Partial-thickness grafts consist of epithelium and part of the dermis. They're typically used on larger wounds that preclude the use of full-thickness grafts, such as traumatic wounds or burns, and are placed either as sheet grafts or meshed grafts. Sheet grafts are used in cosmetically or functionally important areas, such as the face, hands, feet, or perineum. Meshed grafts are typically used in areas that are less cosmetically and functionally important or when donor sites are limited (for example, in a patient with burns that cover 50% of his total body surface area).
In this article, we'll discuss the harvesting and placement of partial-thickness grafts, along with the care of meshed grafts.
Don't be partial
A partial-thickness graft can be harvested from virtually anywhere on the body, but the donor site is usually located in a cosmetically unimportant area with a large surface area, such as the thigh, back, or buttocks (see Common skin graft donor sites). A layer of dermis is left behind at the donor site, which typically repopulates the wound with epithelial cells in 5 to 10 days. For this reason, a partial-thickness graft can be used to cover a large surface area because the resulting donor site heals spontaneously.
A device called a dermatome is used to harvest partial-thickness sheet and meshed grafts. Using a razor blade that oscillates rapidly back and forth, the dermatome splits the skin horizontally into the skin graft and leaves a layer of dermis behind. It can be adjusted to harvest grafts of varying thickness. The harvested graft can then be placed as a sheet graft or go through the meshing process before being placed as a meshed graft.
Let's take a closer look at the meshing process.
Mesh it up
To create a meshed graft, a machine is used to put open spaces in the graft in an organized fashion. This expands the graft so it can cover a larger surface area. Partial-thickness grafts can be meshed in a variety of sizes, such as:
1:1 meshed graft-has open spaces that are equal to the size of the skin
2:1 graft-has open spaces that are twice as large as the skin
3:1 graft-has open spaces that are three times as large as the skin.
The larger the meshing ratio, the larger the surface area that can be covered by the graft. However, the downside is that larger meshed grafts result in more scarring than smaller meshed grafts or sheet grafts.
After harvest, the meshed graft is laid over the wound, dermis side down. It's usually secured with surgical staples, but sutures, biologic glue, or adhesive strips may also be used.
So how do you care for a meshed partial-thickness graft? Let's take a look at care tips next. For how to care for a partial-thickness sheet graft and its donor site, see "The full story on full-thickness skin grafts" from our January/February 2008 issue. (The care of sheet grafts and donor sites is the same for both full- and partial-thickness grafts.)
Dressed for success
Compared with sheet grafts, partial-thickness meshed grafts are less susceptible to fluid collection because the fluid drains from under the graft through the meshed openings. Also, meshed grafts are slightly more pliable than sheet grafts, so they tend to be less susceptible to shear. The biggest difference between the two, however, is that a meshed graft doesn't immediately close the wound upon application because of the open areas in the graft. This means that meshed grafts require dressings with antimicrobial action.
In the OR, following the application of a partial-thickness meshed graft, a nonadherent dressing is applied to the wound to prevent adherence of the outer dressings. Then, rolled gauze or a large, flat gauze dressing is soaked in an antimicrobial solution and placed over the nonadherent dressing. This is reinforced with a dry dressing followed by gauze netting or elastic wraps, with splinting as necessary. Alternatively, an antimicrobial dressing that isn't soaked in solution, such as a silver-impregnated dressing, is moistened and placed directly over the graft. There are also a few nonsolution, nonsilver dressings available to dress partial-thickness meshed grafts, but they aren't as commonly used.
If a dressing soaked in an antimicrobial solution is used, it's typically left in place for 3 to 5 days to avoid shear. Irrigate over the dressing every 6 to 8 hours, as needed, to keep the dressing moist. The first dressing change typically occurs on postoperative day three, although the graft may be left covered for up to 1 week. If the wound is complicated, the dressing may be removed on postoperative day one. After the first dressing change, change the dressing once or twice daily, as ordered, until the wound is healed, usually between postoperative day five and seven. Staples or sutures are typically removed on postoperative day five. The graft is then treated with moisturizing lotion and a dry dressing.
If a silver-impregnated dressing is used, it may remain in place for 3 to 5 days. Moisten the dressing every 4 to 8 hours because the silver, which provides the antimicrobial action, must be moistened to be active. The first dressing change typically occurs on postoperative day three, but the dressing may be left in place for up to 1 week or may be changed as soon as postoperative day one. After the first dressing change, the dressing is changed once a day, as ordered, until the wound is healed. Once the wound is healed, it's treated with moisturizing lotion.
After the wound is completely healed, teach your patient to stay out of the sun for 1 year, wear protective clothing, and use sun block with a high SPF on the graft site. He should keep the graft site moisturized and avoid subjecting it to extremely hot or cold temperatures and trauma.
Are there complications to watch out for? That's up next.
No need to get complicated
Although rare, complications, such as a hematoma (the collection of blood under the graft) or graft shear, may occur. Let's take a closer look.
If your patient experiences a hematoma, the health care provider will use a cotton swab to roll the blood out from underneath the graft. Occasionally, the health care provider may need to lift up the graft to physically remove an adherent hematoma.
Graft shear may occur if the graft isn't immobilized properly at the time of placement or if it doesn't adhere well to the underlying wound bed; during patient movement, therapy, or dressing changes; or if dressing movement causes the graft to shift off the wound bed. If graft shear occurs, the health care provider will replace the graft in its original position, if possible, and resecure it.
Case closed
Partial-thickness skin grafts can be used as intact sheet grafts or meshed grafts to cover large acute or chronic wounds. The procedure for harvesting and placing a meshed graft is relatively simple, and the resulting grafted wound and donor site heal quickly, making it a convenient and efficient method of wound closure.
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