Skin Substitutes in Burn Care
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Large surface area burns continue to be one of the most difficult and deadly problems the medical community faces today. Although major strides have been made in burn care throughout the years, many difficulties remain. Historically, some rather bizarre and egregious concoctions, at least by modern standards, have been applied to burns to promote healing. Barbara Ravage, author of Burn Unit, records and describes fascinating unguents and emollients that include using calf dung and black mud as topical burn treatments, as recorded in the Ebers Papyrus from the 1500s BC.1
While partial-thickness burns have the ability to heal on their own while restoring relatively normal skin architecture, full-thickness burns do not. Full-thickness burn injuries that destroy both the epidermis and dermis produce irretrievable skin loss, since completely destroyed dermis does not regenerate. Although a full-thickness burn wound may heal with a contracting scar tissue base and an overgrowth of thin epidermis, it lacks many of the normal structures and basic functions of skin. Temperature regulation, sensory perception, excretory function (through sweating), and metabolic activities such as the formation of Vitamin D, to mention but a few, are either severely compromised or completely lost.2 Some skin barrier function may be maintained; however, the resilience and elasticity of normal skin are never recovered. Thick, even hypertrophied scarring is often the hallmark of burn healing.
Although partial-thickness burns may heal spontaneously, skin grafting provides the best results for deep partial- to full-thickness burns. Most burn surgeons would agree that the best replacement for a full-thickness burn is a full-thickness skin graft. Unfortunately, the amount of full-thickness skin that can be donated willingly from other parts of the body for transplantation is limited, and the old principle of “robbing Peter to pay Paul” rapidly comes into play. Therefore, large burns requiring excision are treated with split-thickness grafts of varying thickness. Split-thickness donor sites heal and can be re-harvested. This allows for multiple cropping from the same site, although the process is not without limits.
While split-thickness skin grafts are satisfactory they are not perfect, as only a small portion of dermis is transplanted with each split-thickness graft. The ideal skin replacement product is one that is readily available off the shelf, is dependable, easy to use, infection resistant, has a low profile of side effects, demonstrates an acceptable appearance, is reasonably priced, and restores both the dermal and epidermal layers of the skin to its original state. While this chimerical creature does not exist, strides have been made in reaching that goal and the search is ongoing.
Skin substitutes are often categorized as either temporary or permanent and are also thought of as products that provide temporary wound coverage or wound closure.3,4 In actuality, few (if any) of the products used to treat burns today are permanent skin substitutes. Deciding whether a product is a temporary or permanent covering and whether or not it produces formal wound closure as opposed to simple coverage is somewhat arbitrary and can be confusing.5
1. Ravage B. Burn Unit: Saving Lives After the Flames. Cambridge, MA; Da Capo Press: 2004.
2. Chuong CM, Nickoloff BJ, Elias PM, et al. What is the ‘true function’ of skin? Exp Dermatol. 2002;11(2):159–187.
3. Burnsurgery.org. Education Module II:
The Burn Wound. Available at: http://burnsurgery.org/Modules/BurnWound/index.htm. Accessed: May 2008.
4. Jones I, Currie L, Martin R. A guide to biological skin substitutes. Br J Plast Surg. 2002;55(3):185–193.
5. Hansbrough JF, Franco ES. Skin replacements. Clin Plast Surg. 1998;25(3):407–423.
6. Eisenbud D, Huang NF, Luke S, Silberklang M. Skin substitutes and wound healing: current status and challenges. WOUNDS. 2004;16(1):2–17.
7. Burke JF, Yannas IV, Quinby WC Jr, Bondoc CC, Jung WK. Successful use of a physiologically acceptable artificial skin in the treatment of extensive burn injury. Ann Surg. 1981;194(4):413–428.
8. Rheinwald JG, Green H. Serial cultivation of strains of human epidermal keratinocytes: the formation of keratinizing colonies from single cells. Cell. 1975;6(3):331–343.
9. Biobrane product information. Available at: http://wound.smith-nephew.com/uk/node.asp?NodeId=3562. Accessed: May 2008.