Skin grafts are used in treating partial thickness and full thickness burns. Early surgical removal (excision or debridement) of burned skin followed by skin grafting reduces the number of days in the hospital and usually improves the function and appearance of the burned area, especially when the face, hands, or feet are involved. However, if the patient’s life is in danger skin grafting is usually postponed.
The best skin grafts come from the patient’s own unburned skin (donor sites). The grafts (called autografts) will ideally come from locations that are not ordinarily visible, such as the buttocks or upper thighs, because the donor sites will not be normal in appearance after they heal. However, the size of grafts that are needed and the location of burns will also determine where the grafts are taken from.
An instrument called a power dermatome is set to a particular depth and shaves off a uniform layer of healthy skin to graft onto a burned site. The thickness of the skin graft depends on the area needing the graft. Most grafts are “split” (partial) thickness. The donor site for a split thickness graft does not need to be surgically closed and will ordinarily form a new top layer of skin in 10 to 14 days. In many cases donor sites can be used again for additional grafts. Because skin around a split thickness graft usually contracts and grows tighter, full thickness skin grafts may be needed in areas such as around the eyes, where tight skin could prevent the eyelids from fully closing. A full thickness donor site needs to be surgically closed. For large areas requiring skin grafts, a “mesh” is made out of multiple skin grafts. The area to be grafted has the dead skin removed (debrided), often with a power dermatome, in preparation for the graft.
The patient’s donor sites can often be used more than once for grafts after a new layer of skin forms on the donor site, although there is a limit to how many grafts can be taken from the same site. Grafts from skin banks and other living and synthetic grafts are also available.
Skin banks are similar to blood banks. They test for communicable diseases and store skin from individuals who agreed to be organ donors before dying. The donor skin (called an allograft) is preserved in a solution or frozen. Grafts from skin banks are used as a temporary covering to protect against infection, reduce pain, reduce fluid loss, and allow the tissues underneath to heal. However, because the body’s immune system recognizes an allograft as being foreign, it rejects the graft in 1 to 3 weeks. It is then removed.
“Biotechnology” has recently produced new types of skin grafts. CEA (cultured epithelial autograft) uses living skin cells from the burn patient to grow new skin cells in sheets in a laboratory. Because the skin cells come from the patient, they are not rejected and form a permanent new skin layer. The sheets of CEA are very thin (10 – 15 cells thick) and fragile; they have the strength when first applied of wet tissue paper and are easily torn. In patients with massive burns, CEA produces a better cosmetic result than if it weren’t used, but CEA patients often require longer hospitalizations and more surgeries to release contractures because of the need to reduce movement to avoid damaging the delicate grafts until they are established. Products like Integra use products from animals, including collagen and condroitin, in combination with silicone to form a synthetic skin substitute as a temporary covering for massive burns.