Expert Pointers On Negative Pressure Wound Therapy

Clinical Editor: Lawrence Karlock, DPM
Travis. With VAC therapy and skin grafting techniques, he notes increased conformity between the graft and the recipient site. Further, Dr. Travis says the foot and ankle present a unique problem with conventional bolster dressings due to the combination of uneven contours with multiple planes of motion. He adds the bolster dressing is essential to secure a graft between two and five days, which is the period of inosculation and capillary ingrowth. However, Dr. Travis says this process can be interrupted on more difficult graft sites where a thin layer of fibrin is the main adherent and exudative fluid from unsecured grafts can ultimately cause graft failure. Dr. Rogers notes that VAC therapy is very useful as a bolster dressing over a STSG. He uses the VAC until the wound bed is completely prepared and granular. At this point, Dr. Rogers applies a meshed STSG covered with a non-adherent dressing like Adaptic (Johnson & Johnson), Xeroform or Mepitel in order to prevent the graft from adhering to the foam. He uses normal pressure (125 mmHg) for VAC therapy on a continuous cycle and leaves it undisturbed for five days. As Dr. Rogers notes, this maintains the graft in constant, even pressure with the wound bed and prevents hematoma or seroma formation. After five days, Dr. Rogers says one can carefully remove VAC therapy and apply a dressing of choice until the wound heals or, in some cases, requires a second STSG. Vacuum-assisted closure therapy has increased the rate of graft uptake success for Dr. Travis’ patients. He initially uses sharp debridement or mechanical debridement with the Versajet (Smith & Nephew) to achieve a uniform and granular base, and employs a pulse lavage system to irrigate the wound. He meshes his STSG and acellular allografts to a 1:1.5 ratio and secures them to a final position with 4-0 nylon or staples. Dr. Travis then applies a permeable dressing. He prefers the Silverlon light dressing soaked in mineral oil or Adaptic. Dr. Travis says one should cut the polyurethane dressing slightly larger to fit the boundary of the recipient site. Then he advises physicians to cut the plastic tubing and place it within the foam dressing. Then the adhesive film accompanying the system should cover the graft site and surrounding skin, according to Dr. Travis. He advocates leaving the VAC dressing on the graft site for seven days with daily clinical inspection. Dr. Travis says if patients are able to tolerate ambulation, one may use a lower leg walking boot due to the tight adherence of the graft to the recipient bed with the VAC dressing. After day seven, he says one should inspect the graft. Dr. Travis continues VAC therapy if he thinks it is necessary. If he sees sufficient graft uptake, he discontinues VAC therapy and replaces it with a moistened Silverlon dressing. Dr. Travis says patients seem to do well with this protocol. Dr. Frykberg will raise the pressure if necessary when using NPWT with skin grafts. He combines NPWT with silver dressings but not continuously. Dr. Rogers notes that KCI now makes a foam that is impregnated with silver, saying it is only approved for use in acute care settings. Dr. Bell has utilized silver dressings over the Mepitel and between the black sponge for additional control of bacteria in the event that the VAC seal is inadvertently compromised (causing pooling of fluid in the wound). Q: How do you avoid maceration of the wound edges? A: Dr. Rogers advises properly cutting the foam so it does not overlap the wound edges, saying it makes a big difference. He also suggests outlining the wound with the VAC drape adhesive to protect the periwound area as he has seen some wound nurses do. In wounds with copious drainage or those in difficult locations, it may not be possible to avoid maceration. In these cases, Dr. Rogers suggests not reapplying VAC therapy for three to four days and perhaps applying Betadine to the wound edges under a wet-to-moist dressing. To avoid maceration, Dr. Frykberg advises cutting the foam to fit the wound. Sometimes he will use a hydrocolloid border around the wound. In wounds with heavy exudation, Dr. Travis notes it is difficult to avoid maceration. He notes the importance of getting a good seal with the negative pressure dressing. If the skin around the wound is fragile, he reinforces the area with Duoderm (Convatec), applying it to the area around the wound and applying the adhesive film over that.

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