Real Numbers
1.5 Decimal representation of the reals Note: 1 lecture (optional)
much more in use currently. These dressings, though effective, are very expensive.
Timely and effective use of these topical antimicrobial agents have revolutionalised burn care by decreasing invasive wound infections that may progress to septicaemia and death.31 The topical agents have become very popular and very effective. However, one of the most tasking aspects of burn care is the wound dressing which – depending on the size of the wound – can be very demanding on the patient and care providers. It contributes heavily to the cost of burn care. For instance, a pack of six 40x40cm sheets of Acticoat dressing costs about a quarter of a million Naira!67 This Acticoat pack can be used up in a single dressing session for a patient with burn injuries of about 50% TBSA. The longer dressings have to go on, the greater the cost of treatment. The equipment used for dressing burn patients, such as shower trolleys and dermal jets, also is not cheap.
Biologic dressings can also be used. These include skin grafts which may be autologous, homologous (usually cadaveric), or heterologous (such as porcine skin). Some workers have used vegetable materials such as potato peels.68
The introduction of total excision and grafting of the burn wound has decreased wound complications, sepsis, and length of hospital stay.69 Cope and others introduced the idea in 1947,70 and it has been the subject of much research and interest since the classic paper by Janzekovic in 1970.71 This practice has had profound effects on burn wound mortality and is the treatment of choice for full thickness burn wounds in centres with the expertise and resources for it. It aims at removing devitalized tissue and restoring skin continuity. A positive nitrogen balance is maintained, and weight loss reduced.
Although many studies have disputed any advantage over the serial method,72 massive early wound excision and grafting sometimes done within 24 hours of injury seems to be the preferred method.30,46,73,74 Some studies have found blood loss to be less when wound excision is done within 24 hours of injury.75
The practice of leaving full thickness burn wounds to separate on their own only serves as a nidus for inflammation and infection that could lead to the patient’s death.46 This conservative practice is now reserved for the elderly and in the few cases where surgery and anaesthesia are contra-indicated.46 Indeed, patients with deep partial thickness burns over 40%
TBSA who have significant co-morbidities should be considered for early excision and grafting.46
A major limitation is the availability of donor skin. The optimal donor site should be a hidden, broad, convex surface such as the buttocks, upper thighs, lower trunk, and the scalp. For burn patients, the choice of donor sites may be limited. The aim will be to find sites where split thickness skin grafts can be readily harvested, followed by rapid healing of the donor site to allow re-cropping of skin if necessary. The skin may be meshed.
For patients with burn wounds less than 20% TBSA, the wounds can be excised and grafted in one session. Massive burn wound (>60% TBSA) excision may also be done in a single session. However, staging may be done to enhance donor site cosmesis, as donor site morbidity may worsen the outcome. Staging allows repeated use of the same donor site.30
In major burn injuries where mortality is a serious concern, the availability of cadaver allograft skin has altered the treatment.46 A typical method of treatment is to use widely expanded autografts (1:4 or more) covered with cadaver allograft to completely close the wounds for which autograft is available.30,73 Within 21 days, the widely meshed skin usually heals beneath the cadaver autograft, which sloughs off gradually as it is rejected. Parts of the wound for which autograft are not available are covered with allograft skin pending when autograft is available. Ideally, areas of less cosmetic importance are covered with meshed graft first, and
areas such as the face and hand, with sheet grafts later.30 Sheet grafts are also used over joints.
Priority is given to the need to reduce the overall necrotic load. Thus the order of excision is broad areas such as the trunk and lower limbs first.46 The early excision and grafting of deep burn wounds of the hand give excellent functional results.76,77
Most burn surgeons excise the burn wound in the first week. Some will excise 20% per session on subsequent days. Others remove the entire wound in one operative session.73 Massive blood loss and hypothermia are limiting factors to massive early burn wound excision.74,75 A variable high-pressure water jet – Versajet - is a promising tool particularly for partial thickness burns in both paediatric and adult patients.78,79 It is said to preferentially excise burnt skin, but is quite expensive.
While performing the surgery for total excision and grafting, the surgeon must ensure that there is a viable bed and no accumulation of fluid between the graft and the wound bed. He must also ensure that there are no shear stresses on the wound, and avoidance of massive micro- organism proliferation.46