Article Archive
November/December 2016

Negative Pressure Wound Therapy for Wound Treatment
By John A. Bennett, MD
Today's Geriatric Medicine
Vol. 9 No. 6 P. 24

NPWT has proven successful among elderly patients who are at greatest risk for skin breakdown and compromise in skin integrity.

Negative pressure wound therapy (NPWT) is a treatment technique that has been used for quite some time to help heal chronic and acute nonhealing wounds including pressure ulcers and bedsores. Chronic nonhealing wounds such as these are especially problematic for elderly patients, as their skin is more easily damaged and their skin cells don't reproduce or respond to stress as quickly as younger people's. Before delving more deeply into the problem of chronic wounds in elderly patients, it is important to note how NPWT has evolved over time in order to fully understand its advantages and disadvantages and perhaps where it will progress in the future.

NPWT dates to 600 BC when the Greeks engaged in a practice known as cupping. Cupping was a vacuuming technique in which the Greeks heated copper bowls and applied them directly over wounds to draw out and remove blood and wound exudates in an attempt to speed the healing process. The real prelude to NPWT occurred at the end of the 19th century when German professor and surgeon August Bier of the Charité-Universitätsmedizin in Berlin refined the cupping technique by igniting alcohol within a glass for heated cups and placed a rubber tube around the wound prior to applying the cups. In 1907 Dr. E. Klapp, Bier's student, first used a suction pump on a wound, and by the 1970s, physicians were using drainage canisters to help with tissue repair.

As negative pressure treatment evolved, so did the dressings and the ways in which clinicians applied them. The original NPWT dressing was a giant piece of medical gauze that had been placed in the wound bed with polyurethane foam, an open-cell dressing used in this therapy, laid over the top with tubing protruding horizontally and sealed with caulk around the tubing to create the proper environment in which to begin treatment. Since then the black foam, the same polyurethane foam mentioned above, has been used to fill open cavity wounds and can be cut to size to fit wounds, eliminating the need for gauze. The foam serves as a contact surface between the tissue and the skin because without it, the suction would be unable to reach the tissue if there weren't a medium in place to make the connection.

When it is applied, the foam dressing contracts the wound and the growth of the granulation tissues and absorbs the exudates. A film drape is applied on top of the foam to create a seal around the dressing. Tubing connected to the wound vacuum exits vertically, with the fluid and wound exudates collected in the disposable canister. NPWT creates tension and compression of the tissue that lead to formation of granulation tissue. The key to managing successful promotion of wound healing lies in creating a complete seal at the wound site for the wound vacuum. This can be challenging because the skin is not uniform and creating a vacuum in areas such as the foot can be difficult. The variety of dressings and applications are critical elements in creating a tight seal to successfully promote wound healing with NPWT.

Black foam dressings have become a standard dressing application globally. The foam pieces are available in different sizes and can easily be cut by a clinician. To take the advancements of dressings even further, the author has created a patented, one-of-a-kind bandage dressing for Devon Medical Products' extriCARE NPWT product line. The integrated contoured NPWT bandages are constructed with a nonwoven polyurethane matrix pad secured on the outside surface to a sheet of polyurethane film formed with an outer adhesive boundary to establish a seal against the patient's skin around the wound site. The inner surface of the nonwoven matrix pad is covered with a silver nitrate mesh to promote healing of the wound site when the bandage is placed on top of the wound.

A drain tube is contained within the nonwoven matrix pad for connection with a source of negative pressure to withdraw the fluids and exudates from the wound for removal to a canister located remotely from the bandage. Contoured versions of the integrated bandage are provided for use on portions of the body that are difficult locations for application of NPWT, such as the toes, heels, limbs, and sacral region. NPWT has become an effective measure in treating difficult-to-heal wounds, but is especially effective in the elderly. With the advancements in NPWT, the treatment method addresses a multitude of wounds, offering greater flexibility to patients.

Proven Efficacy
The four primary elements that contribute to NPWT's success are wound shrinkage or macrodeformation, microdeformation at the foam-wound surface interface, fluid removal, and stabilization of the wound environment. Some equally important secondary elements that occur with NPWT are angiogenesis, neurogenesis, granulation tissue formation, cellular proliferation, differentiation, and migration.

Macrodeformation occurs by forcing the wound to shrink during NPWT treatment, caused by the collapse of the pores and centripetal forces exerted on the wound surface by the foam. Studies have shown that foam exposed to suction can significantly decrease the foam volume and result in a decrease in the wound surface area.1 This is important because the natural tension in the skin causes wound margins to pull apart, and different wounds contract to different degrees. Wounds typically contract as they heal, with the surface area decreasing. NPWT accelerates this effect. A study by Lu et al showed wound area in patients under NPWT was "2.5 times more likely to be reduced within one week compared with standard moist therapy."2

Microdeformation describes the way the wound tissue reacts at the microscopic level. During the application of micromechanical forces, cells respond to applied stress of mechanical cues to help promote wound healing. Studies have suggested that NPWT influences the microenvironment of wound healing by removing inflammatory proteases and reducing bacteria while providing a moist environment, increasing blood flow, and causing stimulation of granulation tissue for cell proliferation. These physical effects cause a deformation that signals a variety of molecular responses including stimulation, alterations, and strain on the wound bed, accelerating the healing of the wound.

Fluid removal is incredibly important because excess fluid or edema and chronic wounds generally occur together, but too much fluid can cause the wound healing to be slowed. The seal that the dressings create allows for continuous evacuation of fluid, including toxins and bacteria, which can help speed the healing process.

Stabilization of the wound environment is the last crucial element that occurs once fluid removal is complete. Extraction of fluid in the wound bed with its accompanying electrolytes and proteins, in theory, also stabilizes osmotic and oncotic gradients at the wound surface.

NPWT is not the only wound treatment available, but there are complications with other wound treatment methods when it comes to chronic nonhealing wounds such as pressure ulcers and bed sores that are virtually nonexistent with NPWT. Most other wound-healing techniques take much longer. It can take weeks or months of daily dressing changes before a wound begins granulating and appears clean enough for it to begin even closure. This poses a risk of infection, which prolongs the wound healing process. If infection occurs, control of chronic wound contamination becomes the focus. NPWT may help heal wounds more quickly than other types of treatments; this aids in preventing potential infection and contamination.

Prevention Is Key
Of course, standard protocols to prevent the occurrence of such wounds need to be followed first and foremost. These protocols include repositioning patients who are bedridden every two hours to help minimize pressure on the skin and maintain circulation to areas that are at risk for breaking down, ensuring proper nutrition to support skin health, and maintaining proper skin moisture.

Despite these protocols being followed religiously, 5.7 million patients suffer from chronic wounds,3 which increases the importance of NPWT.

Prior to the use of NPWT, basic techniques to manage these types of wounds were restricted to maintaining a moist wound environment, performing surgical debridement, and skin grafting exposed tissue.

NPWT has been found to be the most effective because it augments the process of wound contraction and closure and is seen as an aid to healing skin grafts and the vascularization of synthetic skin substitutes such as animal skins.

As mentioned earlier, elderly patients experience more difficulty healing from chronic wounds such as pressure ulcers and bedsores solely because of their age. Skin breakdown and a total compromise in skin integrity are common in older patients with diseases such as diabetes and peripheral artery disease.

A recent study found that nearly 70% of all pressure ulcers occur in the geriatric population. As a function of aging, elders' skin has less water content, strength, and integrity between the dermis and epidermis.4

Benefits to Elderly Patients
Cost is always an important aspect of any treatment. Focusing on the elderly in nursing homes, the author found that these patients were in many cases denied this life- and limb-saving technology because of the cost and the difficulty in administration. The rising costs of health care and of medical devices provided incentive to develop less expensive equipment and procedures that are more easily utilized to reduce the costs associated with using NPWT, while improving on the effectiveness of the therapy. The goal was to bring to the aging population the technology available in Haiti.

Efforts included trying to make the devices simple to operate, light in weight, and easy to apply while at the same time greatly reducing the price. At the time, KCI dominated the industry but their NPWT pumps cost $25,000 and, it seemed, were complicated to operate. They also used only a complicated foam bandage system that was difficult to apply.

From the drawing board evolved the creation of a lightweight device that was easy to operate and a bandage system that was like a Band-Aid to apply to the patient. Simplification of the procedures and the equipment would allow portable use of such therapies with a minimum of professional supervision and monitoring of patients. Furthermore, patients and nursing homes continue to demand devices that are more easily mobile while utilizing the therapy. Combining the demands of clinicians and patients produced a device that reduced the costs from $25,000 to $1,000. NPWT can now be commonly available to the elderly, and its light weight encourages patients to maintain their lifestyles, accelerating the healing process.

A Clinical Challenge
It's important for physicians to create a comprehensive wound care program that teaches clinicians how to address and treat different wound types and ways to best identify changes in the wound healing process. Managing and treating chronic wounds, including decubitus ulcers, remains a challenge because of the multitude of factors and wound types. Nonbearing, chronic pressure ulcers present a continuous challenge in global health care, especially with decreasing mobility and the effects of aging on elderly patients' skin. Although there are no known published clinical trials of NPWT healing wounds in elderly, there are numerous patient studies and case studies that support NPWT as a treatment method.

Health care professionals globally are increasingly adopting NPWT as a preferred treatment method. Experts estimate that the current market for NPWT products exceeds $3 billion worldwide and is projected to grow 10% per year over the next five years.5

The next generation for NPWT is smart-enabled devices. For the first time ever, clinicians, especially those caring for elderly patients, will have the opportunity to take advantage of home wound care. Technology is advancing and real-time monitoring capabilities are disrupting the NPWT medical device market. A smart NPWT pump will make it easier to acquire and manage the pump asset, track usage, provide technical support, and maintain the documentation essential to reimbursement. It is essentially a mobile device equipped with a cellular modem to connect in real time to a cloud application that provides continuous operating status and immediate notifications to caregivers for more effective coordinated care.

Automation through cloud services will streamline processes and lower costs. Clinicians prescribing the smart pump will know whether patients are adhering to treatment plans and can play a more active role in the healing process with real-time driven data. The correct information at the right time will allow for better coordination of nurse visits with patient needs, leading to fewer readmissions and avoidance of complications and costly interventions.

— John A. Bennett, MD, is president and CEO of Devon International Group in King of Prussia, Pennsylvania, and a recognized entrepreneur whose experience in health care spans more than 35 years. With his career launched as an emergency department physician, he was elected to Delaware County Memorial Hospital's medical executive committee and named director of emergency services. He founded ATI Centers, a group of outpatient diagnostic imaging and physical therapy centers located in Pennsylvania and New Jersey. He has expanded business operations across the globe in industry sectors such as genetic testing, medical device manufacturing, and virtual desktop software.

1. Huang C, Leavitt T, Bayer LR, Orgill DP. Effect of negative pressure wound therapy on wound healing. Curr Probl Surg. 2014;51(7):301-331.

2. Wiegand C, White R. Microdeformation in wound healing. Wound Repair Regen. 2013;21(6):793-799.

3. de la Torre JI. Chronic wounds. Medscape website. Updated October 1, 2015. Accessed August 24, 2016.

4. Gist S, Tio-Matos I, Falzgraf S, Cameron S, Beebe M. Wound care in the geriatric client. Clin Interv Aging. 2009;4:269-287.

5. Negative pressure wound therapy (NPWT) market: fuelled by growing demand for NPWT devices in homecare settings: global industry analysis and opportunity assessment 2016–2026. Future Marketing Insights website. Published May 4, 2016. Accessed August 24, 2016.