Combination of Negative Pressure Wound Therapy and Acoustic Pressure Wound Therapy for Treatment of Infected Surgical Wounds: A
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Infected wounds are difficult to treat and often require “advanced” wound healing modalities to supplement conventional wound care using moist dressings and topical agents.1 In these wounds, the presence of devitalized tissue and bacterial infection slows both the granulation process and the progression of wound closure.2 Two advanced wound-healing modalities apply forms of mechanical pressure to the wound tissue that is intended to promote healing by stimulating cellular proliferation. Negative pressure wound therapy (NPWT) employs an open-cell, foam dressing with adhesive drape connected to a vacuum pump that applies either intermittent or continuous subatmospheric pressure to the wound tissues. Acoustic pressure wound therapy (APWT) delivers ultrasound-generated acoustic pressure to wound tissues via a fine mist of sterile saline.
Whether these two therapies stimulate the cellular activity necessary for wound healing is not definitively known. Regardless, published studies1,3 of NPWT and APWT have reported noteworthy improvements compared to conventional wound care in outcomes such as time to wound closure, proportion of wounds closed, and volume or area reduction. It should be noted that the preponderance of evidence supporting NPWT and APWT comes from case series reports and small randomized trials.1,3 Negative pressure wound therapy is specifically associated with reduced drainage from wounds with large amounts of exudate but is not considered a debridement modality.4 Conversely, APWT is not known for reducing drainage per se but is indicated for cleansing and maintenance debridement by removing yellow slough, fibrin, tissue exudates, and bacteria.
Using a combination of NPWT and APWT in a series of infected wounds post surgery or surgical debridement was evaluated at a 60-bed, acute rehabilitation hospital.
Six patients with large, infected wounds of surgical origin with serosanguineous exudate were treated with a combination of NPWT (V.A.C.® Kinetic Concepts Inc., San Antonio, TX) and APWT (MIST Therapy® System, Celleration, Inc. Eden Prairie, MN). A summary of patient and wound characteristics, medical histories, and wound treatments is provided in Table 1. Infections were confirmed by swab culture. Six wounds were in need of therapy to remove devitalized tissue and microbial infection, as well as promote granulation tissue formation and, ultimately, wound closure.
After unsuccessful attempts at debridement using wet-to-dry dressings daily over a period of 1 to 3 weeks, a combined approach using NPWT and APWT was pursued. Before initiating NPWT and APWT, the wounds had been present and nonhealing for anywhere from 11 days to 8.5 weeks. In accordance with the manufacturer’s clinical guidelines, NPWT dressings were applied with continuous pressure at 125 mm Hg and dressings were changed three times per week. Acoustic pressure wound therapy was administered three times per week at the same visits as the NPWT dressing changes; APWT treatment duration (minutes per session) was based on wound area per the manufacturer’s recommended treatment algorithm (ie, longer times for larger wounds). No other wound care modalities were administered during the study period.
As shown in Table 1, NPWT and APWT were administered concurrently over treatment periods ranging from 4 to 12 weeks; all but one patient received 8.5 weeks of treatment or less.