Biomedical Engineering Reference
In-Depth Information
shearing, as well as to accelerate closure of meshed graft interstices. Numerous
options for graft dressings exist, including various topical agents in combination
with a graft immobilization strategy. The use of a non-adherent dressing such as
Conformant 2 (Smith & Nephew) along with an outer antimicrobial wet dressing
allows the overlying dressings to be periodically removed without dislodging the
graft from the wound bed. Bolsters consisting of cotton and greasy gauze are
employed to help grafts conform to concave wound surfaces and splinting of
extremities may be necessary for safe graft immobilization, especially over joints.
The Vacuum Assisted Closure system (Kinetic Concepts Inc., San Antonio,
Texas) is another option for graft fixation. Alternatively, an Unna boot can be
placed on both the upper and the lower extremity to immobilize the graft and
provide vascular support, allowing mobilization of the extremity in the immediate
postoperative period. Sheet grafts can be either left open to the air to allow
continuous monitoring and rolling (depending on the patient) or wrapped with dry
dressings, which can be removed if necessary to allow interval inspection and
removal of underlying blebs.
There are also various options for donor-site dressings. The ideal donor-site
dressing would not only minimize pain and infection but also be cost effective.
Greasy gauze and Acticoat (Smith & Nephew, Largo, Florida) are often employed
for this purpose. Typically, these dressings are left in place until the donor site re-
epithelializes, at which time the dressing is easily separated from the healed
wound. Op-Site (Smith & Nephew, Largo, Florida), a transparent polyvinyl
adherent film, is also commonly used.
With Op-Site, the underlying wound is easily examined without removal of the
dressing. however, intermittent drainage of the wound fluid that accumulates is
necessary. Op-Site does not work well over joint surfaces and concave or convex
areas (e.g. the back). Silver sulfadiazine in a diaper is an excellent covering for
buttock donor sites in children; dressing changes can be done with each diaper
change.
5.4
Principles of allogeneic skin grafts
As opposed to autografts, allograft skin is harvested from a cadaver. In the
following sections, unique issues related to allograft skin are discussed, including
the history of its use, relevant immunology and techniques for application.
5.4.1
History of allogeneic transplantation
The history of plastic surgery is intimately intertwined with that of transplantation.
Crucial contributions to the understanding of graft survival began in the early 20th
century (Herman, 2002). The limited survival of allogeneic and xenogeneic skin
grafts in humans was investigated by Schone and Lexer in the early 20th century.
They demonstrated that both types of grafts did not survive for more than 3 weeks
