Focus On…Wound Care: Negative Pressure Wound Therapy: An Option for Hard-to-Heal Wounds
|Negative Pressure Wound Therapy (NPWT) is a topical treatment used to promote healing in acute and chronic wounds. It involves the application of negative pressure (suction) to the wound bed. The concept is to turn an open wound into a controlled, closed wound while removing the excess fluid from the wound bed, thus enhancing circulation and disposal of cellular waste from the lymphatic system.1 NPWT consists of a nonadherent, porous wound dressing; a drainage tube placed adjacent to or inserted into the dressing; an occlusive transparent film used to seal the wound and the drainage tube; and a connection to a vacuum pump that supplies the negative pressure. This technique is usually considered only for chronic, acute, and difficult-to-heal wounds. The common applications for NPWT appear in the table.1|
The use of negative pressure to promote healing of open wounds has a proven track record for efficacy and ease of use. This article discusses how NPWT works and reviews the documented benefits of this therapy. Two case studies are presented that demonstrate NPWT's efficacy.
How Does NPWT Work?
The V.A.C. system is applied to an open wound for periods of 48 hours. Suction is directed at the surface of the wound through an interface between the wound surface and either a black polyurethane or white polyvinyl alcohol foam that is cut to the appropriate shape of the wound and is then inserted to contact the entire wound. The less dense, more porous black foam is more commonly used on larger or deeper wounds; the white foam has better nonadherent properties that help protect skin grafts and promote graft survival. The foam allows for distribution of the negative pressure. Suction tubing is placed onto or in the foam, and then the entire wound/foam complex is covered with a clear plastic dressing to seal the wound. It is then connected to a suction pump for 48 hours at either constant or intermittent suction. Suction levels of -125 to -150 mmHg are usually applied. The drainage from the wound goes into a canister attached to the suction pump. Several variations in the size of the pumps and canisters allow for different levels of activity and different treatment locations.
With the Versatile 1 device, a single layer of gauze is placed over the wound, then a flat, silicone Hemovac drain is placed on the gauze over the maximum dimensions of the wound. A second piece of gauze is placed over the drain, creating a gauze "sandwich" around the drain as shown in figure 1. The gauze and drain are entirely covered with a clear, semipermeable dressing that is cut to fit the dimensions of the wound, with a small overlap onto the adjacent healthy skin creating a seal over the wound. The drain is connected to the tubing, which is then connected to the vacuum pump. The gauze is puffy before the vacuum pump is turned on. After the pump is turned on and suction is applied, the cotton gauze collapses and compresses the wound bed. Edema fluid is removed through the drain as shown in figure 2.
Figure 1. Schematic drawing shows the positioning of the Hemovac drain between the two layers of gauze.
Figure 2. Schematic drawing shows a wound to which negative pressure wound therapy is being applied.
Benefits of NPWT
The use of negative pressure to promote healing of open wounds has considerable literature support for efficacy. The effects of NPWT are thought to promote wound healing through multiple actions, including the removal of exudate from the wounds to help establish fluid balance,2 provision of a moist wound environment,3 removal of slough,3 a potential decrease in wound bacterial burden,4 a reduction in edema and third-space fluids,5 an increase in the blood flow to the wound,3-7 an increase in growth factors,8 and the promotion of white cells and fibroblasts within the wound.9 Negative pressure brings tissue together, promoting coaption, which allows the tissues to stick together through natural tissue adherence and increases healing.
There are multiple anecdotal reports and case reports of marked enhancement of wound healing with use of NPWT; however, there are relatively few controlled trials. Gray and Peirce recently conducted a review of the literature currently available on NPWT.5 Results in the studies they reviewed suggest that NPWT may be superior to saline-moistened gauze in promoting healing of chronic wounds, and NPWT may be superior to topical antimicrobial agents and gauze in promoting healing of soft-tissue flaps and skin grafts.5 Philbeck et al found that "healing time can be as high as 61% faster and 38% less costly with combination treatment utilizing a controlled-suction drain system."10
Case Report 1
The Versatile 1 Wound Vacuum System was chosen for this patient because it can be used to provide active therapy at night while a patient is sleeping. This was an important consideration for a patient who has limited mobility. The wounds were treated with the Chariker-Jeter technique2 by applying saline gauze in a single layer covering all aspects of the open wounds. A flat Jackson-Pratt drain was placed on the gauze, and each wound was covered with a clear, semipermeable dressing. The drains were then connected to the negative pressure device at a pressure of -80 mmHg for a period of 6 to 8 hours per day (usually at night while the patient slept). In the morning, after negative pressure therapy was ended, the patient's wounds were redressed with moist saline gauze covered with a Tegaderm (3M) dressing for the remainder of the day. He would clamp the flat drain tubing before disconnecting the suction, thus allowing negative pressure to be maintained within the system without ongoing connection to the vacuum pump, and he would coil up the tube and tape it onto the wound dressing (nursing assistance might be required for this, for patients who cannot manage their own disconnection). Being unattached to the vacuum pump during the day allowed the patient greater ease in maneuvering his wheelchair.
After approximately two and a half months of NPWT, the patient's ischial decubitus wound was healed (figure 4, A), and the lateral malleolar wound was rapidly healing. Less than two months later, the malleolar ulcer was completely healed (figure 4, B).
Case Report 2
Figure 3. Photos show wounds on the patient's buttock (A) and ankle (B) as they appeared on October 15, 2003, before NWPT.
Figure 4. Photos show how the wounds on the patient's buttock (A) and ankle (B) appeared after NPWT, on December 31, 2003, and February 18, 2004, respectively.
Figure 5. Photos show wound on patient's leg as it appeared at initial evaluation, before initiation of V.A.C. therapy.
The wound began to granulate rapidly. This was accompanied by a decrease in the patient's pain. The V.A.C. was used for eight weeks, bringing the patient to complete wound closure (figure 7).
In 1985, Dr. Katherine Jeter explored a unique combination of products to deliver negative pressure to the wound bed. Together with Dr. Mark Chariker, she designed a clinical study in which they stated that "their closed suction wound drainage system revolutionized the management of enterocutaneous fistulae complicating ventral abdominal wounds."14
In 1986, Kostiuchenok et al found that NPWT in combination with surgical debridement significantly reduced the bacterial burden within purulent wounds and resulted in improved wound healing.4 Also in 1986, Davydov and colleagues found that vacuum therapy reduced the bacterial load and septic complications, reduced time to healing, normalized the immune process, reduced scar tissue formation, and reduced hospital stays.9
Figure 6. Photo shows the application of the V.A.C. device to the wound.
Figure 7. The wound is completely healed after 8 weeks of V.A.C. therapy.
In 1997, Morykwas and Agenta6,7,15 of Wake Forest University published three articles regarding their experience with a "new method for wound control and treatment…."6 A system was described in which subatmospheric pressure was applied through a closed system to an open wound for periods of 48 hours.6,7 The subatmospheric pressure was directed at the surface of the wound through an interface between the wound surface and a polyurethane sponge, allowing distribution of the negative pressure and use of either a constant or intermittent mode. The authors determined that "the application of controlled subatmospheric pressure creates an environment that promotes wound healing.6
By 2003, NPWT was commonly accepted therapy despite the few randomized, controlled studies of its efficacy. An NPWT consensus group was formed that year in Canada. Their consensus paper contains a literature review, recommendations for specific chronic wounds, and survey results from the group based solely on the V.A.C. product.16
|Table. Appropriate applications for negative pressure wound therapy (NPWT)1|
Patients with other medical problems, i.e., diabetes, coronary artery disease, or renal disease, may be more susceptible to wound dehiscence and delayed wound healing. NPWT may provide increased wound stability.
At the present date, the question is not whether negative pressure wound therapy is beneficial in wound healing, because numerous case studies and articles clearly document its efficacy. The questions that remain involve determining the optimum mechanism and protocols for deploying this therapy. In a recent review article,17 we have called for further research to better define the parameters for pressure intensity, duration of treatment, interval between treatments, mode of application, and timing of application to provide the most efficient and cost-effective therapy. Although there is still much to learn to optimize NPWT, this therapy is currently improving outcomes for patients suffering with pressure ulcers and other difficult-to-heal wounds.
Michael S. Miller, DO, FACOS, CWS, is the Medical Director, Marta Ortegon is a Physician Assistant, and Cheryl McDaniel is a Staff Nurse at The Wound Healing Center, Terre Haute, Indiana. Thomas Serena, MD, FACS, CWS, is the Medical Director at Penn North Centers for Advanced Wound Care, Warren, Pennsylvania. For more information, phone Dr. Miller at (812) 234-4321 or fax (812) 478-9552. To send your comments to the authors and editors, please e-mail firstname.lastname@example.org. To order reprints in quantities of 100 or more, call (866) 377-6454.
The new design of Unistik« 3 lancets includes Safe-Tec Clinical Products' Comfort Zone Technology«, a pain-masking feature that provides a comfortable level of stimulation to the sample site that disguises the pain of lancing. When pressed against the sample site, eight raised dots stimulate the nerve endings to send a message of comfort to the brain.
Other features of the Unistik 3 include visual lockout, automatic needle retraction, and SecureLock to eliminate accidental firings during transport. The Unistik 3 is preset and does not require any cocking procedure.
Good nutrition is essential to skin integrity and wound healing. Decubi-Vite«, from QCE Laboratories, combines the typical protocol of a therapeutic multi-vitamin plus 500 mg of vitamin C and 200 mg of zinc sulfate in one capsule. Residents take one pill instead of three. If swallowing is a problem, the capsule can be easily opened and mixed with applesauce or pudding, or added to water for G-tube administration.
Decub-AmineÖ protein supplement enhanced with arginine, glutamine, and essential fatty acids provides a complete nutritional supplement program.
|Spray-On Moisture Barrier|
Touchless Care Systems' Rash Relief« protects skin with its concentrated 25% zinc oxide and 20% dimethicone formula. Spray-on, no rub-in application only takes a few seconds, saving nursing time. Additional savings are achieved by eliminating the residual waste and cleanup expense of traditional products. Each 4.5-oz bottle delivers more than 100 adult applications.
|F314 Compliance Guide|
Revised F314 guidelines state that a resident should not develop pressure ulcers "unless clinically unavoidable and that the facility provides care and services." Pressure Relief and Reduction: A Guide to Skil-Care Products as Interventions for F314 Compliance can assist caregivers in selecting seating and position devices and pressure-relief surfaces that can prevent pressure sores and aid in the healing of existing ulcers. This guide matches specific interventions to the SOM Guidance to Surveyors. It also provides clinical rationales for each intervention.
This comprehensive guide for F314 compliance is available without cost or obligation from Skil-Care Corporation.
DawnMist« Instant Alcohol Gel Hand Sanitizer from Donovan Industries kills germs that cause infections such as MRSA and VRE, yet it is gentle on the hands. The intensive moisturizing formula contains emollients such as glycerin and aloe vera, plus vitamin E for healthy skin. It is available in a variety of sizes and applicators, including pump and wall dispensers.
Span-America has added 22"- and 28"-wide cushions and an armrest to its Geo-Wave« product line for use with specialty recliners. Used for various applications such as dialysis, chemotherapy, cardiac care, and gerichairs, the Geo-Wave is designed to address shearing in the reclined position. The armrest pads adjust to various widths for user comfort.
Replacement Mattress James Consolidated, Inc., has introduced the V÷lkner Turning System Delta II low-air-loss mattress replacement, which has a blower type pump with 1275 LPM airflow. The digital electronic control unit features maximum inflate; lateral rotation of static air flotation; up to a 40¦ turning angle; and a 10-, 20-, 30-, or 60-minute turning cycle to the right, left, or both sides.
DM Systems, Inc.'s new Heelift design includes extended stitching along the top rim of the boot to narrow the forefoot, offering improved protection against foot drop, equinus deformity, or heel cord contracture. The extended stitching also prevents the foam from tearing through the ventilation holes. The simplified strap design permits one-handed closure and easier adjustment of the strap's tension.
Heelift and Heelift Smooth Suspension Boots are used to prevent and treat heel pressure ulcers. Pressure is eliminated from the heel by lifting it with an elevation pad and suspending the heel in protective space. In prevention regimens, Heelift can be used with residents who are immobile, postoperative, or suffer from diabetes, cardiovascular disease, or dietary deficiencies.
|Compression Therapy Equipment Rental Service|
Med Supply of Tampa, Inc., offers Vascular PRN, a service providing compression therapy equipment for rent or sale with overnight delivery. The service offers KCI's Extremity Pump System 7000 Intermittent Compression and System 7500 Sequential Compression for treating lymphedema.
KCI's PulseICÖ for intermittent vascular compression and the PulseSCÖ for sequential vascular compression are available for vascular therapy. KCI's most effective unit, the PlexiPulse«, provides foot, calf, or foot and calf compression. It replicates the action of venous plexus in the foot, which is especially valuable for patients who cannot ambulate.
A video showing venograms of a patient receiving this therapy is available at no charge from Vascular PRN.
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