: contains the epithelial adnexal structures, e.g. hair follicles, sweat glands, and neural receptors for pain and pressure. It also contains blood vessels, which contribute to temperature regulation of the body via radiant heat loss.

After a burn, injury to the deeper specialised epithelial cells prompts a change into stratified squamous epithelium. These cells proliferate, gradually covering the burn with a non-epithelial barrier. Therefore, if the dermal structures are damaged, skin grafting is the only means to cover the skin. When these deeper layers are involved, scarring results and contractures may occur.

The depth of the burn will depend on the temperature of the substance in contact with the skin, the length of time the substance is in contact with the skin, and the extent of subsequent cooling of the burned skin area. Hypothermia due to cooling occurs quickly in children due to their higher surface area to weight ratio, compared to adults. Also, children have thinner skin, which leads to deeper burns for a given contact temperature and duration.

Classification

Burns are generally classified into superficial, partial thickness or full thickness. Previous nomenclature (first, second, and third degree) has been replaced to give a more accurate description of the burn. In the emergency department setting, the definitive assessment of the ‘depth’ of the burn may be difficult, as the appearance can evolve during the first 24–48 hours. Likewise, the burn is not generally uniform in depth, and it may take time to delineate between superficial and deeper areas. Superficial and partial-thickness burns are the most common burns seen in children.

Superficial

Superficial burns generally involve only the epidermal layer. These are commonly seen resulting from sunburn or minor scalds. Blistering does not occur immediately but may over the next few days. The pain and swelling generally last only a few days. The skin is erythematous and blanches normally. The epidermis will often peel within 3–7 days and is completely healed by 7–10 days, without scarring.

Partial thickness

Partial-thickness burns occur when the whole epidermis is involved and part of the dermis. The more of the dermis that is involved, the increased scarring potential.

Superficial

partial-thickness burns involve the papillary layer of the dermis and are characterised by erythema with blistering. The blisters may remain intact and later burst due to an external pressure. The skin underlying the blister has a pink or red colour and moist appearance. These burns are extremely painful, as the nerve endings are exposed. The deeper the burn, the slower the healing process. Generally, superficial partial-thickness burns heal in 2–3 weeks.

Deep

partial-thickness burns involve the reticular layer of the dermis. They may be less painful than their more superficial counterpart, due to oedema lessening the exposure of the nerve endings. They are a paler colour with a speckled appearance due to thrombosed superficial vessels. The skin is non-blanching. It may initially be difficult to distinguish between full- and deep partial-thickness burns. Deep partial-thickness burns generally heal after 3–6 weeks. Scarring is common, and skin grafting is sometimes necessary.

Full thickness

Full-thickness burns generally occur after flame burns or after prolonged contact with a hot surface. Other causes include hot oil, prolonged immersion, or chemical burns. They involve the epidermis and all the dermis, including epidermal appendages. They have either a dry, hard, white, leathery appearance or may be black in colour. They usually have no sensation because the nerve endings have been destroyed, and pain is due to more superficial burns on the edge of the full-thickness burn. Full-thickness burns are able to heal only from skin regrowth from the edge of the burn, which causes scarring. Therefore most will require skin grafting.

All significant burns will become colonised with bacteria. Heat causes coagulation of tissue, which leads to oedema and non-viable skin. This will potentially become a rich source of nourishment for bacteria. Adequate debridement is required to reduce the risk of infection. Infection will increase the depth of skin damage and thus the degree of scarring.

The location of the burn is also important regarding potential scarring, contracture, and caring for the acute burn. Facial, hand, foot, and perineal burns may be difficult to dress. Hence the part of the body involved by the burn will influence whether inpatient or specialist care is required.

History

The history is generally obtained from the parent to clarify events. Ambulance officers may have important additional information. It is important to know the substance and estimated temperature of the substance that caused the burn (e.g. hot cup of tea, cooking oil, flame), and the duration of contact with skin (e.g. was the patient clothed at the time, in what, and for how long?).

With flame burns, was the patient trapped in an enclosed space, therefore at risk of inhalation problems, or was there any loss of consciousness? These features may suggest inhalation issues such as carbon monoxide poisoning. The historical information may determine the potential for associated injuries resulting from falls or explosions.

Non-accidental injury should be considered if the presentation is delayed or where the history given is inconsistent with the burn sustained or if the burn has distinctive distribution (e.g. glove and stocking). Past medical history and immunisation status, particularly for tetanus, should also be obtained (see Chapter 1.1).

Examination

Note that children who are distressed may require the provision of immediate appropriate analgesia at the outset to aid examination.

Primary survey

The initial assessment of the child should be directed to the presence of any features that suggest potential airway involvement. These include singed nasal hairs or eyebrow hairs, oral or facial burns, coughing up carbonaceous sputum, barking cough, altered voice, stridor, wheeze, or respiratory distress. Airway compromise (upper or lower) may have an insidious onset, so frequent re-examination of the child is vital during the first 12–24 hours. If stridor or hoarse voice is present, this indicates upper airway involvement, and early intubation is required prior to evolving oedema causing total airway obstruction. Delayed intubation in this setting can be increasingly hazardous due to distortion of the normal laryngeal anatomy. Scalds to the face rarely cause airway compromise, unless the child has ingested hot liquids.

The circulation status should be assessed next. Hypovolaemia resulting from third-space fluid loss will not occur for a few hours after a severe burn. Therefore, if early-onset cardiovascular instability is present, then an alternative explanation, such as bleeding, should be sought. The peripheral perfusion of limbs should be assessed where circumferential burns are apparent. Comparing the pulse wave forms of various digits on the limb using a saturation oximeter may assist this in questionable instances.

Evaluation of burn area

The extent and depth of the burn should be assessed after the patient has been stabilised. This is usually done from a body chart (Fig. 3.5.1

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