Comparative effectiveness of mechanically and electrically powered negative pressure wound therapy devices: A multicenter randomized controlled trial David G. Armstrong, DPM, MD, PhD1; William A. Marston, MD2; Alexander M. Reyzelman, DPM3; Robert S. Kirsner, MD, PhD4 1. 2. 3. 4.
Southern Arizona Limb Salvage Alliance (SALSA), University of Arizona College of Medicine, Tuscon, Arizona Division of Vascular Surgery, Department of Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina Department of Medicine, California School of Podiatric Medicine at Samuel Merritt University, Oakland, California Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, Florida
Reprint requests: Dr. David G. Armstrong, Southern Arizona Limb Salvage Alliance (SALSA), University of Arizona College of Medicine, 1501 N. Campbell Ave. PO Box 245072, Tucson, AZ 85724, USA. Tel: +520 305 9393; Fax: +520 626 8140; Email:
[email protected] Manuscript received: June 16, 2011 Accepted in final form: January 17, 2012 DOI:10.1111/j.1524-475X.2012.00780.x
ABSTRACT This study was designed to compare the ultraportable mechanically powered Smart Negative Pressure (SNaP) Wound Care System (Spiracur, Sunnyvale, CA) with the electrically powered Vacuum-Assisted Closure (VAC) Therapy System (Kinetic Concepts, Inc. [KCI], San Antonio, TX) in a multicenter, comparative efficacy, noninferiority-powered, randomized controlled trial. We enrolled 132 people with noninfected, nonischemic, nonplantar lower extremity diabetic and venous wounds. Each subject was randomly assigned (1:1) to treatment with either system in conjunction with appropriate off-loading and compression therapy. The trial evaluated treatment for up to 16 weeks or complete wound closure (defined as complete reepithelialization without drainage). Primary end point analysis of wound size reduction found that SNaP-treated subjects demonstrated noninferiority to the VACtreated subjects at 4, 8, 12, and 16 weeks (p = 0.0030, 0.0130, 0.0051, and 0.0044, respectively). Kaplan–Meier analysis showed no significant difference in complete wound closure between SNaP- and VAC-treated subjects at all time points. Device related adverse events and complications such as infection were also similar between treatment groups. These data support similar wound healing outcomes between the SNaP system and the VAC system in the population studied.
The armamentarium of advanced therapies for the treatment of acute and chronic wounds—a major health care concern1–4 —continues to grow. Negative pressure wound therapy (NPWT), the delivery of subatmospheric pressure for wound healing, is now routinely used to treat a variety of acute and chronic wounds including wounds due to diabetes mellitus, pressure ulcers, and traumatic wounds. There is significant evidence that NPWT improves granulation tissue formation, decreases time to heal, and reduces overall cost of treatment compared with standard dressings.5–9 The Vacuum-Assisted Closure (VAC) Therapy System (VAC, KCI, San Antonio, TX), the most widely used electrically powered NPWT system today, was the first commercially available NPWT device and remains the most studied NPWT system. In addition, in three randomized controlled trials, NPWT improved healing compared with moist wound care in wounds of patients with diabetes and venous insufficiency.5,6,8 Although these studies were not without limitations, NPWT is now commonly used to treat these types of wounds. Many NPWT devices that are similarly configured to the VAC Therapy System (i.e., have an electrical pump connected to an occlusive dressing) exist in the market. At the time of this article, there exist at least 14 manufacturers of NPWT devices, but the Agency for Healthcare Research and Quality report in 2009 found no published studies directly comparing one NPWT system with another nor published head-to-head comparisons that were able to identify a 332
significant distinction of one NPWT system or component over another.10 Recently, a novel NPWT device that utilizes mechanical power instead of electrical power to generate subatmospheric pressure was introduced.11 This device, called the Smart Negative Pressure (SNaP) Wound Care System (SNaP, Spiracur, Inc., Sunnyvale, CA), is a single-use device that utilizes specialized springs to generate a preset continuous subatmospheric pressure level for NPWT delivery. Eliminating the electrically powered pump helps address many potential constraints associated with traditional NPWT devices, making it theoretically better suited for use in the ambulatory setting. Previous studies have shown that negative pressure delivered by the SNaP system has similar characteristics to the VAC Therapy System in biomechanical testing and in an animal wound healing model.12,13 Most recently, a study comparing SNaP-treated patients with standard treatment protocols for refractory lower extremity ulcers showed improved healing time similar to studies using electrically powered NPWT devices.14 In an effort to address the dearth of comparative efficacy studies in wound healing in general and NPWT specifically, we proposed to directly compare the SNaP Wound Care System with the VAC Therapy System in the treatment of lower extremity chronic wounds in a prospective, multicenter, randomized controlled study design. Importantly, this study was designed as a noninferiority trial with predetermined primary Wound Rep Reg (2012) 20 332–341 © 2012 by the Wound Healing Society
