VOL: 97, ISSUE: 48, PAGE NO: 53
Christine Dearden is A&E consultant
Janice Donnell, RGN, RSCN, is a staff nurse, Eithne Tieney, RGN, is sister, regional burns unit, Royal Hospitals and Dental Hospital Health and Social Services Trust, Belfast, Northern Ireland
The initial care of a patient with a wound is always directed at the preservation of life over limb. This article will focus specifically on the management of superficial and partial thickness burn injuries. The management of complex, extensive or full thickness wounds will not be discussed, as these require intensive resuscitation and specialist management, preferably in a burn centre.
The burn injury
At a cellular level, three zones of tissue change may be noted:
- The zone of coagulation - the centre of the burn contains coagulated blood vessels. If this zone is within or deeper than the dermal layer the tissue will die and slough off. If it is above the dermal layer, spontaneous healing will occur through re-epithelialisation (Jordan and Harrington, 1997);
- The zone of stasis - this surrounds the burn centre. Although blood supply is sluggish, due to aggregation of white blood cells, this tissue has the potential to recover (Trofino, 1991);
- The zone of hyperaemia - this is the outermost zone and is essentially the burn border. This becomes red due to the inflammatory process. The tissue in this zone should recover completely; Damaged capillaries become more permeable and leak large amounts of plasma into the tissues. The accumulation of this fluid may cause the epidermis to separate from the dermis, resulting in blister formation. The build-up of blister fluid may cause local pressure necrosis (Flanagan and Graham, 2001).
- Practice point
Due to the damage to the micro-circulation, burn wounds are at an increased risk of infection and delayed wound-healing.
Superficial burn wounds
A superficial burn wound - for example, sunburn - only affects the epidermis. It will initially appear pink or red in colour. The area of hyperaemia will blanch when pressure is applied and capillary refill is quick following release. There may be slight swelling and the skin may blister after an interval of 12-24 hours.
Superficial burn wounds usually heal without scarring in three to seven days because there is still a sufficient number of surviving epithelial cells available to allow the wound to achieve rapid epithelialisation. A superficial burn wound is extremely painful due to damaged nerve endings.
Superficial partial thickness burn wounds
Superficial partial thickness burn wounds involve the epidermis and the upper layer of the dermis. Large blisters develop and there is skin loss. The burnt area swells and will appear moist and bright pink or red in colour. The hyperaemic area will blanch with pressure and, again, capillary refill is brisk. Pain in response to a pinprick with a sterile needle confirms the presence of viable dermal cells.
Healing can take up to three weeks and some scarring may result. Some partial thickness wounds require skin-grafting, particularly when function is at risk due to the risk of contractures.
- Practice point
Some epidermal cells lining the hair follicles and sweat glands may survive; these will regenerate and speed the epithelialisation process.
Deep dermal burn wounds
Deep dermal burn injuries destroy the epidermis and almost all of the dermis. The burnt area appears mottled red and white. The area may not blanch due to the extravasation of blood from damaged dermal capillaries; at best, capillary return is sluggish. The presence or absence of pain will depend on the amount of damage sustained by pain receptors - for example, if pain receptors have been destroyed the wound will be insensate.
Wound-healing may take more than three weeks and the end result may be poor. For example, there may be poor quality skin cover involving keloid scarring. In view of this, the patient should be referred to a surgeon with a special interest in burns and plastics regarding excision and grafting (Parker and Copley, 1993).
Full-thickness burn wounds
Full-thickness burn wounds destroy the epidermis and all of the dermis. They may also include destruction to adipose tissue, muscle, tendon and bone. The wound bed may appear dry and leathery. The colour of the wound may vary from pearly white to cherry red, brown, tan and black. Thrombosed veins may be visible and the wound bed will be insensate.
By the time the patient reaches A&E it may be too late to implement first aid measures, as most of the heat will have dissipated from the burn. However, it is imperative that practitioners are aware of good practice, as they may be called on to administer first aid outside an acute setting.
For burns caused by wet heat, such as boiling water, steam or bitumen and for those caused by dry heat, such as flames or contact with a hot object, immerse the burnt area under cold running water for at least 10 minutes. This will help to dissipate heat away from body tissues (Lawrence, 1997). Cold running water is recommended, as the burn injury will heat up still water.
Do not immerse the area in cold water for longer than 20 minutes, as this can lead to hypothermia. Remove rings, watches and restrictive clothing before the area begins to swell. Adherent substances, such as bitumen, should not be removed, as these may pull off the underlying skin.
- Practice point
Do not wet cement or lime, as these substances only cause burns when wet - brush off dry powder from the skin before flushing the injury with water (Lawrence, 1997). Remember that burns caused by flames may have an inhalation component.
In February 2001 the British Burn Association published guidance on the type of injuries that should be transferred for specialist management (Table 1).Most small superficial and partial thickness wounds can be managed in a minor injury or A&E setting. It is important to note that small equates to less than 5% total body surface area in paediatrics and to less than 10% total body surface area in adults.
Extensive, circumferential or full thickness burns plus partial thickness burns involving the eyes, face, hands, joints or genitalia must be referred to specialist burn centres (Gower and Lawrence, 1995). This is because of the potential for functional impairment, cosmetic disfigurement and mortality; for example, burns to the face can result in airway obstruction. A recalcitrant superficial burn may also need to be referred, as a skin graft may be necessary to aid or complete healing.
Estimating wound size
The ‘rule of nine’ is easily memorised and can be used by all practitioners to make a quick estimation of burn size (Fig 1). It can also be adapted for use in children. Remember that the palmar surface of the patient’s hand (with fingers closed) is equal to approximately 1% of the patient’s body surface. This is useful for measuring the surface area of small burns.
A more accurate measure of a surface area of a burn may be determined using the Lund and Browder chart (Settle, 1986).
- Practice point
Silver sulphadiazine should not be applied before transfer to a specialist unit, as it discolours the wound, making assessment difficult. The patient may also experience additional pain as the silver sulphadiazine is removed for assessment. The risk of airway obstruction means that burns to the face cannot be occluded. Simply cover with a specialist non-adherent burn dressing or saline soaks during transfer. For other areas of the body cling-film is a useful temporary dressing. This must be applied loosely in order to prevent a tourniquet effect. If the individual’s hands are affected they should be elevated to reduce oedema.
Wound care goals
The aim of treatment is to remove non-viable tissue, control colonisation, manage exudate and achieve coverage of the wound as quickly as possible (Bayley, 1990; Greenfield and Jordan, 1996).
Owing to the high risk of infection an aseptic dressing technique is essential. Attention to good hand-washing techniques as well as gloves and aprons play an important role in this process. The burnt area should be irrigated with normal saline. A non-perfumed soapy solution may be required in order to remove firmly adherent soot and dirt from the wound. Loose devitalised epithelium needs to be trimmed back with sterile scissors, and remnants of burnt clothing should be gently removed.
Practitioners should expect a high amount of serous discharge, particularly over the first 24-48 hours. This is because capillaries in the affected tissue become widely dilated and increase in permeability, allowing albumin, electrolytes and water to pass into the extravascular tissues.
The wound should be reassessed at least once within the next 48 hours because damage to the microcirculation is at its greatest in the first 12-24 hours following injury, due to the release of vasoconstrictive cytokines (Flanagan and Graham, 2001). It is therefore essential to check that the burn is not more extensive than first thought.
Partial thickness wounds should be closely monitored for at least two weeks, as it may take some time for the depth of the burn and the potential outcome to be fully realised.
If the burn has not healed within two to three weeks the patient should be referred to a burns unit for specialist management. Once the wound appears to be healthy, the dressing should be disturbed as little as possible in order to promote granulation and epithelialisation.
The ideal burn dressing should:
- Control colonisation;
- Promote rapid granulation and epithelialisation;
- Be non-adherent in order to minimise pain and prevent damage to granulating tissue and regenerating epithelium at dressing changes;
- Manage exudate;
- Not hinder movement or compliance with physiotherapy;
- Not compromise the circulation.
A large variety of ‘modern’ wound dressings meet these criteria - traditional tulle gras and gamgee-type dressings do not. This is because the former allows granulating tissue to grow through and become entwined within its mesh, and the latter allows rapid strike-through of exudate. An alternative to tulle gras is a non-adherent silicone dressing such as NA Ultra or Mepitel. In the acute phase a highly absorbent secondary pad will be required. As swelling is an expected feature of burn wounds, the dressings should be applied loosely in order to prevent it acting as a tourniquet.
Once the acute phase is over and the exudate level has reduced, the wound may be protected with any number of dressings - for example, a non-adherent dressing, a semi-permeable film dressing or a hydrocolloid.
Due to the functional importance of the hand and the high risk of contractures associated with burns, it is essential that the hand and fingers are mobilised throughout the treatment period. In minor injuries each finger should be dressed individually without restricting movement. Hand exercises should be encouraged. In larger superficial burns to the hand - for example, scalds - the entire hand may be placed in a polythene bag for 24-48 hours. Placing liquid paraffin or an antibacterial cream such as silver sulphadiazine inside the bag may help to soothe the burn and prevent it sticking to the wound. However, as polythene bags are not permeable moisture will accumulate and there is a risk of skin maceration.
Silver sulphadiazine cream
At one time, silver sulphadiazine cream was seen as the ‘gold standard’ burn dressing. Now its use is being questioned as it discolours the wound (making assessment difficult), macerates healthy tissue and may cause kernicterus. Also, as silver may be absorbed into the body through an open burn it may have a cytotoxic effect on neutrophils and lymphocytes and contribute to local immune dysfunction (Zapata-Sirvent and Hansborough, 1993). It is not recommended for use in children under three months or in pregnant women.
On the positive side, silver sulphadiazine may help to prevent infection by maintaining a low bacterial count on the wound bed (Greenfield and Jordan, 1996). It also appears to have a cooling and soothing effect. Silver sulphadiazine cream should only be applied if its benefits are thought to outweigh any harmful effects. In our area of practice silver sulphadiazine cream is used on minor burns for only a very short time (two to four days). After this the wound will be dressed with a non-adherent dressing designed to promote moist wound-healing.
Burn blister management is open to debate. This is because burn blister fluid can have beneficial and detrimental effects. Flanagan and Graham (2001) recently carried out an excellent review on this subject. Their main findings are summarised in Table 2.
There also appear to be two schools of thought on the de-roofing of blisters. Some practitioners believe that they should be completely de-roofed, as any remaining skin may be a potential source of infection. Others believe that, once the blister has burst, the sac should be retained and allowed to act as a biological dressing (Fowler, 1996).
Whichever tack is taken, it is important to remember that exposure of partially burst dermis can lead to rapid desiccation and conversion of a superficial burn to a deep burn (Zawacki, 1974). Therefore, after bursting or deroofing blisters it is crucial to cover the wound with a moist dressing.
Once healing has occurred the patient should be encourage to massage the area with a non-irritating mild lubricating cream to help restore normal texture and prevent dryness.
The disfiguring effects of even a small burn on patients, their partner and family should not be underestimated. The associated psychological distress can lead to feelings of depression and social isolation. Counselling interventions and support networks such as the charity Changing Faces may help the patient to adapt to the change in body image.