Inside Insights On Negative Pressure Wound Therapy

Author(s): 
Clinical Editor: Lawrence Karlock, DPM

Negative pressure wound therapy (NPWT) can have a positive effect on wound healing. These panelists detail what types of wounds can benefit from the technology, when to consider negative pressure and how various NPWT devices compare to one another.

Q:

What has been your general impression and experience with using negative pressure wound therapy for lower extremity wounds?

A:

All four panelists have had positive experiences with NPWT. For Eric Travis, DPM, negative pressure therapy is “valuable and consistent” when treating lower extremity wounds. As he says, the foot and ankle pose a unique challenge with traditional dressings. Dr. Travis notes that results with such dressings have been “inconsistent and ineffective” due to uneven topography, shear forces, undrained subcutaneous seromas and unique vectors of wound tension.    Dr. Travis notes that NPWT seems to decrease the amount of proteases and other lytic enzymes that cause cellular breakdown and delayed healing. He adds that the literature on this subject supports this as well. Negative pressure also decreases bacterial load, increases granulation and increases tissue oxygen perfusion and nutrient uptake, according to Dr. Travis.    Calling Vacuum Assisted Closure (VAC) therapy “a wound simplification device,” Lee Rogers, DPM, says the technology makes complicated wounds simple. Within days, he says VAC therapy can convert a wound with exposed structures (e.g. University of Texas (UT) 2A ulcer) into a superficial wound with quality granulation tissue (UT 1A ulcer) ready to accept a skin substitute or a graft. Dr. Rogers says VAC therapy is “extremely effective” at creating or enhancing granulation tissue, and is also effective in preparing the wound bed for advanced closure.    Although VAC therapy (KCI) is contraindicated in “untreated osteomyelitis,” Dr. Rogers says he frequently uses NPWT over exposed bone without surrounding signs of soft tissue infection. He will fenestrate the exposed bone with a 2.0-mm drill in the operating room and if intraoperative hemorrhage is controlled, he places the VAC therapy on the wound. As Dr. Rogers notes, fenestrating or decorticating the bone exposes the marrow, containing mesenchymal stem cells, to the wound bed and can enhance granulation tissue.    Since 1999, Desmond Bell, DPM, has been using the VAC therapy extensively on foot, heel and lower leg wounds in hospital, office and home care settings. Dr. Bell thinks VAC therapy is “one of the true difference makers” and says the technology of negative pressure therapy has paralleled the advancement of wound care as a specialty.    “Negative pressure wound therapy has had a tremendous impact on my patient population as it has been a critical component of many successful outcomes in which the potential for lower extremity amputation was great,” explains Dr. Bell.    Robert Frykberg, DPM, has had an “excellent” experience with NPWT. He uses VAC therapy frequently for conditions such as lower extremity ulcers, post-amputations and dehiscence. He also uses the technology to prepare wounds for delayed closure.    “Like most successful wound care products, NPWT is consistent, effective and versatile,” says Dr. Travis. “I tend to use VAC therapy on the majority of my patients unless insurance or circumstances dictate otherwise. In those cases, I will use a similar device.”    Dr. Travis uses VAC therapy on tunneling wounds, traumatic wounds, amputation wounds that are compromised by inadequate circulation, and for ulcerations associated with diabetes and peripheral vascular disease.    “I really find that VAC therapy has given me a great advantage with skin grafting techniques of the foot and ankle,” he notes. “I feel that skin grafting techniques with NPWT have created a more rapid, secure graft take while removing the negative factors that cause graft failure.”

Q:

When you are evaluating a wound, what factors facilitate the use of NPWT?

A:

In evaluating the potential for wound healing with NPWT, Dr. Bell cites the importance of checking the patient’s vascular status and perfusion to the wound. He adds that clinicians should also consider any sign of viable tissue in a deep wound as a favorable indication of the wound’s potential to heal. Dr. Bell says he has seen numerous wounds that presented initially with a majority of fibrin, slough or other debris but gave way to healthy granulation after consistent use of VAC therapy.    Dr. Bell says one must also address the infectious process. He notes that underlying osteomyelitis is not a contraindication if intravenous antibiotics or surgical treatment of the infection are ongoing. He notes that another benefit of NPWT is fluid/drainage management, especially considering the potential for reduction of matrix metalloproteinsases, which are a deleterious component of wound exudate.    Negative pressure wound therapy would be contraindicated in lower extremity wounds with the presence of malignancy or heavy bleeding, according to Dr. Bell. Dr. Travis also does not use NPWT on malignant wounds and emphasizes that one resolve active wound bleeding before instituting NPWT.    In Dr. Rogers’ center, NPWT fits into the spectrum of ulcer treatments in a narrow window. After excluding or treating ischemia and infection, and after mitigating plantar pressure through offloading, Dr. Rogers says one can address the purely neuropathic wound. He follows a spectrum of treatment for these wounds: debridement, promotion of granulation and wound closure. Dr. Rogers and his colleagues use NPWT as a very effective means of promoting granulation.    “It is not the alpha and the omega, and cannot be used throughout the treatment of a wound,” he says of NPWT. “Having a better understanding of when VAC therapy should be used will make it less likely to fail in wounds in which other modalities may be better suited.”    Dr. Rogers uses NPWT on a deep wound with or without exposed subcutaneous structures, and after it has been debrided of any nonviable tissue. He often combines VAC therapy with bioengineered tissue, collagen or silver products. After the wound becomes completely granular, Dr. Rogers discontinues VAC therapy and closes the wound by any number of means. During wound closure, he says one may continue NPWT briefly if it is intended as a bolster dressing for skin substitutes or skin grafts.    Dr. Travis agrees it is important to debride the wound prior to using NPWT and he utilizes sharp, mechanical or chemical debridement. He does not use VAC therapy on suspicious lesions or vasculitic ulcers.    Dr. Frykberg considers the depth and size of the wound as well as vascularity. He says NPWT is frequently used for management of open post-amputation wounds or post-I&D of infected wounds.

Q:

How do you compare VAC therapy (KCI) with other products that provide negative pressure?

A:

Most of Dr. Travis’ experience is with VAC therapy. He feels the system’s dressings can fit the majority of the wounds he faces and it is a “universal system” that he can adjust according to his needs. Dr. Travis has used the Invia (Medela) and the Versatile 1 (Blue Sky Medical) devices as well, noting they were also effective. However, he says his comfort with VAC therapy and the ability to tailor his treatment make the device preferable.    “In my opinion, the comparison between VAC therapy and other systems is like comparing an automobile to a bicycle,” opines Dr. Bell.    As Dr. Bell notes, VAC therapy and other systems both remove exudates but the similarity ends there. Citing a recent published panel case study series, Dr. Bell notes that researchers were unable to conclude that another brand of NPWT showed evidence to support its use in wound healing.1 He says the sponge used in VAC therapy has proven to be superior to gauze as an interface to the wound bed. Gauze tends to absorb exudates and keep them in contact with the wound while the foam, due to its design and fluid repelling properties, allows for more efficient removal of exudates, according to Dr. Bell.    “Bottom line, there is not a significant body of evidence supporting other NPWT systems in comparison to the large body of evidence that supports the use of VAC therapy,” summarizes Dr. Bell. Dr. Bell is a board certified wound specialist of the American Academy of Wound Management, and a Fellow of the College of Certified Wound Specialists and the American Professional Wound Care Association. He is the founder and Director of the First Coast Diabetic Foot & Wound Management Center, Wound Care on Wheels, Wound Summit Outreach, Inc., and the Wound Care Consortium, all of Jacksonville, Florida. Dr. Bell is also the founder and Course Director of the Southeastern Interactive Wound Summit (SIWS), a multidisciplinary annual conference on advanced wound healing.    Dr. Frykberg is the Chief of Podiatry at the Carl T. Hayden VA Medical Center in Phoenix.    Dr. Rogers is a fellow at the Center for Lower Extremity Ambulatory Research (CLEAR) and a faculty member in the Department of Surgery at the Dr. William M. Scholl College of Podiatric Medicine. Dr. Rogers was an investigator on the randomized, controlled, multicenter trial of Vacuum Assisted Closure (VAC) Therapy in the treatment and blinded evaluation of diabetic foot ulcers.    Dr. Travis practices at Beach Podiatry in California. He is on the teaching staff at Fountain Valley Regional Hospital and is involved in the Wound Care Program at La Palma Intercommunity Hospital.    Dr. Karlock (shown at the left) is a Fellow of the American College of Foot and Ankle Surgeons, and practices in Austintown, Ohio. He is the Clinical Instructor of the Western Reserve Podiatric Residency Program in Youngstown, Ohio. Dr. Karlock is a member of the Editorial Advisory Board for WOUNDS, a Compendium of Clinical Research and Practice.    Editor’s note: For related articles, see “Closing Difficult Wounds” in the March 2006 issue of Podiatry Today and “Combining VAC Therapy With Advanced Modalities: Can It Expedite Healing?” in the September 2005 issue.    Also be sure to visit the archives at www.podiatrytoday.com.

 

 

 

 

 

References:

Reference    1.     Gupta S. Differentiating negative pressure wound therapy devices: an illustrative case series. Wounds 2007; 19, 1 Suppl:1-9.

 

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