**2.2 Clinical applications of skin substitutes in acute burn care**

To appreciate the use of skin substitutes in acute burn care an understanding of the pathophysiology of burn injury is essential. A burn is a defined an injury to tissues induced by heat, cold, friction, chemical, radiation or electrical energy. With regards to the utilisation of dermal substitutes for cutaneous burn wounds, the three most important factors are depth, size and anatomical location of the cutaneous burn.

## *2.2.1 Burn depth*

Burn depth can be epidermal only, dermal (ranging from superficial to deep dermal) or full thickness. In real terms there are only two burn depths. In the first group the burns are superficial enough to heal spontaneously with acceptable functional and aesthetic outcome. These burns are classified as epidermal, superficial

#### *Role of Skin Substitutes in Burn Wound Reconstruction DOI: http://dx.doi.org/10.5772/intechopen.105179*

partial thickness and mid-dermal. The treatment is supportive and the corner stay is prevention of infection, which can deepen the burn and the control of pain. Pain control facilitates dressing changes and improves compliance with therapy and mobilisation. These burns heal spontaneously as there is an adequate volume of undamaged residual dermal tissue in the burn bed, as well as nests of epidermal cells located in the invaginated sheaths of adnexal structures. This results in re-epithelisation.

The second group (deep dermal to full thickness burns) undergo prolonged healing with granulation tissue and wound contracture, resulting in secondary intention healing. The treatment priorities for this group of burns is to abort the process of secondary intention healing replace it as closely as possible with primary intention healing. The surgical methods for doing this include excision and direct closure of small burns and burn wound excision with split thickness skin grafting for larger burns.

#### *2.2.2 Burn size*

As burn size increases the treatment options become more complex. Small burns of any depth can generally be managed with dressings or relatively minor procedures. For the more superficial burns increasing burns size results in increasing the frequency and volume of dressings, restricting mobility and more likely to cause pain. For deeper burns that require skin grafting the larger the burn the smaller the area of "donor" site for skin graft harvesting. The skin grafts are subsequently "meshed" to allow a greater surface area to be covered. The larger the size of the burn the smaller the donor site area becomes resulting in thinner grafts with wider mesh patterns and subsequent poorer scarring outcomes. Additionally, for burns of over 50% TBSA there may not be enough skin donor site to close the debrided burn wounds. Skin grafts can be harvested from the same donor site, but the area must be healed first, and temporising options are required to cover the debrided wounds.

#### *2.2.3 Anatomical locations*

Burns over joints can be challenging to manage. Superficial burns require early mobilisation to prevent stiffness and deeper burns require meticulous debridement and skin grafting and intensive mobilisation. Debrided full thickness burns may result in the exposure of deeper structures such as tendon and bone. This results in unfavourable reconstruction if skin graft is used alone and often skin graft failure.

#### *2.2.4 Skin substitutes replacing the epidermis: treatment of superficial dermal burns*

For superficial partial thickness burns where the epidermis and a variable amount of dermis is damaged skin substitutes designed to replace the epidermal layer are of value, particularly in larger burns and burns of the hands and joints. Examples of materials that are commonly used as epidermal substitutes in acute burns include:


To be of benefit epidermal substitutes must be applied shortly after the burn injury, preferably within 24–48 hours. The burn wound must be meticulously cleaned and residual debris including particulate matter and detached epidermis removed.

Shaving the skin is also recommended as is a through wash with iodine solution. Application under general anaesthetic or sedation is recommended as the preparation may be painful. Mobilisation can begin at 48 hours and once the substitute has adhered. Dressing changes will only require the outer layers to be removed at the substitute should remain intact and undisturbed. Within 2–3 weeks it is expected that the substitute will detach as the skin beneath re-epithelialises. It is imperative to monitor for infection and if this occurs the substitute must be removed and conventional dressings applied. The risk of infection can be reduced with meticulous burn wound preparation and consideration of antibiotics.

Epidermal substitutes play an important role in the management of burns that are destined to heal themselves by preventing infection (which may convert the burn into a deep dermal/full thickness injury that will not heal by itself) and treating pain (allowing patients to tolerate dressing changes, early mobilisation and expediting hospital discharge).
