Sound Evidence - May 2008 - (Page 4) depth at end of treatment was not measurable due to hypergranulation in most of the wound bed (NPWT was continued in this wound until very small areas of bony presence were covered.) Surface area of the wounds was reduced by 82% to 100%, with the exception of the hypergranular wound, which was reduced by 60%. Serosanguineous wound drainage was reduced from copious/large to minimal/small in three wounds, copious to moderate in one wound, and remained unchanged in two wounds (one large, one moderate). Wound healing in patient 2 is shown in Figure 1a-c. supporting “modern” dressings (ie, foam, bead, alginate, or hydrocolloid) over traditional moistened gauze dressings in the treatment of postoperative wounds healing by secondary intention is also limited,6 with the exception of hydrocolloid occlusive dressings, which appear to be superior to conventional gauze dressings.10 Although pain, nursing time, and costs appear to be lower with the modern dressings (particularly foam compared with gauze), evidence of improved healing with modern dressings is inconsistent.5,6 Conclusion Discussion Optimal wound therapy for infected wounds post surgery or for surgical debridement has not been established.4-6 The patients in this series were at increased risk for slow healing of their postsurgical wounds due to multiple medical comorbidities (listed in Table 1). Understanding the reported clinical benefits of NPWT and APWT individually, we hypothesized that enhanced benefit might be attained from using the two therapies simultaneously in an effort to hasten healing in these medically complex patients. Negative pressure wound therapy is preferred for wounds with the substantial drainage seen in this case series. With the exception of one randomized prospective study of NPWT versus saline wet-to-moist dressing,7 the great majority of studies on NPWT have been consecutive case series in open wounds healing by secondary intention.1 This modality has been shown in these studies to reduce drainage in such wounds and some evidence suggests it may hasten healing.1,7 Additionally, preliminary data from a randomized, controlled study of NPWT for intact surgical wounds indicates significant drainage reduction with NPWT than with standard postoperative dressings (3.1 days versus 1.6 days; P = 0.03).4 The published studies of APWT to date have evaluated this noncontact, nonthermal, low-frequency ultrasound therapy in chronic wounds primarily of the lower extremities, including two randomized, controlled trials (one in diabetic foot ulcers8 and another in patients with chronic critical limb ischemia9). Again, these trials and published reports of consecutive case series suggest that APWT may speed healing of chronic wounds.3 The current paucity of evidence from high-quality trials is not limited to NPWT and APWT. Current evidence Six patients were treated with a combination of NPWT and APWT in an attempt to hasten healing of large, infected surgical wounds. Given the lack of a clear best practice for the care of such wounds, this small case series offers some insight into the potential healing outcomes that may be expected with combination NPWTAPWT therapy. Prospective, randomized trials are needed to evaluate this combination therapy in an evidencebased manner. - OWM References 1. Gregor S, Maegele M, Sauerland S, Krahn JF, Peinemann F, Lange S. Negative pressure wound therapy: a vacuum of evidence? Arch Surg. 2008;143(2):189–196. 2. Ennis WJ, Meneses P. Factors Impeding Wound Healing. In: Kloth LC, McCulloch JM, eds. Wound Healing: Alternatives in Management. Philadelphia, PA: F.A. Davis Company; 2002:68–96. 3. Unger PG. Low-Frequency, Noncontact, Nonthermal Ultrasound Therapy: A Review of the Literature. Ostomy Wound Manage. 2008;54(1):57–60. 4. Stannard JP, Robinson JT, Anderson ER, McGwin G, Jr., Volgas DA, Alonso JE. Negative pressure wound therapy to treat hematomas and surgical incisions following high-energy trauma. J Trauma. 2006;60(6):1301–1306. 5. Lewis R, Whiting P, ter Riet G, O'Meara S, Glanville J. A rapid and systematic review of the clinical effectiveness and cost-effectiveness of debriding agents in treating surgical wounds healing by secondary intention. Health Technol Assess. 2001;5(14):1–131. 6. Vermeulen H, Ubbink DT, Goossens A, de Vos R, Legemate DA. Systematic review of dressings and topical agents for surgical wounds healing by secondary intention. Br J Surg. 2005;92(6):665–672. 7. Joseph E, Hamori CA, Bergman S, Roaf E, Swann NF, Anastasi GW. A prospective randomized trial of vacuum-assisted closure versus standard therapy for chronic nonhealing wounds. WOUNDS. 2000;12:60–67. 8. Ennis WJ, Foremann P, Mozen N, Massey J, Conner-Kerr T, Meneses P. Ultrasound therapy for recalcitrant diabetic foot ulcers: results of a randomized, double-blind, controlled, multicenter study. Ostomy Wound Manage. 2005;51(8):24–39. 9. Kavros SJ, Miller JL, Hanna SW. Treatment of ischemic wounds with noncontact, low-frequency ultrasound: the Mayo clinic experience, 2004-2006. Adv Skin Wound Care. 2007;20(4):221–226. 10. Singh A, Halder S, Menon GR, et al. Meta-analysis of randomized controlled trials on hydrocolloid occlusive dressing versus conventional gauze dressing in the healing of chronic wounds. Asian J Surg. 2004;27(4):326–332. May 2008 Vol. 54 Issue 5 53
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