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CME ONLINE Single-use Negative Pressure Wound Therapy Systems A Continuing Medical Education Activity Sponsored By Grant funds provided by Grant Funds Provided By Welcome to Single-use Negative Pressure Wound Therapy Systems (An Online Continuing Medical Education Activity) CONTINUING EDUCATION INSTRUCTIONS This educational activity is being offered online and may be completed at any time. Steps for Successful Course Completion To earn continuing education credit, the participant must complete the following steps: 1. Read the overview and objectives to ensure consistency with your own learning needs and objectives. At the end of the activity, you will be assessed on the attainment of each objective. 2. Review the content of the activity, paying particular attention to those areas that reflect the objectives. 3. Complete the Test Questions. Missed questions will offer the opportunity to reread the question and answer choices. You may also revisit relevant content. 4. For additional information on an issue or topic, consult the references. 5. To receive credit for this activity complete the evaluation and registration form. 6. A certificate of completion will be available for you to print at the conclusion. If you have any questions, please call: 720-748-6144. CONTACT INFORMATION: © 2013 All rights reserved Pfiedler Enterprises, 2101 S. Blackhawk Street, Suite 220, Aurora, Colorado 80014 www.pfiedlerenterprises.com Phone: 720-748-6144 Fax: 720-748-6196 Overview Wound healing is the complex and dynamic process of restoring disrupted cellular structures and tissues; it is essential for achieving optimal outcomes in patients with both acute and chronic wounds, as delayed healing or infections are major sources of clinical complications and economic consequences today. Negative pressure wound therapy (NPWT), which provides a localized vacuum to draw the edges of a wound together, while providing a moist environment, is often used to promote healing of acute and chronic wounds. Today, technological advancements in single-use NPWT systems provide the associated benefits of NPWT for treating patients in hospital and community settings, thereby expanding treatment options, improving outcomes, and potentially reducing costs of care. Physicians involved in the care of patients with acute and chronic wounds should be aware of the new options for providing NPWT to promote effective wound healing. This continuing medical education activity will outline the historical evolution of negative pressure wound therapy. The process of wound healing and science behind NPWT will be reviewed. The incidence and impact of surgical site infections (SSIs) and delayed healing in high risk patients and procedures will be discussed. The indications, contraindications, and general guidelines for use for single-use NPWT systems will be outlined. A review of the literature citing research studies that demonstrate the clinical and cost effectiveness of NPWT will be presented. Key aspects of coding for reimbursement will also be discussed. Finally, physician considerations related to the use of NPWT systems will be reviewed. Objectives Upon completion of this continuing medical education activity, the participant should be able to: 1. Summarize the evolution of negative pressure wound therapy. 2. Explore the process of wound healing. 3. Explain the science of negative pressure wound therapy. 4. Review the incidence of SSIs and delayed wound healing in high risk patients and procedures. 5. Describe the indications and contraindications for single-use NPWT systems. 6. Identify the risk factors to consider before NPWT use. 7. Specify the guidelines for use for single-use NPWT systems. 8. Discuss evidence-based research specific to patient outcomes. 9. Analyze the cost effectiveness of NPWT systems, including coding for reimbursement. 10.Evaluate physician considerations from wound assessment to discontinuation of NPWT. 3 Intended Audience This continuing medical education activity is intended for physicians and other health care professionals who are interested in learning more about the wound healing process and the role of single-use negative pressure wound therapy systems to promote effective wound healing and reduce costs of care. Statement of Need This continuing medical education activity provides an opportunity for physicians to gain a perspective on NPWT therapy for complex wounds in general and an update on the technology of single-use NPWT systems in particular; an overview of wound healing and the impact of NPWT on the healing process; the consequences of SSIs related to wound healing; clinical indications and contraindications related to NPWT therapy; and knowledge of cost effectiveness and coding for reimbursement of NPWT systems. Professional Practice Gaps Physicians need to gain knowledge of the fundamentals of NPWT therapy for complex wounds; improved patient outcomes for acute and chronic wounds with NPWT therapy; the clinical considerations for application of single-use NPWT therapy based on evidence-based guidelines; and the cost effectiveness of NPWT therapy. CONTINUING MEDICAL EDUCATION CREDIT INFORMATION Instructions • This booklet is intended as an online activity. Please take the following steps to complete this activity: • Read the overview and objectives for this educational activity and compare them with your own learning objectives. • Read the booklet, paying particular attention to those areas that reflect the objectives. • Consult the glossary or a dictionary for definitions of unfamiliar words. • Complete the post-test. If some areas are unclear, review those sections of the booklet. • For further information, consult the References/Suggested Readings/Bibliography. Credit Information Accreditation This activity was planned and implemented in accordance with the Essential Areas and Policies of the Accreditation Council for Continuing Medical Education (ACCME). Pfiedler Enterprises is accredited by the Accreditation Council for Continuing Education (ACCME) to provide continuing medical education for physicians. 4 Credit Designation Pfiedler Enterprises designates this enduring activity for a maximum of 2.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Disclaimer Accredited status as a provider refers only to continuing medical education activities and does not imply endorsement of any products. Release and Expiration Date This continuing medical education activity was planned and provided in accordance with accreditation criteria. This material was originally produced in December, 2013 and can no longer be used after December, 2015 without being updated; therefore, this continuing education activity expires in December, 2015. Support Grant funds for the development of this activity were provided by Cardinal Health. Planning Committee/Authors/Reviewers Mark E. Chariker, MD, FACSLouisville, Kentucky Associate Clinical Professor of Surgery University of Louisville Department of Plastic and Reconstructive Surgery Medical Director Louisville Surgery Center Raymond Dunn, MD, FACS Associate Professor Department of Surgery, Division of Plastic Surgery Associate Professor, Department of Anatomy and Cell Biology, Chief, Division of Plastic Surgery, University of Massachusetts Medical Center Worcester, Massachusetts Charles K. Lee, MD, FACS Assistant Clinical Professor of Surgery Division of Plastic & Reconstructive Surgery The University of California at San Francisco Director of L Plastic Surgery - Form & Function San Francisco, California 5 Julia A. Kneedler, RN, MS, EdD Chief Executive Officer Pfiedler Enterprises Aurora, Colorado Carol J. Wilcox, MT (ASCP), MA, BS Consultant Pfiedler Enterprises Aurora, Colorado Disclosure of Relationships with Commercial Entities for Those in a Position to Control Content for This Activity Pfiedler Enterprises has a policy in place for identifying and resolving conflicts of interest for individuals who control content for a CME activity. Information below is provided to participants, so that a determination can be made if identified external interests or influences pose potential bias in content, recommendations or conclusions. The intent is full disclosure of those in a position to control content, with a goal of objectivity, balance and scientific rigor in the activity. For additional information regarding Pfiedler Enterprises’ disclosure process and our CME Advisory Committee members, visit our website at: http://www.pfiedlerenterprises.com/disclosure Disclosure includes relevant financial relationships with commercial interests related to the subject matter that may be presented in this CME activity. “Relevant financial relationships” are those in any amount, occurring within the past 12 months that create a conflict of interest. A commercial interest is any entity producing, marketing, reselling, or distributing health care goods or services consumed by, or used on, patients. Activity Planning Committee/Authors/Reviewers: Mark E. Chariker, MD, FACS No conflicts of interest Raymond E. Dunn, MD, FACS Grant/Research Support – Covidien Clinical Consultant – Covidien, Bard, Smith & Nephew Charles K. Lee, MD, FACS Speaker’s Bureau – Smith & Nephew Julia A. Kneedler, RN, MS, EdD Co-owner of company that receives grant funds from commercial entities Carol J. Wilcox, MT (ASCP), MA, BS No conflicts of interest 6 PRIVACY AND CONFIDENTIALITY POLICY Pfiedler Enterprises is committed to protecting your privacy and following industry best practices and regulations regarding continuing education. The information we collect is never shared for commercial purposes with any other organization. Our privacy and confidentiality policy is covered at our website, www.pfiedlerenterprises.com, and is effective on March 27, 2008. To directly access more information on our Privacy and Confidentiality Policy, type the following URL address into your browser: http://www.pfiedlerenterprises.com/privacypolicy In addition to this privacy statement, this Website is compliant with the guidelines for internet-based continuing education programs. The privacy policy of this website is strictly enforced. CONTACT INFORMATION If site users have any questions or suggestions regarding our privacy policy, please contact us at: Phone:720-748-6144 Email: [email protected] Postal Address: 2101 S. Blackhawk Street, Suite 220, Aurora, CO 80014 Website URL: http://www.pfiedlerenterprises.com 7 Introduction Wound healing is a complex, highly organized defensive response by an organism to tissue disruption; in the absence of infection, mechanical interferences, or certain disease processes, it is a highly reliable process.1 Both the human and economic costs of nonhealing wounds are major health care concerns today; in this regard, advances in wound care technology have demonstrated clinical benefits in terms of healing and improved patient quality of life.2 Today use of NPWT in the community has grown and thus benefits the patient as well as the health care system by providing quality care in the patient’s home and other alternative care settings. Historical Evolution of Negative Pressure Wound Therapy Definition of NPWT3 Negative pressure wound therapy is the application of subatmospheric pressure in a closed drainage system to a wound; it is recognized as an accepted and advanced option in the treatment of wounds.4 This technology applies a localized vacuum to facilitate excess wound drainage removal, draw the edges of a wound together, while providing a moist environment conducive to rapid wound healing. NPWT systems are comprised of a vacuum pump, drainage tubing, either a foam or gauze wound dressing, and an adhesive film dressing that covers and seals the wound. The pump may be stationary or portable (portable pumps are multi use, similar to stationary; disposable units are single-use) and may rely on either AC or battery power; it allows for regulation of the suction strength, has alarms to indicate loss of suction, and typically has a replaceable collection canister. The vacuum source creates either intermittent or continuous negative pressure inside the wound to remove fluid, exudates, and any infectious materials in order to prepare the wound for optimal healing and closure. The dressing sets may contain either foam or gauze dressing that will be placed in the wound and an adhesive film drape for sealing the wound. The drainage tubes are available in various configurations, depending on the dressings used or the wound being treated. As will be discussed, NPWT is used for chronic wounds that have been resistant to other forms of wound care and for acute wounds by promoting healing through granulation tissue formation and reepithelialization (i.e., secondary intention); therefore, it can be used as either the primary or secondary line of treatment, depending on the type of wound. Historical Development of NPWT The history of NPWT dates back to 1947 when surgeons in Russia used wall suction and gauze for postoperative wound exudate.5 In 1952, closed suction was used prophylactically as a postoperative measure to reduce complications. Between 1986 and 1987, five “Kremlin papers” reported that closed suction was an effective strategy for reducing wound healing time; decreasing hospitalization; and reducing bacterial counts in purulent wounds, with the use of wall suction and gauze to create a negative pressure to evacuate exudate from postoperative wounds.6 8 Long before NWPT was available, vacuum systems (e.g., Jackson-Pratt drains) were used to remove fluid from cavities and suture lines. In 1989, Chariker, et al published their findings regarding the effectiveness of NPWT in wound healing.7 These investigators used negative pressure applied with a Jackson-Pratt drain with the gauzetechnique in seven patients with fistulas; their results demonstrated reduced morbidity, improved wound contracture and reepithelialization, as well as a reduction in the use of nursing resources and costs. The use of polyurethane foam with a mechanical vacuum pump was pioneered during the 1990s by Drs. Louis Argenta and Michael Morykwas of Wake Forest University School of Medicine.8 These investigators reported their results using a new subatmospheric pressure technique: vacuum-assisted closure (VAC) in 300 wounds (175 chronic wounds, 94 subacute wounds, and 31 acute wounds).9 The VAC technique entailed placing an open-cell foam (ROCF) dressing into the wound cavity and applying a controlled subatmospheric pressure (125 mmHg below ambient pressure). The results showed that 296 wounds responded favorably to subatmospheric pressure treatment and had an increased rate of granulation tissue formation. The wounds were treated until they were completely closed and were covered with a split-thickness skin graft (STSG) or a flap was rotated into the healthy, granulating wound bed. This technique removes chronic edema, leading to increased localized blood flow; the applied forces result in the enhanced formation of granulation tissue. Therefore, the authors concluded that VAC is an extremely efficacious modality for treating chronic and difficult wounds. A line of products based on the research conducted by Drs. Argenta and Morykwas was developed and patented; it received approval by the United States Food and Drug Administration (FDA) in 1995.10 In 2004, the United States FDA approved a system that uses a vacuum chamber rather than a foam dressing, based on research performed in Russia during the 1980s. The Argenta, Morykwas patents were subsequently invalidated in 2010. NPWT is also a useful adjunct in treating patients with abdominal compartment syndrome as a means to control intra-abdominal pressures; reductions in morbidity rates and complications due to an open abdomen have been noted.11 In addition, treatment with NPWT has also resulted in a high rate of successful abdominal closure.12 An early method of NPWT for abdominal compartment syndrome (and one that is still used today) includes packing the abdomen with towels, covering the bowel with a 3 liter Bogota bag innovated by Dr. Borreaz, attaching drains to wall suction, and sealing off the wound using an iodine-impregnated adhesive surgical drape. Over the past 15 years, NPWT has become a commonly used treatment modality for a wide variety of complex wounds.13 NPWT works through mechanisms that include fluid removal, drawing the wound together, microdeformation, and moist wound healing; its use has dramatically changed the way complex wounds are treated, as several clinicians have noted a dramatic response when NPWT technology has been used. 9 Negative pressure wound therapy technology continues to evolve.14 For example, new device and dressing features have been added that not only make systems safer and more efficient, but more user-friendly in care settings other than hospitals, including rehabilitation centers, long-term care facilities, and patients’ homes. For example, NPWT has been used to improve the clinical outcomes of both skin and biomatrix grafts.15 Negative pressure wound therapy has become a well-established method for bolstering skin grafts to recipient beds; it is also being used more frequently over biomatrices improve overall skin graft outcomes. Using reticulated open cell foam (ROCF) has also become a well-established method for bolstering skin grafts to recipient beds; it is also being used in skin grafts and biomatrices is to optimally prepare the wound surface for graft acceptance and to enhance post-graft adherence and survival. Skin grafts generally fail as the result of shear forces or the development of a hematoma, seroma, or infection. The application of negative pressure conforms to the wound surface; this helps to stabilize the skin graft and helps prevent shearing of the graft on the wound surface. Removal of exudate decreases the risk of hematoma and seroma formation, while helping to prevent contamination. Increased granulation facilitates revascularization and attachment of the graft to the wound bed. The same mechanism of action by which NPWT helps skin grafts can also be applied to incision management. The latest addition in negative pressure technology is an NPWT system directed at surgical incision management, which was approved in late 2010.16 Surgical incisions have traditionally been closed by primary intention with the use of sutures, staples, adhesive surgical tape strips, tissue adhesives, or a combination of these methods. Sutures and staples are tension devices that concentrate the spreading force to small points along the incision; these tension points may lead to ischemia and potentially tissue necrosis. NPWT technology for incision management is intended to manage the environment of clean, closed surgical incisions (either sutured or stapled) that continue to drain by maintaining a closed environment and removing exudate through the application of negative pressure. This type of system consists of a singleuse negative pressure therapy unit, a small canister, and dressing, which is specifically designed for application over clean, closed sutured or stapled incisions. There are several advantages of an NWPT system for incision management, including both biomechanical and physiologic benefits; for example, the use of NPWT holds the closed incision edges together, which helps realign and reduce tensile forces across the incision. Other physiologic benefits include facilitation of fluid flow and protection of the incision from external contamination. To assess the benefits of this type of NPWT system, two computer models were used to study the influence of this therapy on the environment surrounding a closed incision. Skin tension was assessed before and after negative pressure (set at -125mm Hg) was applied. When no dressing was used, the tensile loads across the incision were concentrated at the sutures; when an incision management system dressing was used, the tension loads were evenly distributed across the incision plane and there was no local shear of the tissue. These results demonstrated that NPWT used for incision management realigned and reduced the tensile forces across the incision and therefore may assist in restoring more natural tension patterning across a healing incision. 10 Today, single-use, disposable NPWT systems that combine the associated benefits of NPWT with the simplicity of an advanced wound care dressing for small to medium size wounds with low to moderate levels of exudate represent a significant advancement in wound healing and contribute to cost-effective, quality care. Single-use systems that combine NPWT with integrated continuous irrigation are not possible because they lack a big container to hold a large volume of fluid. The clinical benefits of continuous irrigation technology in standard pumps include:17 • A controlled delivery of appropriate topical wound treatment solutions and suspensions; • Provision of beneficial fluids to keep wounds clean and moist and also facilitate removal of infectious materials; • Decreased tissue in-growth on foam dressings; • Reduction in damage to healthy tissue during dressing changes; • Increased patient comfort during and between dressing changes; • Reduction in bioburden issues and biofilm development; and • Protection of the dressing seal. The Wound Healing Process In order to understand the role of NPWT in promoting optimal patient outcomes, it is helpful to review the types of wounds and the wound healing process. Types of Wounds18 There are two categories of wounds: acute and chronic. • Acute wounds are traumatic or surgical wounds and typically progress through the healing process at a predictable rate from insult to closure. • Chronic wounds, which begin as acute wounds, do not move through the predictable phases of wound healing and therefore do not resolve over a reasonable period of time, regardless of the cause. Changes that occur within the molecular environment of a chronic wound (e.g., high levels of inflammatory cytokines, proteases lower levels of growth factors, some metalloproteinases destroy the collagen matrix in chronic wounds) are not conducive to healing because they terminate the healing process and increase the potential for septic infections. The most common chronic wounds are lower extremity ulcers. Chronic venous insufficiency accounts for 80% to 90% of lower extremity ulcers and affects 2% to 5% of the population. Other types of chronic wounds include diabetic, arterial, burns, dermatitis, vasculitis, and radiation. With the increase in newly diagnosed cases of diabetes, treatment of neuropathic and pressure ulcers is expected to increase proportionately. Chronic wounds are seen in every medical specialty; moreover, the occurrence of non-healing wounds is expected to increase as the population ages, people with chronic diseases continue to live longer, and the nutritional needs of the body are not met. 11 Mechanisms of Wound Healing19 Wounds heal by the following three mechanisms: • Primary intention. Healing by primary intention occurs when wounds are created aseptically, with minimal tissue destruction and postoperative tissue reaction. Wounds that are closed with sutures or staples soon after the injury are examples of wounds that heal by primary intention. Because these wounds are created under aseptic conditions, healing is optimized and the process begins almost immediately. Healing by primary intention occurs under the following conditions: ◦◦ The edges of an incised wound in a healthy patient are promptly and accurately approximated. ◦◦ Contamination is minimized by adherence to strict aseptic technique. ◦◦ Trauma to the tissue is minimized. ◦◦ No tissue loss occurs. ◦◦ Upon completion of closure, no dead space remains to become a potential infection site. ◦◦ Drainage is minimal. • Secondary intention or granulation. Wound healing occurs by secondary intention in surgical wounds typically characterized by tissue loss and the inability to approximate the wound edges. This type of wound is typically not closed; it is allowed to heal from the inside toward the outer surface. The area of tissue loss gradually fills with granulation tissue; scar tissue is extensive due to the size of the tissue gap that must be closed. Wound healing by secondary intention • Tertiary intention or delayed primary closure. Healing by tertiary intention occurs when approximation of the wound edges is intentionally delayed after the injury or surgical procedure. This type of wound may require debridement and usually require a primary and secondary suture line (e.g., retention sutures). Closure may be delayed one to many days (generally 10 or less) for any of the following scenarios: ◦◦ Removal of an inflamed organ; ◦◦ Heavy wound contamination; nonviable or ischemic tissue; or ◦◦ The critical nature of the patient intraoperatively, e.g., a trauma patient that is hemodynamically unstable. ◦◦ Tissue swelling such as in compartment syndrome. 12 Phases of Wound Healing20,21 Wound healing refers to the body’s replacement of destroyed tissue by living tissue by regeneration and repair. Knowledge of the underlying physiology of the wound healing process is essential for effective wound management, as it enables the health care professional to distinguish healthy and unhealthy tissue and thereby assess the wound for proper healing and/or the development of complications. Healing of clean, fullthickness wounds is a complex biological process that occurs in three overlapping phases: inflammatory, proliferative, and remodeling phases, as described below (see Figure 1) and summarized in Table 1. Figure 1 – Phases of Wound Healing Remodeling Phase Proliferative Phase Inflammatory Phase 3 Days 14 Days 1 Year • Phase 1 – Inflammatory Phase (also called the reactive stage). Inflammation is a requirement for wound healing and is the vascular and cellular response to dispose of bacteria and other foreign material. This phase begins within minutes after an injury and is necessary to establish hemostasis and begin mobilization of the immune system. Increased blood flow to the area causes the wound to begin to clot. As the blood supply to the area increases, the basic inflammatory process begins. The increase in the number of leukocytes helps to fight bacteria in the wound area and, through phagocytosis, assist in removing damaged tissue. In this phase, an exudate containing blood, lymph, and fibrin begins to clot and loosely bind the severed edges of the wound together. The severed tissue is quickly glued together by strands of fibrin and a thin layer of clotted blood, which forms a scab; plasma escapes to the surface and forms a dry, protective crust. This seal assists in preventing fluid loss and bacterial invasion; however, in the first few days of the wound healing process, this seal has little tensile strength. The inflammatory phase usually lasts between 1 and 4 or more days. During this period, the edges of the skin may appear mildly swollen and slightly red due to the inflammatory process. • Phase 2 – Proliferative Phase (also called the regenerative or reparative stage). This phase begins within hours of an injury and allows for new epithelium to cover the wound. Epithelial cells migrate to and proliferate in the area of the wound, covering the surface of the wound in order to close the epithelial defect; this also provides a protective barrier, which serves as a mechanism to prevent fluid and electrolyte loss and to prevent the introduction of bacteria into the wound, thus reducing the 13 incidence of infection. As reepithelialization occurs, collagen synthesis and wound contraction are also taking place. Collagen synthesis produces fiber molecules that crosslink to strengthen the wound. Epithelial migration is limited to approximately 3 cm from the point of origin; this limited epidermal migration is why a larger wound may require skin grafting. Approximately 5 days after onset of the wound, contraction begins; it peaks at 2 weeks and gradually shrinks the entire wound. With a surgical wound, granulation tissue will form underneath the edges of the incision and are palpated as a hard ridge; this eventually resolves in the remodeling phase. • Phase 3 – Remodeling Phase (also called the maturation stage). This phase begins after approximately 2 to 4 weeks, depending on both the size and nature of the wound; it may last one year or more. During this final stage, scar tissue that has formed changes in terms of bulk, form and strength; this allows for the wound to be strengthened. Collagen production and breakdown started during the proliferative phase allows randomly deposited connective tissue to be arranged in linear and lateral orientation. As the scar ages in the remodeling phase, fibers and fiber bundles are more closely packed in a crisscross pattern, ultimately forming the final shape of the wound. At most, the tensile strength of scar tissue is never higher than 80% of that of nonwounded tissue. Table 1 – Summary of the Phases of Wound Healing22,23 Phase Time Period Events Inflammatory (Reactive) Phase 1 to 4 days • Inflammation - Vasodilation - Phagocytosis - Formation of a seal to assist in preventing fluid loss and bacterial invasion Proliferative (Regenerative or Reparative) Phase 5 days to 2 weeks Remodeling 2 - 4 weeks to (Maturation) Phase 1 year or more • Reepithelialization • Collagen synthesis • Wound contraction • Collagen refinement and remodeling - Resorption of Collagen III replaced with Collagen I; - Randomly deposited fiber and fiber bundles more closely packed in a crisscross pattern Factors that Interrupt the Wound Healing Process There are several factors that may impair or interrupt tissue repair and healing; these include the patient’s nutritional status, oxygenation level, and overall recuperative power, all of which are critical in tissue repair and healing.24 Both the inflammatory response and oxygen tension are dependent upon microcirculation to deliver vital components to the wound. A decrease in oxygen tension to the wound area inhibits fibroblast migration and collagen synthesis, thereby resulting in a reduction in the tensile strength of the wound. Nutritional status is also an important consideration in the wound healing process 14 because of the need for an adequate supply of protein, which is necessary for growth of new tissue. Protein is also required for the regulation of the osmotic pressure of the blood and other body fluids and the formation of prothrombin, enzymes, hormones, and antibodies. Other required nutritional elements include water; vitamins A, C, B6, and B12; iron; calcium; zinc; and an adequate calorie intake. Another important factor for the surgical patient is to maintain normothermia in the operating room (OR), because hypothermia contributes to vasoconstriction, which can have an adverse effect on wound healing. The wound healing process may also be interrupted by additional factors, including: • Poor surgical technique, i.e., rough handling of tissue causing trauma, which leads to bleeding and other conditions that may promote infection.25 Examples of surgical techniques that facilitate wound healing are achieving and maintaining adequate hemostasis; utilizing precise cutting and suturing techniques; using time efficiently in order to minimize wound exposure to air; eliminating dead spaces; and exerting minimal pressure with the use of retractors and other instruments. • Patient-related factors, such as:26 ◦◦ Age (both the very young and very old); ◦◦ Altered nutritional status (e.g., obesity, malabsorption syndromes, excessive alcohol intake, poor eating habits,malnutrition); ◦◦ Inadequate oxygenation due to cardiovascular, cerebrovascular and peripheral vascular, or respiratory impairments; ◦◦ Stress level; ◦◦ Poor hygiene; ◦◦ Smoking history; ◦◦ Autoimmune disorders, such as lupus erythematosus, multiple sclerosis, Crohn’s disease, and rheumatoid arthritis; and ◦◦ Preexisting conditions, e.g., anemia, cancer, chronic inflammatory disease, Cushing’s syndrome, diabetes, human immunodeficiency virus (HIV), peripheral vascular disease, peripheral neuropathy, radiation therapy. • Certain medications and herbal supplements.27 Impaired wound healing is a side effect of many drugs as well as supplements, because many types of drugs interact with certain phases of the healing process. Herbal medications should be taken into consideration preoperatively since many of them can inhibit platelet activity, increase blood pressure, or exacerbate the effects of anticoagulant medications. Because many patients do not consider herbal supplements to be “drugs,” it is important that the patient is asked specifically about these agents. Examples of various drugs and supplements that affect wound healing are outlined in Table 2. 15 Table 2 – Drugs and Supplements that Affect Wound Healing28 Drug/Supplement Antibiotics • Penicillin Effect • Interferes with the tensile strength of the wound by affecting the cross-linking of collagen Anticoagulants Leads to hematoma formation Anti-inflammatory agents, including steroids Suppresses inflammation Ibuprofen Suppresses protein synthesis Naproxen Suppresses epithelialization Inhibits the formulation of granulation tissue Increases the incidence of bleeding Aspirin Inhibits activation of platelets Warfarin (Coumadin®) Impairs blood clotting Chemotherapeutic agents Arrests cell replication Suppresses inflammation Suppresses protein synthesis Reduces white blood cell count Colchicine (Colcrys®; used in the treatment of gout) Arrests cell replication Feverfew (used for migraine headaches and rheumatoid arthritis) Inhibits platelet activity Guarana (used as a weight loss supplement; contains caffeine, theophylline, and theobromine, which are chemicals similar to caffeine) Decreases platelet aggregation Garlic Inhibits platelet aggregation Gingko Inhibits platelet activation Ginseng Inhibits platelet activation St. John’s Wort Inhibits neurotransmitter uptake Suppresses collagen transport Includes enzymes that affect warfarin and other drugs 16 Incidence of Surgical Site Infections (SSIs) and Delayed Wound Healing in High Risk Patients and Procedures Surgical Site Infections Surgical site infection is the most common cause of delayed wound healing in the surgical patient; there are several potential causes of SSIs, such as the patient’s susceptibility to and the severity of illness; microbial contamination by the patient’s own (i.e., endogenous) microflora; and exogenous wound contamination from the OR environment and/or personnel.29 Today, postoperative SSIs are primary sources of illness and, less frequently causes of death.30 Of the estimated 27 million patients who undergo surgery every year, approximately 500,000 will experience an SSI, accounting for one-quarter of the estimated 2 million hospital-associated infections in the United States annually. Patients who develop an SSI are hospitalized postoperatively for approximately 7 to 10 days longer and have a 2 to 11 times higher risk of death compared to patients without an SSI; 77% of deaths among patients with a surgical site infection are directly attributable to the infection. While the costs associated with an SSI vary, depending on the type of procedure as well as the type of pathogen, estimates range from $3,000 to $29,000 per infection; furthermore, SSIs are believed to account for up to $10 billion annually in health care expenditures. Therefore, reducing the incidence of SSIs could result in tremendous cost savings to the United States as a whole. National studies have defined the patients at highest risk for infection in general and in many specific operative procedures.31 For example, in orthopedics, tibial plateau, pilon, and calcaneal fractures are particularly noted for complications associated with infections and wound healing problems.32 Specifically, tibial plateau fractures are associated with infection rates that range from 5% to 80%, with a mean of approximately 27% with open reduction and internal fixation; pilon fractures have an incidence of deep infections ranging from 5% to 40%; and calcaneal fractures reporting deep infections range from 0% and 20%. According to the Centers for Disease Control and Prevention (CDC), the rate of women having Cesarean sections has increased by 53% from 1996 to 2007, reaching 32%, which represents the highest rate ever reported in the U.S and the upward trend continues today; moreover, 48% of women 40-54 years of age giving birth will have a Cesarean section.33 The SSI rate for Cesarean sections is as high as 3.82%; an SSI can add over $3,500 in additional costs of care to each procedure.34,35 Four pathogens (Staphylococcus aureus, coagulase-negative staphylococci, Escherichia coli, and Enterococcus faecalis) are responsible for over 56% of obstetrics/gynecology SSIs, including those in Cesarean sections.36 Because the clinical and economic burdens associated with SSIs are significant, federal initiatives are currently in place to incentivize hospitals and health care facilities to improve quality of care by reducing SSIs and other hospital-acquired conditions through limits on reimbursement as well as public reporting. The Deficit Reduction Act (DRA) of 2005 requires the identification of conditions that are high cost or high volume or both; 17 result in the assignment of a case to a diagnosis-related group that has a higher payment when present as a secondary diagnosis; and could reasonably have been prevented through the application of evidence-based guidelines.37 Effective for discharges occurring after October 1, 2008, the Centers for Medicare and Medicaid Services (CMS) no longer reimburses hospitals for the additional costs of care for cases in which one of the selected conditions was not present on admission; i.e., the case would be paid as though the secondary diagnosis were not present. Delayed Wound Healing Delayed wound healing also continues to be a clinical concern today with associated significant morbidity and impaired quality of life that consume substantial health care resources.38 Age-related changes and predisposing medical conditions, such as diabetes, can complicate the healing process which further increases the risks.39 In addition to surgical site infections, wound complications include seroma, hematoma, and wound or fascial dehiscence.40 Both hematomas and seromas can cause the incision to separate and predispose to wound infection, since bacteria can gain access to deeper layers and multiply uncontrolled in the stagnant fluid. Wound or fascial dehiscence is a partial or total disruption of any or all layers of an operative wound; it may be partial or complete in the superficial or deeper fascial planes. As outlined above, wound healing is a dynamic process that must occur in a precise and regulated manner; any interruptions, abnormalities, or prolongation in this process can lead to delayed wound healing or a non-healing chronic wound.41 Wounds that exhibit impaired healing, including delayed acute wounds and chronic wounds, generally have failed to progress through the normal phases of healing. These wounds frequently enter a state of pathologic inflammation due to a postponed, incomplete, or uncoordinated healing process. In the United States today, chronic wounds affect 6.5 million patients.42 It is estimated that more than $25 billion is spent every year on the treatment of chronic wounds; moreover, this burden is growing rapidly due to increasing health care costs, an aging population, and a dramatic rise in the incidence of diabetes and obesity. The Science behind Negative Pressure Wound Therapy The first step in effective wound healing is to either remove or correct any factor that impairs healing; many wounds will heal with good wound care that removes necrotic tissue, maintains a moist wound environment, and reduces the risk of infection.43 After these factors are addressed, some wounds will benefit further from adjunctive therapies, such as the application of negative pressure wound therapy (NPWT).44 Within the past decade, NPWT has shown promise in promoting the healing of both acute and chronic wounds, partial-thickness burns, diabetic and pressure ulcers, as well as skin grafts.45 There are five mechanisms by which the application of negative pressure to a wound may facilitate the healing process, as described below.46,47 • Wound retraction. Wound retraction under negative pressure brings the edges of the wound closer together, while at the same time putting mechanical stress on the tissue. This externally applied stress is believed to create microdeformations 18 in individual cells, which induce the production of cellular messengers responsible for increasing matrix synthesis and cell proliferation within the wound. • Stimulation of granulation tissue formation. Intermittent low pressure alters the structure of the cells in the wound bed, thereby triggering a cascade of intracellular signals that increase the rate of cell division and the formation of granulation tissue. • Continuous wound draining after adequate primary surgical debridement. Continuous wound draining with NPWT may help control infection by removing fluid that harbors bacteria, increasing oxygen used for bacterial destruction, improving antibiotic penetration, providing a moist environment that supports white blood cell function, and maintaining a closed system. NPWT can be used in infected wounds when combined with debridement and antibiotics. NPWT also removes substances that inhibit wound healing. By decreasing the high levels of inflammatory mediators in chronic wound fluid, NPWT also helps chronic wounds move from the inflammatory phase into the repair phase of healing. • Continuous removal of exudate. Continual removal of exudate from a wound may reduce tissue edema and optimize blood flow back into the wound bed. • Reduction of interstitial edema. Interstitial fluid, i.e., exudate, that accumulates in a wound may mechanically compress local capillaries and thus restrict blood flow into the wound. The application of NPWT may reduce edema by increasing blood flow velocity, thereby decreasing hydrostatic pressure and drawing more extracellular fluid into the vessels. Tissue compression by NPWT may also push fluid out of the interstitial space. By reducing edema, microvascular blood flow is increased and nutrient diffusion in the interstitial space is improved. Because the mechanism of action of NPWT is multimodal, it can achieve a broad range of treatment goals, including:48 • Management and protection of the wound – through improved fluid management, prevention of wound desiccation, and prevention of environmental insult • Preparation of the wound for surgical closure and progression of the wound by secondary intention – through improved quality of the wound bed (i.e., granulation tissue formation), contribution to infection management, and reduction of size and complexity of wound. • Improved outcome after STSG by splinting the wound and preventing postoperative complications, such as graft failure. • Improved patient comfort – by a reduction in wound pain, less frequent dressing changes, improved patient mobility, and management of wound exudate and odor. • Reduced costs as the result of faster progression to additional surgery/hospital discharge, shorter time to closure, reduced use of nursing resources and time, and prevention of wound complications. 19 Based on these mechanisms, the addition of negative pressure to a wound dressing results in numerous clinical benefits, such as:49 • Increase in local blood flow via enhancement of capillary blood flow; • Increase in angiogenesis; • Increase in the number of active fibroblasts and macrophages; • Enhanced epithelial cell migration; • Decrease in the number of dressing changes and subsequent reduction in damage to delicate new tissue, pain, desiccation, and exposure to infectious agents; • Provision of a moist, normothermic wound environment that allows more efficient epithelialization, growth factor synthesis and availability, as well as overall wound healing potential; • Decrease in shear forces to the graft via uniform wound bed immobilization; • Decreased seroma/hematoma of grafts and flaps; • Limitation of the zone of injury after acute orthopedic trauma; and • A splinting effect (sternal, abdominal). NPWT: Indications and Contraindications for Use Indications Negative pressure wound therapy is indicated for the treatment of:50 • Acute surgical and traumatic wounds; • Subacute and dehisced wounds; • Pressure ulcers (see Table 3 for a brief description of pressure ulcer stages); • Chronic and open wounds (e.g., venous stasis ulcers and diabetic foot ulcers); • Meshed grafts (to secure the graft in place and/or to accelerate the epithelialization of the donor site); and • An adjunct to skin grafts/flap procedures. 20 Table 3 – Pressure Ulcer Classification System51 Stage Description Stage I – Nonblanchable erythema Intact skin with non-blanchable redness of a localized area usually over a bony prominence The area may be painful, firm, soft, warmer or cooler in comparison to adjacent tissue May be difficult to detect in persons with dark skin tones May indicate “at risk” individuals (a heralding sign of risk) Stage II – Partial Thickness Skin Loss Partial thickness loss of dermis; presents as a shallow open ulcer with a red/pink wound bed, without slough May also present as an intact or open/ruptured serumfilled blister Presents as a shiny or dry shallow ulcer without slough or bruising, which indicates suspected deep tissue injury Stage III – Full Thickness Skin Loss Full thickness tissue loss Subcutaneous fat may be visible, but bone, tendon, or muscle are not exposed Slough may be present but does not obscure the depth of tissue loss May include undermining and tunneling Depth varies by anatomical location Stage IV – Full Thickness Tissue Loss Full thickness tissue loss with exposed bone, tendon, or muscle Slough or eschar may be present on some parts of the wound bed Often includes undermining and tunneling Depth varies by anatomical location Unstageable: Depth Unknown Full thickness tissue loss in which the base of the ulcer is covered by slough (yellow, tan, gray, green, or brown) and/or eschar (tan, brown, or black) in the wound bed Until enough slough and/or eschar is removed to expose the base of the wound, the true depth (and therefore the stage) cannot be determined Suspected Deep Tissue Injury: Depth Unknown Purple or maroon localized area of discolored intact skin or blood-filled blister due to damage of underlying soft tissue from pressure and/or shear The area may be painful, firm, mushy, boggy, warmer or cooler in comparison to adjacent tissue Specific wounds for which NPWT is used include:52 • Large trauma wounds with exposed bones, tendons, vessels, and closed joints. These types of large trauma wounds can be treated effectively using NPWT, because the pathogen-free environment will promote the formation of granulation tissue over these structures. The average duration of treatment is approximately two weeks. 21 • Large sacral ulcers. For large sacral ulcers, the contraction obtained with NPWT can enhance healing. To prevent infection of any undrained area, the dressing must access the cavity entirely. The average duration of treatment for large sacral ulcers is about three weeks • Post-sternotomy wounds. For these wounds, NPWT is indicated when the sternal bone is exposed and generally infected and a large open cavity exposes the anterior mediastinal area. The mean duration of treatment is variable depending on patient conditions and additional possible surgical wound management. • Post-surgical debridement. Following a surgical debridement, NPWT can be an effective method of treating these poorly vascularized wounds. In postoperative wounds of the abdominal wall, two different situations may be encountered; first, the existence of a parietal muscular defect and second, the need to close the peritoneal cavity. In the second situation, NPWT must be left in place for a period of time long enough to obtain uniform granulation tissue; once this occurs, a skin graft is usually proposed. • Tunneling wounds. This includes any wound that has a channel that “tunnels” from the wound into or through the muscle or subcutaneous tissue. More than one tunnel may be present and can be short and shallow or long and deep. Tunneling of a wound may occur as a result of infection, improper wound packing, concentrated pressure and shear forces where the tissue layers meet, or from prolonged inflammation in chronic wounds. Sometimes tunneling is discovered only on probing the wound. Foam may be used (but avoid foam in very narrow tunnels) and should be in contact with the wound bed up to the surrounding edges only. Avoid packing too tightly or placing friction on the wound edges. Change dressings every 48 hours for the first several days; when drainage decreases change dressings every 72 hours. Evaluation for effectiveness of treatment should include a 10% decrease in the wound after the first week or a 50% decrease in the wound in week four. NPWT has been used successfully on wounds with extensive tunneling.53 Single-use, disposable negative-pressure systems are recommended for patients with: • Venous stasis ulcers; • Lower extremity ulcers; • Pressure ulcers; • Lower extremity flaps; • Dehisced incisions (i.e., a condition in which the wound has a premature opening or splitting along natural or surgical suture lines because of improper healing); • Grafts; and • Incision management.54 ◦◦ As outlined above, an NPWT system intended for surgical incision management was recently approved; this type of system is most beneficial 22 when used in high risk patients on intact incisions in order to prevent nonhealing or dehisced wounds, rather than addressing these problems once they have occurred. Patients at high risk for wound dehiscence or infection are those with diabetes, obesity, edema, and other infections. Patients who are readmitted to the hospital because of a failed surgical incision are very challenging for health care providers and incur greater health care costs; the infection risk for dehisced wounds further increases when additional procedures to close the incision are required. Therefore, it is critical that patients at high risk for wound dehiscence are treated proactively to prevent negative outcomes. Preliminary studies have demonstrated a decrease in wound dehiscence, infection, and time to healing when an NPWT system for incision management was used. The use of NPWT for incision management is both appropriate and cost-effective, especially in high risk patient populations, as it may prevent edema, dehiscence, and infection, thereby resulting in a decreased length of stay for surgical patients and allowing for optimal management of surgical incisions. Contraindications55,56 Contraindications to the use of NPWT include, but are not limited to: • Inadequately debrided wounds (granulation tissue that will not form over necrotic tissue); • The presence within a treatment zone of severely ischemic tissue; • Necrotic tissue with eschar; • Malignancy in the wound (negative pressure therapy can contribute to cellular proliferation); • Untreated osteomyelitis or sepsis within the vicinity of the wound; • Exposed organs, bone, or blood vessels; • A non-enteric fistula or sinus tract;. • The presence of untreated coagulopathy; and • An allergy to any component required for the procedure. All devitalized or necrotic tissue must be debrided, the necessary surgical revascularization must be performed, and infection must be managed with either antibiotic therapy or with the excision of osteomyelitic bone prior to the application of negative pressure therapy. Grafting over exposed organs, blood vessels, tendons, nerves, bone, or implanted hardware requires the surgical interposition of vascularized tissue with or without a mesh barrier, either biologic or synthetic, if indicated. Single-use NPWT systems should not be used in anastomotic sites; for emergency airway aspiration; for pleural, mediastinal, or chest tube drainage; or as surgical suction. 23 Patient Risk Factors57 Physicians need to consider the following patient risk factors/characteristics before NPWT use: • Patients at high risk for bleeding and hemorrhage • Patients on anticoagulants or platelet aggregation inhibitors • Patients with: ◦◦ Friable vessels and infected blood vessels ◦◦ Vascular anastomosis ◦◦ Infected wounds ◦◦ Osteomyelitis ◦◦ Exposed organs, vessels, nerves, tendons, and ligaments ◦◦ Sharp edges in the wound (i.e. bone fragments) ◦◦ Spinal cord injury; exposed meningeal tissue of the brain or spinal cord (stimulation of sympathetic nervous system) ◦◦ Enteric fistulas • Patients requiring: ◦◦ MRI ◦◦ Hyperbaric chamber ◦◦ Defibrillation • Patient size and weight (under weight, obese) • Use near vagus nerve (bradycardia) • Circumferential dressing application • Mode of therapy – intermittent versus continuous negative pressure Single-use NPWT Systems: Sample Guidelines for Use In order to maximize the potential benefits of single-use NPWT systems, clinicians should understand the general guidelines for use, as outlined below. As with all medical devices, the manufacturer’s written instructions for the specific system should always be consulted and followed. System Overview/Components Single-use, disposable NPWT systems combine the associated benefits of NPWT with an advanced wound care dressing for small to medium size wounds with low to moderate levels of exudate. These systems typically consist of a small pump, which eliminates the need for a bulky canister (see Figure 2). In appropriate wounds, it may be applied quickly in just a few minutes. Pressure is applied to the wound surface in the range of -5 to -125 mm Hg; this is adjustable to higher pressures, depending on the specific device used.58 Many pumps are designed to maintain negative pressure wound therapy at -80 24 mmHg (nominal) ±20 mm Hg to the wound surface. Research demonstrates that the physiological effects are near maximal at -80 mm Hg.59,60 Figure 2 – Single-use, Disposable NPWT Pump Exudate is managed by the advanced dressing (see Figure 3) through a combination of absorption and evaporation of moisture through the outer film. In general, a single-use system is intended: • For use in wound sizes (surface area x depth) up to 400 cm3 which are considered to be low to moderately exuding. • To be used for a maximum of 7 days on low exuding wounds and 6 days on moderately exuding wounds. Therapy duration may be less than indicated if clinical practice or other factors (e.g., wound type, wound size, rate or volume of exudate, orientation of the dressing or environmental conditions) result in the need for more frequent dressing changes. Figure 3 – Single-use NPWT System Advanced Dressing 25 Wound Suitability Single-use NPWT systems should be used on wounds (e.g., acute wounds, chronic wounds, or skin grafts) which fit comfortably within the area of the pad, taking precautions on port positioning (i.e., on intact skin and not extending over the wound). The following general principles apply: • Depth. Wounds that are greater than 0.5 cm (¼ inch) in depth are likely to require a foam or gauze NPWT filler to ensure adequate treatment of all the wound surfaces. Wounds treated with the larger dressing sizes should generally be no more than 2 cm (4/5 inch) in depth. • Exudate. Single-use NPWT systems are intended for use on wounds where the level of exudate is low (nominally 0.6 gal of liquid exudate/cm2 of wound area per 24 hours) to moderate (nominally 1.1 gal of liquid exudate/cm2 of wound area per 24 hours); 1 gal of exudate is approximately equal to 1 L of exudate. When used on a moderately exuding wound, the size of the wound should generally be no more than 25% of the dressing pad area. Single-use NPWT systems expand the options for this therapy with at-risk procedures and high-risk patients, as outlined in Table 4. Table 4 – Options for Single-use NPWT Systems At-Risk Procedures High-Risk Patients Cardiothoracic surgery Diabetic Orthopedic surgery Obese Abdominal surgery Smokers Lower extremity bypass Hypertensive Poor vascular status Infection Immunocompromised Potential for postoperative swelling and oozing Poor nutrition Application:A sample of the general steps for the application of a single-use NPWT system components are outlined below. 1. Remove any excess hair to ensure close approximation of the dressing to the wound. If necessary, irrigate the wound with sterile saline and pat the wound dry. 2. Using clean technique, peel off the backing and place the dressing centrally over the wound to reduce the risk of wound fluid coming into contact with the port. The port should be uppermost from the wound (depending on the patient’s primary 26 position) and placed on intact skin not extending over the wound to prevent fluid pooling around the port and blocking the negative pressure. 3. Remove the remaining backing and smooth the dressing around the wound to prevent creasing (see Figure 4). Reposition the dressing as needed to ensure that the border is not creased. Figure 4 –Smooth Dressing around Wound to Prevent Creasing 4. After the dressing is securely in place, remove the pump and the batteries from the tray; insert the batteries and replace the cover. Note that the system is operating properly, as specified in the manufacturer’s instructions (e.g., after the batteries are inserted, proper operation may be indicated by flashing lights). 5. Connect the pump to the dressing according to the manufacturer’s instructions. Press the appropriate button to start the application of negative pressure and observe for proper operation (e.g., a flashing light may indicate that the system is working properly). Depending upon the size of the wound and the device used, the pump may take up to 30 seconds to establish negative pressure wound therapy (see Figure 5). If after the specified time the system has not established negative pressure wound therapy, observe for indication of an air leak according to the manufacturer’s instructions. Figure 5 – Connect Pump to Dressing; Observe for Proper Operation 27 6. If using a skin protectant on patients with fragile skin prior to application of the fixation strips, wipe the area surrounding the dressing and allow skin to dry. 7. If supplied, apply the fixation strips to each of the four sides of the dressing; remove the top carrier on the strip after each one has been applied. These strips help to maintain the seal over the wear time of the dressing. In awkward areas, it may be useful to apply the strips to help achieve a seal prior to turning on the pump. Place each strip so that it overlaps the dressing border by approximately 1cm (2/5 inch) as shown in Figure 6. Ensure that the tubing is not twisted or trapped between clothing. With some systems, if the fixation strips are removed at any time, the dressing should also be replaced. Figure 6 – Application of Dressing Fixation Strips Dressing Changes 1. Dressings used with single-use NPWT systems should be changed according to standard wound management guidelines, typically every 3 to 4 days. More frequent dressing changes may be required depending on the level of exudate, the condition of the dressing, wound type/size, orientation of the dressing, environmental considerations, or other patient considerations (e.g., when used on infected wounds). At the health care professional’s discretion, the dressing may be left in place for up to 7 days. 2. Dressings should be inspected regularly. If the dressing appears ready for changing, it should be disconnected from the pump. The fixation strips should be stretched away from the skin and the dressing lifted at one corner and peeled back until it has been fully removed. Apply another dressing according to the manufacturer’s instructions, connect it to the pump, and the press the appropriate button to reinitiate the therapy. 3. Based on dressing change frequency, a new single-use NPWT system kit will be required depending upon whichever of the following occurs first: either when both dressings have been used or after 7 days when the pump automatically stops functioning as indicated by the device. 28 4. The dressing should be disposed of as clinical waste. The batteries should be removed from the pump; and both batteries and pump disposed of according to local regulations. Use with Fillers and Wound Contact Layers Some single use NPWT systems are compatible with standard gauze and foam fillers used in traditional NPWT where this is clinically appropriate, e.g., on a depressed wound defect where the dressing does not conform to the surface. When a filler is used, the filler and the system dressing should be changed 2 to 3 times a week, according to local clinical protocol and the manufacturer’s instructions. The gauze should loosely fill to the surface of the wound; the wound should not be over packed with gauze. A single use NPWT system may be used over the top of a nonadherent layer if required, e.g., over a skin graft. On infected wounds or wounds at risk of infection, silver-coated antimicrobial dressings may be used under the system. A sample of NPWT recommended guidelines based on wound type is provided in Table 4.61,62 29 Table 4. Recommended Guidelines Wound Type Suggested Filler Rationale for Use Cycles Target Pressure Special Considerations Acute/ traumatic wound Gauze or foam Edema removal, wound contraction, granulation growth, protection from outside contaminants Continuous for first 48 hours, intermittent for duration of therapy -80 to -120 mm Hg Protect infected wounds and fragile structures. Avoid desiccation of tendon if exposed Surgical wound dehiscence Foam Edema removal, wound contraction, granulation growth, protection from outside contaminants Continuous for first 48 hours, intermittent for duration of therapy -80 to -120 mm Hg Debride any devitalized tissue prior to start of NPWT Meshed graft/ bioengineered tissue Gauze Edema removal, granulation tissue growth, adherence of flap Continuous for duration of therapy -50 to -80 mm Hg Dressings are typically removed after 5 days Pressure ulcer Gauze Granulation tissue growth, removal of edema, wound contraction, moist healing environment, protection from outside contaminates. Continuous for duration of therapy -60 to -80 mm Hg Address underlying etiology and related healing factors – debride sloughing or necrotic tissue prior to start of NPWT or use foam Chronic ulcer (diabetic/ arterial vascular) Gauze or foam Edema removal, granulation tissue growth, adherence of flap Continuous for duration of therapy -60 to -80 mm Hg Sharp debridement of devitalized tissue prior to placement of NPWT Flaps Gauze Surgical/wound drainage removal underneath sutures, promotes flap adherence to wound base, helps immobilize flap, protects from contaminants Continuous for duration of therapy -50 to -80 mm Hg Dressings are typically removed after 5 days Partial thickness abdominal (muscle intact) Foam Edema removal, granulation tissue growth, adherence of flap Continuous for duration of therapy -80 to -120 mm Hg Layer filler into the wound from the bottom up to ensure it fits the cavity and has contact with the wound margins Wound tunneling Foam or moist gauze Wound retraction, stimulation of granulation tissue formation, continuous removal of exudates, reduction of interstitial edema Continuous or intermittent based on wound characteristics and physician orders Based on wound characteristics and physician orders Avoid packing too tightly or placing friction on the wound edges. Change dressings every 48 hours for the first several days; when drainage decreases, change dressings every 72 hours. Keep wound and tunnels clean using soft-tipped irrigation cannulas. Appropriate antimicrobial therapy as needed if infection is suspected. 30 NPWT: Evidence-Based Patient Outcomes NPWT Research As previously noted, over the past 15 years, NPWT has provided clinicians with a powerful new resource to manage complex wounds. And, unlike many other wound care treatments and dressings, NPWT has a relatively good evidence base to demonstrate its effectiveness.63 The benefits of NPWT as documented in the literature are outlined below. • An early series of basic animal studies conducted by Morykwas, et al, using a negative pressure technique (i.e., vacuum-assisted closure) to expedite wound healing demonstrated that blood flow levels increased fourfold when 125 mm Hg subatmospheric pressure was applied; significantly increased rates of granulation tissue formation occurred with both continuous (63.3 ± 26.1%) and intermittent (103% ± 35.3%) application.64 In addition, tissue bacterial counts were significantly reduced after 4 days of application and random-pattern flap survival significantly increased by 21% in comparison to controls. The authors determined that the application of controlled negative pressure creates a closed, moist environment that promotes wound healing. • In a recent report, Erba, et al investigated how VAC affects wound hypoxia and related profiles of angiogenic factors and to identify the anatomical characteristics of the resultant, newly formed vessels.65 Their results demonstrated that VAC-treated wounds were characterized by the formation of elongated vessels, aligned in parallel and consistent with physiological function, in comparison to wounds treated with occlusive dressings (i.e., the control wound) that showed formation of tortuous, disoriented vessels. Moreover, VAC-treated wounds displayed a well-oxygenated wound bed, with hypoxia limited to the direct proximity of the VAC-foam interface, where higher vascular endothelial growth factor levels were found. In contrast, occlusive dressing control wounds showed generalized hypoxia, with associated accumulation of related angiogenic factors. The combination of established gradients of hypoxia and vascular endothelial growth factor expression along with mechanical forces exerted by VAC therapy was associated with the formation of more physiological blood vessels compared to occlusive dressing control wounds. These morphological changes are likely a necessary condition for improved wound healing. • Kamolz, et al demonstrated that patients with a partial thickness or mixed thickness burn may benefit from the application of negative pressure therapy through a reduction in tissue edema formation and an increase in tissue perfusion.66 • Sabena, et al demonstrated that the application of micromechanical forces (i.e., mechanical stimulation of the wound bed) may be a useful method with which to stimulate wound healing through promotion of cell division, angiogenesis, and local elaboration of growth factors.67 • In an animal study conducted by Wackenfors, et al, laser Doppler was used to measure microvascular blood flow to an inguinal wound during NPWT therapy (-50 mm Hg to -200 mm Hg), including consideration of the different tissue types and the distance from the wound edge.68 NPWT was shown to induce an increase in 31 microvascular blood flow a few centimeters from the wound edge. The increase in blood flow occurred closer to the wound edge in muscular as compared to subcutaneous tissue (1.5 cm and 3 cm, at -75 mm Hg). In the immediate proximity to the wound edge, blood flow was decreased; this hypoperfused zone was increased with decreasing pressure and was especially prominent in subcutaneous in comparison to muscular tissue. When NPWT was discontinued, blood flow increased multifold, which may be due to reactive hyperemia. The authors concluded that NPWT therapy affects microvascular blood flow to the wound edge and therefore may promote wound healing. A low negative pressure during treatment may be beneficial, especially in soft tissue, to minimize the potential ischemic effects; intermittent NPWT may further increase blood flow. • More recently, Borquist, et al further clarified the effects of NPWT (at -20, -40, -80, and -125 mm Hg) applied to a peripheral porcine wound on periwound blood flow using thermodiffusion, trancutaneous, and invasive laser Doppler velocimetry to measure the blood perfusion 0.5, 1.0, and 2.5 cm from the wound edge.69 The results of this study showed that during NPWT, both increases and decreases in blood flow can be seen in the periwound tissue, depending on the distance from the wound edge and the pressure level. The pattern of response depends partly on the measurement technique used; however, the combination of hypoperfusion and hyperperfusion caused by NPWT may accelerate wound healing. • Armstrong and Lavery, investigating whether NPWT improves the proportion and rate of wound healing after partial foot amputation in diabetic patients, reported that in the group treated with NPWT, more patients healed; the rate of wound healing, based on the time to complete closure, was faster; and the rate of granulation tissue formation, based on the time to 76% -100% formation in the wound bed, was faster than for patients in the control group.70 The authors concluded that NPWT appears to be a safe and effective treatment for complex diabetic foot wounds, and could lead to a higher proportion of healed wounds, faster healing rates, and potentially fewer re-amputations than standard care regimens. • Apelgvist, et al evaluated resource utilization and direct economic costs of care in 162 diabetic patients with post amputation wounds who were treated with NPWT or standard moist wound therapy (MWT).71 The results of this study demonstrated that treatment of this patient population using NPWT resulted in lower resource utilization and a greater proportion of patients who obtained wound healing at a lower overall cost of care in comparison to the use of MWT. • A study of 342 patients conducted by Blume, et al also demonstrated that NPWT was safe and more efficacious than advanced moist wound therapy for the treatment of diabetic foot ulcers.72 • Atkins, et al noted that sternal wound infection (SWI) remains a devastating complication after cardiac surgery and decreases long-term and short-term survival; in treating documented SWI, NPWT reduces wound edema and time to definitive closure and improves peristernal blood flow after internal mammary artery harvesting.73 The authors evaluated NPWT as a form of “well wound” therapy in patients at substantial risk for SWIs, based on existing risk stratification models in 32 a review of 57 adult cardiac surgery patients. After preoperative risk assessment, NPWT was instituted on the clean, closed sternotomy immediately after surgery and continued 4 days postoperatively. Adverse postoperative events, including SWI, need for readmission, and other complications, were documented. The results of this review demonstrate that, in this high risk group, 3 postoperative SWI cases were anticipated but may have been mitigated by NPWT. Furthermore, NPWT is an easily applied and well-tolerated therapy and may also stimulate more effective wound healing. Therefore, among patients with increased SWI risk, strong consideration should be given to NPWT as a form of “well wound” therapy. • Reddix, et al studied the effects of incisional vacuum-assisted closure (IVAC) on wound complications (e.g., dehiscences, infections) associated with surgical treatment of acetabular fractures in morbidly obese patients (i.e., those with a body mass index, >40 kg/m2).74 The results showed that, over 5 years of IVAC use in 19 consecutive patients, no wound complications were found. Based on these results, the authors concluded that IVAC is an attractive treatment adjunct to minimize postoperative wound complications in this patient population. • Greene, et al demonstrated that wounds subjected to NPWT had greater microvessel density, as compared with the same wound prior to treatment; therefore, NPWT provides a favorable wound-healing environment by stimulating angiogenesis.75 • NPWT has also been shown to assist in the physical splinting of grafts. Llanos, et al evaluated the effectiveness of a negative pressure closure (NPC) technique in the integration of split-thickness skin grafts (STSG) to the recipient site.76 The median loss of the STSG in the NPC group was 0.0 cm versus 4.5 cm in the control group; the average length of hospital stay was of 13.5 days in the NPC group versus 17 days in the control group. The authors concluded that the use of NPC significantly diminishes the loss of STSG area and decreases the length of hospital stay; based on these results, it should be routinely used for these types of procedures. • A recent prospective, noncomparative, multicenter evaluation was conducted to quantitatively assess the clinical efficacy of gauze-based NPWT as an adjunctive therapy to STSG procedures.77 In this study, 21 patients had NPWT applied prior to definitive closure by STSG or flap techniques (the pregraft group); another group of 21 patients underwent an STSG procedure and had gauze-based NPWT placed immediately on top of the STSG (the postgraft group). Negative pressure was applied at -80 mm Hg. In the pregraft group, NPWT was used for an average of 12 days. Improvement in quality of wound bed with decreased nonviable tissue (from 20% to 0% median wound area) and increased granulation tissue (from 20% to 90% median wound area) were observed. In the postgraft group, the average duration of therapy was 5 days, at which point the median percentage skin grafttake was 96%. Based on these results, the authors concluded that gauze-based NPWT appears to be an effective addition to the care and management of wounds intended for definitive closure by STSG. • Gomoll, et al, demonstrated that the application of a NPWT closure sponge as a postoperative dressing provides a clean, dry wound environment in the immediate 33 postoperative period to reduce postoperative swelling and prolonged drainage, thereby reducing the need for dressing changes and potentially higher rates of SSI.78 • Mouës, et al examined whether the positive effect on wound healing found in vacuum-assisted closure-treated wounds could be explained by an effect on the bacterial load in 54 patients needing open wound management prior to surgical closure.79 Wounds were randomized to either vacuum-assisted closure therapy (29 patients) or treatment by conventional moist gauze therapy (25 patients). Healing was characterized by development of a clean granulating wound bed (i.e., “ready for surgical therapy”) and reduction of wound surface area; to quantify bacterial load, biopsies were collected. The results demonstrated no significant difference in the time needed to reach “ready for surgical therapy” with both therapies. Wound surface area reduction was significantly better in vacuum-assisted closure-treated wounds: 3.8 ± 0.5 percent per day compared to conventionally-treated wounds, 1.7 ± 0.6 percent per day. The total quantitative bacterial load was generally stable in both therapies. However, nonfermentative gram negative bacilli showed a significant decrease in vacuum-assisted closuretreated wounds, whereas Staphylococcus aureus showed a significant increase in vacuum-assisted closure-treated wounds. The authors concluded that the results of this study shows a positive effect of vacuum-assisted closure therapy on wound healing, expressed as a significant reduction of wound surface area; however, this could not be explained by a significant quantitative reduction of the bacterial load. • Malmsjö, et al conducted an experimental animal study to determine the early effects of NPWT on pressure transduction and wound contraction in wounds filled with either polyurethane foam or gauze.80 The results of this study demonstrated that for both gauze and foam fillers, wound bed negative pressure increased linearly with delivered vacuum with little deviation from set pressure; similar tissue contraction was observed when using foam and gauze. The most prominent contraction was observed in the range of 0 to -50 mm Hg, with greater vacuum producing only minor further movement of the wound edge. • Dunn, et al conducted a prospective, multi-center, non-comparative clinical investigation using gauze-based NPWT in chronic and acute wounds in 131 patients.81 Traumatic, post-surgical and chronic wounds were assessed measuring wound area, depth, and volume. The percentage of weekly reductions observed were 8.3 per cent in wound area, 15.8 per cent in wound depth, and 20.5 per cent in wound volume. Other observations included: reduction in exudate level from baseline to treatment discontinuation (p.001); increase in red granulation tissue (p=0.007); and decrease in non-viable tissue (p<0.001). The authors concluded gauze-based NPWT can be used to address reduction in wound volume, management of exudates, and improvement in wound bed quality. • NPWT has also been shown to decrease pain and increase comfort during dressing changes. 34 ◦◦ Fujioka, et al described a case of a child with a severe leg degloving injury who underwent successful NPWT with reduced pain.82 An 8-year-girl with lower extremity avulsion injuries underwent debridement and received NPWT for 17 days, during which the dressing foam was changed only twice; secondary skin grafting was performed 24 days later, and the wound was resurfaced 35 days after injury. The authors concluded that NPWT reduces the frequency of required dressing changes, even while the wound is releasing massive exudate, which reduces pain and therefore brings comfort to injured children. ◦◦ Hurd, et al conducted a prospective, multi-center, non-comparative clinical investigation using gauze-based NPWT in chronic and acute wounds of over 152 patients.83 The average duration of therapy was 18 days, with 91% of the patients progressing towards healing at the end of therapy. The results demonstrated that wound pain and odor were significantly reduced over the course of NPWT. Wound pain during dressing changes was reported to be absent in 80% of dressing removals. No damage to the wound bed following dressing removal was observed in 96% of dressing changes. Dressing applications were considered easy in 79% of the assessments and took an average of 20 minutes to complete. ◦◦ Fraccalvieri, et al compared the level of pain and feedback in post-traumatic patients before, during NPWT treatment, and at the dressing change after treatment with NPWT with two different fillers (gauze [13 patients] and foam [19 patients]).84 The patients were asked to respond to a questionnaire conducted by the same physician to assess the level of pain using a verbal numerical scale. There were no significant differences in pain before and during the treatment with NPWT with either gauze or foam. In regard to pain during dressing change, the average scores for the foam was 6.5, while for the gauze, it was 4.15; this is a statistically significant difference between these two groups. The findings of this study confirmed that patients experienced less pain at the dressing change after treatment with gauzebased NPWT. In the authors’ opinion, this finding is related to the more adhesive property of the foam probably because of the ingrowth of the granulation tissue in the micropores present on the foam. ◦◦ A study by Braakenburg, et al also demonstrated that the use of vacuumassisted closure therapy in all types of wounds resulted in healing that is at least as fast as with modern wound dressings; cardiovascular and diabetic patients in particular benefit from this therapy.85 In addition, while the total costs of vacuum-assisted closure are comparable to those of modern wound dressings, the advantage is its comfort for patients and nursing staff. These studies reflect evidence that NPWT is efficient in treating acute and chronic wounds with improved clinical outcomes and have stimulated health care systems around the world to provide NPWT services. In addition, these studies motivated both national and international committees to develop NPWT guidelines in wound care. This year more than 250 world thought leaders from 27 countries met in Berlin, Germany to examine 35 NPWT’s potential to reduce the human and economic costs of wounds. This meeting was the fourth in a series of conferences to serve as a forum for professionals to share their knowledge of NPWT and begin a collaborative process for developing consensus guidelines on the use of NPWT therapy. Research on Single-use NPWT Systems Research has also been conducted on single-use NPWT systems. At the University of Lund in Sweden, scientists examined whether this type of system delivers NPWT in the same manner as traditional NPWT devices. In making such an assessment, the researchers tested three factors which have been established as mechanisms of action for NPWT, as previously noted: • The transmission of negative pressure to the base of the wound.86 • Tissue contraction.87 • Establishing a characteristic pattern of periwound blood flow.88,89 These tests were undertaken in wounds on anesthetized pigs. Pressure was measured through probes inserted in the base of the wound; laser Doppler filaments were then used to measure blood flow. In order to demonstrate that a single use, disposable NPWT pump and corresponding dressing operate as conventional NPWT devices, combinations of this type of pump with or without different fillers and a traditional pump (set at -80mmHg) with or without different fillers, were tested alongside the single use NPWT pump and dressing. In the single use pump, the negative pressure of -80 mm Hg was selected, since research has shown that both foam and gauze fillers can operate successfully at this pressure and clinical and physiological effects are near maximal.90,91 The results of these studies are discussed below. • Transmission of negative pressure levels at the wound bed. In each test combination, the pressure levels achieved at the wound bed were virtually identical to the operating set point of the single use NPWT pump. A single use NPWT pump and dressing were shown to operate to deliver specified negative pressure to the wound bed with or without foam and gauze fillers. • Tissue contraction. In the defect wound, tissue contraction was observed for all pump and dressing combinations, including the single use pump and dressing combination. Slightly greater contraction (92%) was seen with negative pressure applied to foam fillers than with gauze filler (90%) or the single use pump and dressing (92%). This study verifies that a single used NPWT delivers tissue contraction comparable with conventional NPWT devices operating on defect wounds. • Establishing a characteristic pattern of periwound blood flow. It has been established that with either foam or gauze-based conventional NPWT, a characteristic pattern of blood flow is set up after negative pressure is applied to a defect wound. Close (0.5 cm) to the wound bed or wound edge, blood flow is reduced; further away (2.5 cm) from the wound bed or wound edge, blood flow is stimulated.92,93,94 Combinations of traditional and single use NPWT pumps were 36 used with gauze, foam or single use dressings on 6 cm diameter full thickness wounds. Close to the wound edge (i.e., 0.5 cm) the single use pump and dressing caused a reduction in blood flow as did all other combinations of NPWT pump and dressing. In contrast, further away from the wound edge (2.5 cm), the single use pump and dressing caused a stimulation in blood flow as did all other combinations of NPWT pump and dressing. The single use pump and dressing operated in an identical fashion to conventional NPWT devices in setting up the same patterns of blood flow.95,96 A recent prospective, non-comparative, multicenter clinical trial assessed the functionality and clinical acceptance of a single-use NPWT system.97 In this study, 20 patients were recruited for a maximum treatment period of 14 days; 16 (80%) patients had closed surgical wounds, two (10%) patients had traumatic wounds, and two (10%) patients received meshed split thickness skin grafts. The NPWT devices were fitted with data log chips to enable longitudinal assessment of negative pressure and leak rates during therapy. The average study duration was 10.7 days (range: 5 to 14 days) and the mean dressing wear time per individual was 4.6 days (range 2 to 11 days). Fifty-five percent of wounds had closed by the end individual patient was 4.6 days (range: 2 to 11 days). Fifty-five percent of wounds had closed by the of the 14-day study or earlier, with a further 40% of wounds progressing to closure. Real-time pressure monitoring showed continuous delivery of NPWT. Clinical studies of the disposable NPWT system confirmed the ability of a simplified single-use device to function consistently over the expected wear time. Furthermore, the anticipated reduced costs, ease of use, and increased mobility of patients using this system may enable NPWT benefits to be available to a greater proportion of patients. The following case studies also demonstrate the effectiveness of single-use NPWT systems in improving patient outcomes with various types of wounds. • Case Study #1: Traumatic Wound. A 30-year-old woman was treated for a dog bite injury on her lower leg; following surgery, her wound measured 7.5 cm x 6 cm and was partially closed. The patient was given a single-use NPWT system with a 15 cm x 20 cm dressing, which the surgeon was able to apply quickly, in about five minutes. The patient had the system in place at home for ten days; the pump was changed on the sixth day. On day ten, analgesics were discontinued and upon routine dressing change, it was noted that the wound was progressing. On day fourteen, the treatment ended according to the set protocol, with the wound still progressing well. The patient was given an absorbent dressing in order to conclude her treatment. The clinician commented on the portability and ease of application of this type of system for the patient, who was treated at home. This patient’s wound healing process is depicted in Figure 7. 37 Figure 7 – Case Study #1: Traumatic Wound Treated with Single-use NPWT System Single-use NPWT system was applied 4 days after initial suturing due to skin flap necrosis around the edge of the wound Postoperative day #1: Dressing in place Postoperative day #14 showing vascularization through the scar • Case Study #2: Skin Graft Post-Burn. An 80-year-old man was treated for a nonhealing burn on the knee with debridement and a skin graft. The wound measured 15 cm x 5 cm with moderate levels of exudate. Methicillin-resistant Staphylococcus aureus (MRSA) had been detected on a wound swab; the patient was prescribed systemic antibiotics. A single- use NPWT system with a 10 cm x 25cm dressing was applied to stabilize the skin graft and absorb the wound exudate. A low adherent wound contact layer was applied between the graft and the dressing. The patient was discharged from the hospital on day two with a single-use NPWT system in place. On day three, there was no vacuum per the leak indicator mechanism, but the problem resolved itself. Treatment with this system continued until day five, when on assessment, the skin graft had taken and treatment progressed to an antimicrobial, silver coated barrier dressing and a conventional dressing. Figure 8 illustrates this patient’s wound healing process. Figure 8 – Case Study #2: Skin Graft Post-Burn Treated with Single-use NPWT System Non-healing burn wound before debridement and application of skin graft Single- use NPWT dressing in place over the skin graft Day #5: Skin graft after removal of dressing • Case Study #3: Post-Surgical Wound: Hip Implant. A 52-year-old woman with osteoarthritis underwent reconstructive hip surgery. Her wound measured 15.5 cm x 0.2 cm and was closed with a suture and thin adhesive strips. A single-use NPWT system was applied by the surgeon and assistant in the OR using a 10 cm x 25 cm 38 dressing. Treatment continued uneventfully for six days, throughout which the patient was comfortable. At the routine dressing change on day seven, the wound was seen to be progressing to closure with healthy surrounding tissue and no signs of infection. A new dressing was applied by the nurse. At the next routine dressing change on day ten, the wound was observed to be closed. The clinician estimated that the wound had closed three days earlier than might have been expected with an advanced wound care dressing. The wound healing process for this patient is shown in Figure 9. Figure 9 – Case Study #3: Post-Surgical Hip Implant Wound Treated with Single-use NPWT System Wound immediately following hip implant NPWT Postoperative day #2: Single- use dressing in place Postoperative day #10: Wound closed after dressing removal Cost Effectiveness Both the direct and indirect costs associated with care of acute and chronic wounds contribute to overall national health care expenditures. As noted above, NPWT is used to treat acute wounds (e.g., surgical and traumatic wounds; burns); it is also used in the treatment of chronic wounds, i.e., diabetic foot ulcers, pressure ulcers, and vascular ulcers (including venous ulcers and arterial ulcers).98 These additional costs of care for the treatment of SSIs and chronic wounds that do not heal properly are significant and expected to continue to rise; in addition, hospitals and health care facilities are no longer reimbursed for these costs. For these reasons, health care professionals should implement appropriate, evidencebased strategies to promote effective wound healing to eliminate these additional costs. The implementation of NPWT earlier in wound management (rather than later during wound therapy) can offset costs associated with lengthy therapy and sequelae.99 Several research studies have demonstrated cost savings with NPWT in comparison to traditional wound dressings, as outlined below. • In a recent study, Rahmanian-Schwarz et al evaluated both the clinical and cost effectiveness of two NPWT systems.100 A total of 42 patients with an acute or chronic wound were randomly assigned to treatment with either a traditional NPWT system or with an alternative, newly available polyurethane foam-based NPWT system; NPWT was applied after surgical debridement to prepare the wound bed for skin grafting in both groups of patients. After skin grafting, NPWT was applied additionally to secure skin grafts and improve graft survival. Primary outcome measures were the time to complete healing (in days) and duration of the NPWT application (in days); secondary outcome measures were the number of dressing changes and reported complications. 39 In addition, the cost-benefit in the clinical implementation was evaluated. The results of this study showed that there were no significant differences in the two outcome measures between the two groups; no complications occurred in either group. However, at the author’s facility, a supply agreement with the product provider made the new polyurethane foam-based NPWT system appear to be more cost-effective. • Bondokji, et al evaluated the clinical efficacy of a polyurethane foam-based NPWT system in the treatment of 18 patients who had various types of wounds including pressure ulcers, diabetic foot ulcers, traumatic and surgical wounds.101 The duration of treatment was 14.6 days (range of 5 to 29 days). At the completion of therapy, 83% (15) of wounds had progressed sufficiently, leading to a change in treatment of NPWT. Average reductions in wound area, depth and volume of 31.3%, 45.5%, and 74.2% respectively were observed over the course of therapy. Exudate level and wound malodor were significantly reduced between the onset and the end of NPWT. The percentage cover of red granulation tissue in the wound bed was significantly increased and non-viable tissue significantly reduced between the onset and the end of NPWT. The authors concluded that these data demonstrate that an alternative foam-based NPWT system is able to address the common treatment goals associated with application of NPWT, including reduction in wound dimensions, decrease in exudate levels, and an improvement in wound bed quality. • Dowsett, et al monitored NPWT use over a 2-year period in three community sites.102 The data analysis showed that the average cost of dressing complex wounds with NPWT would be significantly less than with the use of traditional dressings, because the increase in nursing visits could increase costs. Therefore, more negative pressure should be used and initiated in the community, based not only on the improved quality of life for patients, but also on the economic benefits of this therapy. • Othman reported on the use of NPWT in chronic wound management and the assessment of the evidence behind it, its cost effectiveness, and the outcome it has on patients’ satisfaction and life style.103 After a review of multiple studies, the author concluded that NPWT can be a useful source of reducing the costs associated with chronic wound management and saving money by its effect on expediting wound healing; however, its use must be considered according to specific case needs. • de Leon, et al evaluated the cost-effectiveness of NPWT in patients with complex wounds in a long-term acute care (LTAC) setting.104 A retrospective chart review was conducted to determine the average daily wound volume reduction, average daily wound area reduction, and average cost per cubic centimeter of wound volume reduction for patients treated with NPWT in comparison to those treated with topical advanced moist wound-healing strategies (i.e., non-NPWT). The results demonstrated that the patients treated with NPWT showed a statistically significantly higher average daily rate of volume reduction as compared with the advanced moist wound-healing group (5.02 ± 13.36 versus 0.40 ±0.88 cm3/ 40 day). The cost per cubic centimeter reduction was $11.90/cm3 in the NPWT group versus $30.92/cm3 in the moist wound-healing group. The authors concluded that postsurgical LTAC patients who were treated with NPWT had a more accelerated rate of wound closure, compared with patients treated with advanced moist wound-healing therapy; these results suggest that, for this patient group, NPWT may be more clinically effective in reducing wound volume, compared with advanced moist wound healing. Furthermore, the lower cost per cubic centimeter volume reduction suggests that NPWT produces a more favorable cost-effective solution. Therefore, when developing a wound-healing strategy, it is important to base cost decisions on overall cost and not individual product cost when implementing advanced technology as part of the overall treatment plan. • Vuerstaek, et al evaluated the efficacy of vacuum-assisted closure in the treatment of chronic leg ulcers in a randomized controlled trial in which 60 hospitalized patients with chronic leg ulcers were randomly assigned to either treatment by NPWT or therapy with conventional wound care techniques (i.e., the control group).105 The primary outcome measure was the time (i.e., days) to complete healing. The results demonstrated that the median time to complete healing was 29 days in the NPWT group compared with 45 days in the control group. Additionally, wound bed preparation during NPWT was also significantly shorter (7 days) than during conventional wound care (17 days). The costs of conventional wound care were higher than those of NPWT. Both groups showed a significant increase in quality of life at the conclusion of therapy and a significant decrease in pain scores at the end of follow-up. These authors concluded that NPWT should be considered as the treatment of choice for chronic leg ulcers based on its significant advantages in the time to complete healing and wound bed preparation time in comparison to conventional wound care; NPWT therapy appears to be superior to conventional wound care techniques, especially during the preparation stage. Coding and Reimbursement General Considerations106,107 The appropriate forms must be completed by the clinician and signed by the physician or practitioner and submitted to the insurance carrier or Medicare provider, with the NPWT Healthcare Common Procedure Coding System (HCPCS) code identified. The HCPCS Level II coding system is a comprehensive, standardized system that classifies similar products that are medical in nature into categories for the purpose of efficient claims processing. Products are classified based on similarities in function and if the products demonstrate significant therapeutic distinctions from other products. Currently, all NPWT devices are classified into the same HCPCS codes (see Table 5). In addition, all NPWT equipment must be non-investigational, i.e., it must be approved by the United States FDA for use as a NPWT device. 41 Table 5 – HCPCS Codes for NPWT Equipment and Supplies108 Equipment: E2402 Negative pressure wound therapy electrical pump, stationary or portable Supplies: Wound care set, for negative pressure wound therapy electrical pump, includes all supplies and accessories A6550 A7000 Canister, disposable, used with suction pump, each G-Codes Effective January 1, 2013, Medicare has created two new HCPCS codes to provide a mechanism for payment of NPWT using a disposable device that is not durable medical equipment (DME), as outlined below and detailed in Table 6:109 • G0456: Negative pressure wound therapy, (e.g., vacuum assisted drainage collection) using a mechanically-powered device, not DME, including provision of cartridge and dressing(s), topical application(s), wound assessment, and instructions for ongoing care, per session; total wound(s) surface area less than or equal to 50 square centimeters. • G0457: Negative pressure wound therapy, (e.g., vacuum assisted drainage collection) using a mechanically-powered device, not DME, including provision of cartridge and dressing(s), topical application(s), wound assessment, and instructions for ongoing care, per session; total wound(s) surface area greater than 50 square centimeters. The new G-codes are not product specific; the intent is to provide codes for use when physicians or other practitioners are applying a surgical dressing using any disposable NPWT device. Therefore, providers may appropriately use these codes when submitting claims for negative pressure wound therapy using any disposable NPWT product, as long the service is medically necessary and meets all other criteria for coverage. The new codes are also intended to include the supplies and the service of applying a surgical dressing using a disposable NPWT device. In the hospital outpatient department (HOPD), qualified therapists typically provide services under a certified therapy plan of care to Medicare beneficiaries; these are called “always therapy” services. When services are performed by an individual outside of a certified therapy plan of care, these are referred to as “sometimes therapy” services. Under Medicare’s Outpatient Prospective Payment System (OPPS), separate reimbursement is given to services designated as “sometimes therapy.” HCPCS codes G0456 and G0457 are designated by Medicare as “sometimes therapy” codes. The complete list of services under each designation is maintained by Medicare. For a qualified therapist’s claims to be paid for “sometimes therapy” under the Medicare Physician Fee Schedule (MPFS), the provider must append the –GP modifier (physical therapy) to the G-code and report the charges under and appropriate therapy revenue code (e.g., 042x, 043x, or 044x). In contrast, for a facility to be paid for a “sometimes 42 therapy” code under the OPPS (see Table 6), the hospital should not append the –GP modifier to the G-code, nor should it report the therapy revenue codes. Because many disposable NPWT devices are used in the home, some commercial carriers may choose to cover these systems as a miscellaneous supply under their DME benefit. In that case, they may request that the miscellaneous supply code (A4649) or the miscellaneous DME code (E1399) be submitted. Both of these codes are not assigned a value; therefore, the claim will be manually processed and will require the submission of further information to the carrier. If the disposable NPWT device is deemed to be noncovered, it should be reported under the supply code A9270 (i.e., non-covered item or service). Final determination of coverage and payment will be at the carrier’s discretion. 43 Table 6 – G-Codes: Site of Service Site of Service Hospital Inpatient Setting (POS 21) Code Medicare and Commercial Payers: Report under an appropriate therapy revenue code (e.g., 042x, 043x, or 044x) Payment Medicare: No separate reimbursement – payment is included in the hospital’s Medicare Severity Diagnosis Related Groups (MS-DRG). Commercial Payers: Contract specific Physician Office Setting (POS 11) Medicare: Billed by physician for each treatment performed Includes: Service + Supplies (Application of a dressing using a disposable NPWT device) Medicare: Each physician claim is individually priced by the carrier Commercial Payers: Contract specific Commercial Payers: Have historically followed Medicare’s direction to reserve the use of CPT codes 97605 and 97606 for NPWT services using canister systems versus disposable systems. Individual carriers should be contacted for guidance on the appropriate codes to report the disposable NPWT service. Hospital Outpatient Setting (POS 22) Medicare Conditions of Coverage “Sometimes Therapy:” COVERED • Qualified therapist • Provided outside of a Certified Therapy Plan of Care Professional Claim Coding: G0456-GP (append physical therapy modifier). Report under an appropriate therapy revenue code (042x, 043x, or 044x) Medicare (Sometimes Therapy): 2013 National Average = $209.65 (APC 0016) Commercial Payers: Contract Specific HOPD Claim: No –GP modifier or therapy revenue code. Home Setting (POS 21) DEVICE ONLY DEVICE ONLY Medicare: A9270 – Non-covered item or service. Medicare: Not covered/paid Commercial Payers: Carrier specific. Commercial Payers: If covered as DME, individually reviewed and priced Options include: • A9270 – Non-covered item or service • A4649 – Surgical supply, miscellaneous • E1399 – Durable medical equipment, miscellaneous 44 Coverage Determination110 A. An NPWT pump and related supplies are covered when the criteria outlined below for wounds in a home or inpatient setting (sections A and B, respectively) are met: Ulcers and Wounds in the Home Setting: The patient has a chronic Stage III or IV pressure ulcer, neuropathic (e.g., diabetic) ulcer, venous or arterial insufficiency ulcer, or a chronic (defined as being present for at least 30 days) ulcer of mixed etiology. A complete wound therapy program, as applicable based on the type of wound, should have been tried or considered and ruled out before application of NPWT. For all ulcers or wounds, the following components of a wound therapy program must include a minimum of all of the following general measures, which should either be addressed, applied, or considered and ruled out prior to application of NPWT: ◦◦ Documentation in the patient’s medical record of evaluation, care, and wound measurements by a licensed medical professional; ◦◦ Application of dressings to maintain a moist wound environment; ◦◦ Debridement of necrotic tissue if present; and ◦◦ Evaluation of and provision for adequate nutritional status For Stage III or IV pressure ulcers: ◦◦ The patient has been appropriately turned and positioned; ◦◦ The patient has used a group 2 or 3 support surface for pressure ulcers on the posterior trunk or pelvis; and ◦◦ The patient’s moisture and incontinence have been managed appropriately. For neuropathic (i.e., diabetic) ulcers: ◦◦ The patient has been on a comprehensive diabetic management program; and ◦◦ Reduction in pressure on a foot ulcer has been accomplished with appropriate modalities. For venous insufficiency ulcers: ◦◦ Compression bandages and/or garments have been consistently applied; and ◦◦ Leg elevation and ambulation have been encouraged. B. Ulcers and Wounds Encountered in an Inpatient Setting: An ulcer or wound (as described above) is encountered in the inpatient setting and, after wound treatments described have been tried or considered and ruled out, NPWT is initiated because it is considered in the judgment of the treating physician to be the best available treatment option. 45 The patient has complications of a surgically created wound (e.g., dehiscence) or a traumatic wound (e.g., preoperative flap or graft) where there is documentation of the medical necessity for accelerated formation of granulation tissue that cannot be achieved by other available topical wound treatments (i.e., other conditions of the patient will not allow for healing times achievable with other topical wound treatments). In either of the above scenarios, NPWT will be covered when treatment continuation is ordered after discharge to the home setting. If criterion A or B above is not met, the NPWT pump and supplies will be denied as not reasonable or necessary. In addition, a NPWT pump and supplies will be denied at any time as not reasonable or necessary if one or more of the following are present: ◦◦ The presence in the wound of necrotic tissue with eschar, if debridement is not attempted; ◦◦ Untreated osteomyelitis within the vicinity of the wound; ◦◦ Cancer present in the wound; ◦◦ The presence of an open fistula to an organ or body cavity within the vicinity of the wound. C. Continued Coverage. For wounds and ulcers described in sections A or B above, once an NPWT pump and supplies are initiated, in order for coverage to continue, a licensed medical professional must: ◦◦ On a regular basis: ––Directly assess the wound(s) being treated with the NPWT pump, and ––Supervise or directly perform the NPWT dressing changes. ◦◦ On at least a monthly basis, document changes in the ulcer’s dimensions and characteristics. If these criteria are not met, continued coverage of the NPWT pump and supplies will be denied as not reasonable or necessary. D. When Coverage Ends For wounds and ulcers described under sections A or B above, a NPWT pump and supplies will be denied as not reasonable and necessary with any of the following, whichever occurs earliest: ◦◦ The criteria listed under Continued Coverage cease to occur; ◦◦ In the judgment of the treating physician, adequate wound healing has occurred to the extent that NPWT may be discontinued, ◦◦ Any measurable degree of wound healing has failed to occur over the prior month. Wound healing is defined as improvement occurring in either surface area (length x width) or depth of the wound. 46 ◦◦ Four months (including the time NPWT was applied in an inpatient setting prior to discharge to the home) have elapsed using an NPWT pump in the treatment of the most recent wound. ◦◦ Once equipment or supplies are no longer being used for the patient, whether or not by the physician’s order. Coverage for supplies is provided for up to a maximum of 15 dressing kits (A6550) per wound per month, unless there is documentation that the wound size requires more than one dressing kit for each dressing change. Coverage is provided for up to a maximum of 10 canister sets (A7000) per month unless there is documentation showing a large volume of drainage (defined as greater than 90 mL of exudate per day). For high volume exudative wounds, a stationary pump with the largest capacity canister must be used. Suppliers must not dispense a quantity of supplies exceeding the patient’s expected utilization; however, suppliers may dispense a maximum of one month’s supply of dressing kits or canisters at any one time. Discharge111 The patient may be discharged home with the NPWT unit once preauthorization has been established with the patient’s insurance provider; these forms are available through the durable medical equipment’s and manufacturer’s websites. In addition, education should be provided to the home health agency staff and any other caregivers. Single-use NPWT System Compared to Traditional NPWT System Although this activity is focused on single-use NPWT systems, it may be useful to compare some general features of a single-use NPWT system to a traditional NPWT system using one product line on the market illustrated in Table 7. 47 Table 7. Example of features for a single-use NPWT system compared to a traditional NPWT system. Features Single-use NPWT System Traditional NPWT System Suction pressure Continuous negative pressure of nominally 80 mm Hg ± 20 mm Hg Range of pressure 40 mm of Hg to 200 mm of Hg Pressure setting Pre-set at continuous negative pressure of 80 mm Hg No pre-set pressure setting Ability to change pressure Pressure cannot be changed Can set pressure at different levels Intermittent pressure No intermittent pressure settings Intermittent pressure setting features Suction cut-off for full canister Canister-free system. Can manage light to moderate exuding wound up to 400 cm3 (surface area x depth) Audible alarm and light flashes when canister is full. Can manage wound fluid >50 cc/24 hr. Valve control for fluid Filter prevents fluid from flowing backwards toward the patient Filter prevents fluid from flowing backwards toward the patient Battery life Two AA batteries last up to 7 days Varies based on system from 20-40 hrs. Weight /portability of machine <4.2 oz. Pocket sized. Varies from 2.4 lbs for portable use to 7.4 lbs. for IV pole or bed mounting Wound interface New dressing technology manages exudates by absorption and evaporation Foam or gauze dressing Dressing changes Every 3-4 days or may be in place for 7 days at physician’s discretion Every 24-72 hrs Y-connecting ability Cannot be Y-connected Can Y-connect two wounds Handling undermining/ tunneling wounds Needs addition of foam or gauze filler Both foam and gauze dressing kits available for tunneling wounds Use with fistulas Not recommended for high output wounds Dressing kit with irrigation aspiration drain available for fistulas Use with exposed bone or tendon Contraindicated for use with exposed bone or tendon Dressing kit with non adherent gauze or a non-adherent with a foam interface available Handling high bioburden or infected wounds Antimicrobial silver dressing used as a wound contact layer Antimicrobial silver dressing used as a wound contact layer 48 Physician Considerations Effective debridement is needed to help correct abnormalities in acute and chronic wounds and stimulate the healing process. To optimize the healing process with NPWT, it is essential that the clinician ensure the wound bed is assessed and prepared prior to, during, and after therapy. General Treatment Protocol112 • Wound bed preparation is central to the healing process. Removal of tissue that is colonized with substantial bioburden and biofilm is an essential component of continuous wound management. Debridement is an avenue used to essentially “jump start” the wound healing process in a stalled wound, or to remove biofilms. • Dressing changes are generally recommended every 48 to 72 hours or 3 times a week, unless otherwise specified by the physician. • Therapy should be reevaluated if there is no progress in 4 to 6 weeks. • A wound care specialist should measure and assess the wound weekly. • Multiple wounds should be bridged or a Y-connector should be used. Wound Assessment113 The following areas should be addressed at the initiation of NPWT treatment regimen and with every dressing change thereafter. • Wound size: length, width, depth NPWT has the ability to remove interstitial fluid and sloughy necrotic cells/tissue filling a wound causing a slight increase in the volume of the wound initially and within the first few dressing changes if the wound is in the inflammatory phase of wound healing. • Epithelialization: amount and description The fragile new cells should be “silvery” in appearance and supported with gauze or foam in undermined areas to prevent the edges from rolling under. • Necrotic tissue: type and amount Necrotic slough may decrease with NPWT and the autolytic environment established by the transparent film. Eschar should be debrided prior to initiation of NPWT. • Exudate: type, amount and consistency Assess wound exudates for type, amount, color, and consistency for the wound type and anticipated exudates. Significant changes warrant reassessment of the wound. • Odor: present/absent, description Body fluids that have been contained in a sealed system for an extended period of time will likely have an unpleasant odor. This does not necessarily indicate infection but if odor persists following wound cleaning, an assessment for infection may be necessary. 49 • Pain: use facility approved tool for rating pain The patient’s level of pain in relation to the wound itself and/or with dressing changes should also be evaluated. Physician Orders114 Once the physician has carefully assessed the wound and the patient to ensure clinical indications for NPWT are met, the physician orders should include: • Wound location, size, and type • Wound dressing type • Vacuum settings (-40 to -120 mL Hg) • Frequency of dressing changes • Adjunctive dressings Patient/Caregiver Education As noted above, education should be provided to the patient, caregivers, and home health staff members if needed. Education for patients with single-use NPWT pumps should include: • Showering and bathing. Light showering is permissible; however, the pump should be disconnected and placed in a safe location where it will not get wet. The dressing should not be exposed to a direct spray or submerged in water. The tubing attached to the dressing should be facing down so that water does not enter the top of the tube. • Cleaning. Adherence to clinical directives regarding hygiene is of primary importance. The pump may be wiped clean with a damp cloth using soapy water or a weak disinfectant solution. Adverse Reactions Excessive bleeding is a serious risk associated with the application of suction to wounds, which may result in death or serious injury. The wound and dressing should be carefully monitored for any evidence of a change in the blood loss status of the patient. The physician should be notified of any sudden or abrupt changes in the volume or the color of exudate. Troubleshooting115 An NPWT dressing should be assessed for air leaks and resealed as needed. In addition, the seal, connectors, tubing, canister, and pump settings should also be checked. If a problem still persists, troubleshoot as necessary with instructions from the physician or the pump manufacturer’s written instructions. Discontinuation of NPWT NPWT can be discontinued when:116,117 • The wound has met the goals of the physician (e.g., uniformly granulation tissue is achieved; the wound is prepared for grafting; debris is removed); 50 • The wound depth is 0.5cm or less; • The wound does not respond positively within 4 to 6 weeks of therapy; • There is psychological intolerance; and • The patient has an overall medical decline, except when NPWT is used for palliative treatment. Summary Current research demonstrates that NPWT creates a moist wound-healing environment, increases local vascularity and oxygenation of tissues; evacuates exudate, extravasated blood, and bacteria; reduces tissue edema; increases tissue contraction; and mechanically stimulates granulation tissue formation. Negative pressure wound therapy promotes positive outcomes by either accelerating the normal wound healing process or preventing a wound from getting stalled in the inflammatory phase, which is common in diabetic patients. As research on NPWT continues, its mechanisms of action, role, and future potential are becoming clearer; for incision management in high risk patients and some of the most challenging wounds, it is becoming a first line therapy. Unlike many other traditional wound care treatment modalities, NPWT has a relatively good evidence base to demonstrate both its clinical benefits and cost effectiveness, as a result of associated reductions in lengths of hospital stay, healing time, resource utilization, as well as its application in care settings other than the hospital. Today, single-use, disposable NPWT systems that combine all the benefits of NPWT with advanced wound care dressings for use in hospital and community settings represent a significant advancement in wound care technology that facilitates the wound healing process, thereby improving the quality of life for many highrisk patients. 51 Glossary Battery life Wounds that progress through the healing process at a predictable rate from insult to closure; examples are traumatic or surgical wounds. Chronic Wounds Wounds that do not progress through the predictable stages of wound healing or resolve over a reasonable period of time; examples are lower extremity ulcers, diabetic ulcers, and burns. Dehiscence The failure of tissue edges to close after surgical re-approximation. Endogenous Growing from or on the inside; caused by factors within the body or arising from internal structural or functional causes. Exogenous Growing from or on the outside; caused by factors (as food or a traumatic factor) or an agent (as a disease-producing organism) from outside the organism or system; introduced from or produced outside the body. Exudate Fluid, cells, or other substances that have been discharged from vessels or tissues; it contains white blood cells, lymphokines, and growth factors that stimulate healing. Granulation Tissue The fibrous collagen formed to fill the gap between the edges of a wound healing by secondary intention. Capillaries and fibrous collagen project into the wound during the healing process, filling the wound as it heals. Hematoma A mass produced by coagulation of extravasated blood in a tissue or body cavity. Infection The invasion and multiplication of microorganisms in body tissues that cause cellular injury and clinical symptoms. Inflammatory Phase The first phase of the wound healing process (also known as the reactive stage), which lasts one to four days; in this phase, the basic process of inflammation is set in motion. Microorganism An organism that is too small to be seen with the naked eye and requires a microscope. Bacteria, viruses, fungi, and protozoa are generally called microorganisms. 52 Neuropathic Wounds Wounds or ulcers related to the loss of protective sensation in the feet and legs as the result of a primary neurological condition, metabolic disease process (e.g., diabetes and/or renal failure), trauma, or surgery. Phagocytosis The process by which certain cells (e.g., leukocytes) engulfing and destroy microorganisms, bacteria, cellular debris, or other foreign bodies. Platelet A small, disk or plate-like structure, the smallest of the formed elements in blood. Platelets, also called thrombocytes, are disc-shaped, non-nucleated blood elements with a fragile membrane. They tend to adhere to uneven or damaged surfaces. Primary Intention Healing that occurs when wounds are created aseptically, with a minimum of tissue destruction and postoperative tissue reaction. Proliferative Phase The second phase in the wound healing process (also known as the regenerative or reparative stage) that begins within hours of the injury; it allows for new epithelium to cover the wound. Reepithelialization The restoration of epithelium over a denuded area by natural growth. Remodeling Phase The final phase of the wound healing process, also known as the maturation stage; this phase begins after approximately two to four weeks, depending on the size and nature of the wound; it may last one year or longer. During this phase, the scar tissue formed during fibroplasias changes in form, strength, and bulk; the final shape and function of the wound are created. Secondary Intention (Granulation) Wound healing that occurs by granulation, eventual reepithelialization, and contraction, rather than by suturing the wound closed and healing by first intention. Seroma A collection of serous fluid due to inadequate control of lymphatics during dissection; it is frequently seen under split-thickness skin grafts and in areas with large dead spaces (e.g., axilla, groin, neck, or pelvis). 53 Slough Necrotic tissue that is in the process of separating from viable portions of the body. Surgical Wound Wound caused by incision or excision. 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