Download Single-use Negative Pressure Wound Therapy Systems

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
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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.
Tertiary Intention
(Delayed Primary Closure) Wound healing mechanism in which healing,
approximation, and suturing are delayed or
secondary in order to wall off an area of gross
infection or in cases in which extensive tissue
was removed; the wound edges are closed four
to six days postoperatively after thorough
debridement.
Traumatic Wound
Wound caused by mechanical, thermal, or
chemical destruction.
54
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