With the growing popularity of negative pressure therapy for treating wounds, one expert offered some advice for success at a meeting of the World Union of Wound Healing Societies.

Negative pressure wound therapy (NPWT) is indicated for chronic open wounds (diabetic and pressure ulcers),

acute and traumatic wounds, flaps and grafts, and subacute wounds. It works to speed healing in a number of ways, said Anne Dompmartin, M.D., a dermatologist at the Centre Hospitalier Universitaire in Caen, France. NPWT controls wound fluid, thereby removing inhibiting factors, decreasing inflammatory-phase cytokines and increasing fibroblast cytokines. The applied mechanical force influences the shape and growth of tissues.

NPWT also controls bacterial colonization, improves local blood perfusion, and enhances granulation tissue. The adhesive dressings necessary to maintain constant negative pressure also promote a moist wound-healing environment--a well-documented approach for better healing.

The technique involves fitting a foam dressing to the wound. A tube connects the dressing to a suction pump, via a canister that collects exudates. An adhesive film dressing is applied over the foam to provide an airtight seal.

The optimal negative pressure appears to be 125 mm Hg. Several studies have shown that wounds treated with this level of pressure exhibit a significant increase in the rate of granulation tissue formation, compared with lower pressures, Dr. Dompmartin said.

The patient may experience pain during the treatment and when the dressing is removed. If pain persists during treatment, this is a sign to stop and examine the wound, she said. Syringing saline solution with a local anesthetic down the draining tube half an hour prior to removal may facilitate the process. Patients may also develop eczema and irritation at the site.

With diabetic wounds, it's important to start NPWT before any infection occurs in the subcutaneous tissue or bone, she said. The hyperkeratotic tissue around these wounds allows longer use of NPWT.

Because NPWT stimulates angiogenesis, it should not be used for malignancies. Similarly, it should not be used around exposed organs and vessels or for untreated osteomyelitis, necrotic tissue, and fistulas.

It is important to know the cause of a nonhealing chronic wound, to avoid using the therapy when it is contraindicated. "You must be sure that the patient will benefit and will heal quicker," she said.

She and her colleagues also have used NPWT for the debridement of chronic fibrinous wounds that have not responded to other therapies. Typically, they see a response around day 6.