Expert Pointers On Negative Pressure Wound Therapy

Clinical Editor: Lawrence Karlock, DPM

Given the increasing use of negative pressure wound therapy (NPWT) to spur wound healing, our expert panelists return for the second part of this Q&A discussion on NPWT (see “Inside Insights On Negative Pressure Wound Therapy,” page 24, May issue). They offer specific pearls on the use of NPWT, how to combine the modality with skin grafts and silver dressings, and tips for avoiding wound maceration. Q: Do you have any pearls for using negative pressure wound therapy (NPWT)? A: Eric Travis, DPM, utilizes VAC therapy (KCI) mostly at 125 mmHg of continuous suction. For a fragile wound or one with heavy exudation, he lowers the amount of suction. Dr. Travis advises caution with wounds that have significant periwound maceration and necrosis. He notes that he uses VAC open sponge technology to treat tunneling wounds. To prepare wounds prior to grafting, he applies growth factor technology, namely Regranex (Johnson & Johnson), and Panafil (Healthpoint) with VAC technology. In such cases, Dr. Travis recommends daily dressing changes. He uses silver dressings like Silverlon (Argentum Medical) with VAC therapy as he says they essentially maintain a lower bacterial burden and promote wound healing. Dr. Travis says such a combination is most effective with grafting techniques. Desmond Bell, DPM, incorporates VAC therapy with compression dressings. He says this is effective in helping prevent accidental disruption of the VAC seal. Compression via an Unna boot can also help reduce inherent edema in the lower extremity and can expedite the removal of exudates, according to Dr. Bell. In addition, Dr. Bell says wrapping a self-adhering bandage around the VAC tubing and subsequently securing it to the self-adhering outer wrap of the Unna boot can help prevent accidental pulling or catching of the tubing. For Lee Rogers, DPM, the most important pearl is knowing the proper wound in which to use NPWT. As he says, NPWT is best suited for deep, complicated wounds that require granulation tissue formation or enhancement of this tissue. Negative pressure wound therapy is not going to improve a wound that is shallow and granular, asserts Dr. Rogers, as such a wound is already at the desired endpoint. He notes the importance of thoroughly debriding the wound of necrotic and fibrotic tissue prior to using NPWT. Dr. Rogers suggests that one can also use NPWT in difficult locations such as interspaces between toes or around external fixation devices. Robert Frykberg, DPM, uses NPWT therapy frequently. He includes a TRAC Pad (KCI) on the top of the foot for plantar wounds and also uses NPWT in conjunction with tissue substitutes. Q: Do you ever combine NPWT with skin graft substitutes? Do you have any special technique? Do you combine negative pressure with silver dressings? A: Dr. Bell routinely uses VAC therapy in both pre- and post-graft settings. He calls it “an excellent adjunctive modality,” along with surgical debridement, to facilitate wound bed preparation prior to applying the graft. When using skin substitutes, Dr. Bell secures the graft with steri-strips and then covers the graft with Mepitel. He notes that Mepitel offers a silicone, porous non-stick dressing which will not disrupt the graft. Dr. Bell says Mepitel also provides an interface between the VAC sponge and the graft, which prevents suction of the graft into the sponge. He turns the VAC setting down to 75 mmHg of pressure on a continuous setting, and stops VAC therapy when the amount of exudate in the canister is minimal. Dr. Bell says the primary reasons for skin substitute failure are exudate and bacteria. He says VAC therapy can play an essential role in successfully absorbing the graft into the wound. Dr. Travis feels VAC therapy is unique and most advantageous to skin grafting in the lower extremity. He has used NPWT with skin grafts, mostly split thickness skin grafts (STSG), and skin graft substitutes like Alloderm or Graft Jacket (Wright Medical) as well as dermal substitutes such as Dermagraft (Advanced BioHealing) and Apligraf (Novartis). Dr. Travis says his selection of STSG versus allograft is based on the patient as well as the wound’s location, appearance and history. Using VAC therapy with skin grafting techniques appears to potentiate graft healing and adherence, eliminates fluid collection beneath the graft and helps protect the graft site from trauma, all of which commonly cause graft failure, according to Dr.

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