Vacuum-Assisted Closure Used for Healing Chronic Wounds and Skin Grafts in the Lower Extremities
Among the current adjunctive treatment modalities available for the treatment of chronic wounds, vacuum -assisted closure (VAC, V.A.C.®, KCI, San Antonio, Tex.) therapy has shown promising results.1,2 Vacuum-assisted closure is most frequently recommended for use with chronic wounds, acute and traumatic wounds, flaps, grafts, and other non-sutured wounds such as dehisced incisions.3-5
In the authors' facility, VAC therapy is used mainly for clean, chronic wounds. Before initiating treatment, underlying problems that contribute to poor healing are treated or corrected as much as reasonably possible. Because vacuum-assisted closure devices involve daily rental costs, the treatment in the authors' practice has been reserved for larger chronic wounds only (area >14 cm2 and depth of at least 3 mm). One exception to this rule has been skin grafts. Placement of the VAC device at the recipient site occurs at the time of grafting and continues without a dressing change for 7 days. Other clinicians also have reported use of VAC as a dressing for skin grafts in various wounds.6-8 The wounds receiving skin grafts in the authors' facility differ from those reported in the literature in that they are chronic wounds that are managed with VAC therapy before grafting. Observations about the technique's ability to initiate and augment granulation tissue formation have been reported.9,10
Early experiences in the authors' facility with this technique prompted the use of several adjunctive materials when healing appeared to be slowing or when infection appeared likely. These adjuncts include silver fabric dressings (Silverdon®, Argentum Medical Ltd., Lakemont, Ga.) when bacterial burden or infection risk appear high, the routine use of silver-coated dressings for initial skin graft management with VAC therapy, and chlorophyllin-urea-papain ointment (Panafil®, Healthpoint Ltd., Fort Worth, Tex.) when healing tissues appear viable but progression to healing appears to have slowed.11,12 The authors conducted a retrospective chart review in their wound care practice to document the efficacy of these techniques when used with VAC therapy.
During a period of 30 months, 70 patients with chronic wounds greater than 14 cm2 were treated using VAC. Data from all 70 consecutive patients were retrospectively reviewed and tabulated. Fifty of these 70 patients received skin grafts followed by VAC as the initial graft dressing. All patients provided informed consent for their procedures, review, and educational use of their cases and were initially referred and seen weekly by the same physician.
Patient demographics. Thirty-two of the 70 patients were initially seen as inpatients. All others were first seen and managed as outpatients. Wound size varied from 6.0 cm x 3.2 cm x 0.75 cm to 40 cm x 16 cm x 3 cm (average = 22.5 cm3). Wounds included diabetic foot and ankle wounds (23); arterial lower leg wounds (8); traumatic leg wounds (8); pressure wounds on the sacrum, hips, and legs (7); venous ulcers (7); and wounds secondary to cellulitis, abscess, and necrotizing fasciitis (17).
Patient ages ranged from 15 to 83 years old (average 54 years old) and 40 were men. Additional morbidities included 31 patients receiving treatment for coronary artery disease, 25 with diabetes mellitus, 18 with low (< 70% of normal) serum pre-albumin and albumin, 11 with renal failure requiring dialysis, and eight with paresis affecting the area involved. Twelve patients received corticosteroid treatment (prednisone). Corticosteroids were discontinued in six patients and the dosage was reduced to 10 mg or less daily in the other six patients. Patients who continued prednisone treatment also received vitamin A (25,000 units daily by mouth) in an attempt to lessen the effect of the steroids on healing during the first month of VAC treatment. Chemotherapy for cancer was stopped for the first 3 weeks of VAC therapy on five patients (see Table 1).
Treatment procedures. All patients had received appropriate wound care for at least 6 weeks before instituting VAC therapy. Specifically, during this time, underlying conditions contributing to poor healing were corrected (eg, all pre-albumin values were brought into normal range, adequate debridement was performed, moist wound healing was implemented, pressure was unloaded, active infections were treated, ischemia was corrected as much as possible, and edema was controlled). Patients with diabetes had adequate glucose control (Hg A1c < 7% at start of VAC therapy). All VAC dressing changes were performed using the larger pore ("black") sponge dressings and all units were set at 125 mm Hg continuous negative pressure. The dressings were changed three times a week on granulating wounds and not changed over skin grafts; in the latter instances, the dressing was left intact for 7 days and then removed. Wounds were cleansed and measured at each dressing change. Cleansing procedures included a light and gentle wash with Technicare® soap (Care-Tech Labs, Inc., St. Louis, Mo.) for 1 minute followed by a thorough rinsing with normal saline solution. If a silver product was used in the wound, sterile water, not saline, was used for rinsing. Maintenance sharp debridement was performed at every weekly dressing change if necrotic tissue or slough was noted. The presence of foul odor associated with cloudy discharge or erythematous edges was an indication for obtaining wound cultures and changing the dressings daily until symptoms subsided. On 22 patients with these symptoms, silver-coated cloth dressings were applied between the sponge and the wound until symptoms subsided. In five patients, culture results and clinical symptoms indicated an overt uncontrolled infection and appropriate systemic antibiotics were prescribed.
When granulation tissue formation appeared to cease and wound size either increased or remained unchanged over a period of 10 days, and no evidence of excessive discharge, slough, or necrosis was noted, a thin layer ("see-through thinness") of chlorophyllin-urea-papain ointment was applied over the wound bed before sponge application at each dressing change until wound healing and closure became progressive again (46 patients).
Skin grafts. Split-thickness skin grafts (1/12,000-inch thickness) were performed in the operating room. Patients were offered skin grafts when granulation tissue appeared to compensate for tissue defect. All grafts were taken at 1/12,000 -inch thickness with a dermatome and meshed 1.5:1. Grafts were applied under a layer of meshed silver-plated cloth and sewn into place with nylon suture. A VAC device was applied according to the manufacturer's directions, kept in place for 7 days, and removed. One dose of appropriate antibiotic was given 1-hour preoperatively in skin graft patients.
The wounds of 10 of the 70 patients evaluated closed without additional interventions within 26 to 68 days of commencement of treatment (average 48 days). The average size of these wounds was 12.5 cm x 7 cm x .8 cm. Five patients died during the course of treatment; two died from overwhelming sepsis (not wound related) and three died from cardiac (two) and cerebrovascular (one) complications. The wounds in 50 patients healed to the point that skin grafts could be offered. All wounds were grafted and skin grafts remained viable, healed, and closed with persistent, adequate healing for at least 6 months (6 months is the shortest follow-up period, range 6 months to 3 years). All skin graft sites were fully epithelialized after 11 to 24 days (average 17 days). The skin-graft group included five patients with heel ulcers and 15 patients who had skin grafting over knee or ankle joints.
In 10 diverse patients who had not shown any signs of granulation tissue formation before the vacuum closure technique was used, an early conversion to new and progressive formation of granulation tissue was noted within 2 weeks of initiating this treatment. No episodes of wound-related sepsis occurred, but episodes of cellulitis did occur in five patients. Cellulitis was treated with a course of systemic antibiotics without discontinuing VAC therapy. No episodes of graft site infection or other significant cause of graft loss were noted. Five patients failed to progress to healing after 3 months of VAC treatment; three of these patients had diabetes mellitus with renal failure on dialysis and two patients had large pressure ulcers (one sacrum and one hip) with periodic progressions toward healing. However, overall progress did not justify continued use of VAC therapy. The latter two patients received successful flap closure of their wounds. The three patients on dialysis who did not heal had the affected body part amputated. Patient progression in this study is shown in Figure 1. Representative pictures of patients and results are shown in Figures 2, 3, and 4.
This case series included chronic wounds healing by secondary intention and skin grafts applied on chronic wounds (see Figures 2, 3, and 4). The use of VAC therapy to heal wounds and as the initial dressing for skin grafts has been reported in a few patients in mostly acute and some chronic wounds.6-8 The outcomes achieved using the management strategies discussed were encouraging. All skin grafts healed without infection using only a preoperative dose of antibiotics and application of a silver dressing only. The latter may have had a beneficial effect on chronic wounds with a heavy bacterial load as well as on the skin grafts. Potential infection and destruction of skin grafts may have been controlled using the silver-plated cloth (see Figure 4).
In addition, chlorophyllin-urea-papain ointment was used under the vacuum closure sponge to stimulate wound healing when progress appeared slow. When healing progress slows, a "VAC holiday" is often recommended by the manufacturer. In the authors' facilities, the ointment is applied and therapy continued. This approach appears effective but neither the "holiday" nor ointment application approach has been studied in a controlled fashion.
It is noteworthy that an additional benefit of using a VAC dressings over wounds in neuropathic extremities, as seen in the diabetic foot and heel wounds, is that it constantly reminds the patient that a wound is present and that offloading is needed.13
Some have argued that VAC should be used on clean granulating wounds only. The results of the authors' record review suggest that it can be used on wounds that do not contain granulation tissue, providing they are free of necrotic tissue. Of course, underlying factors that may negatively effect healing had been controlled as much as possible (see Figure 4). Several factors, including increased vascularity and rate of granulation tissue formation, as well as decreased inflammation, have been considered to contribute to the effects of vacuum-assisted closure on wounds.1,2,9,14
It also has been reported that on-and-off intermittent cycling of the vacuum equipment enhances healing as it improves blood flow to the area.15 This has not been the case in the current set of patients, and cycled treatment is rarely used. In fact, all of the failures in this study had at some point undergone cycled therapy, but it did not help.
In this review, VAC therapy appeared to be a useful modality in the authors' treatment of larger chronic wounds, as well as a stabilizing dressing when used for subsequent skin grafts. When compared to the goals and steps in the current literature pertaining to wound bed preparation, VAC therapy appeared helpful in removing excess exudate, increasing granulation in some wounds that had not been granulating and protecting the wound from trauma and contamination.7, 16,17
Other studies have shown that VAC-treated wounds resist bacterial overgrowth; as healing progresses and the wound becomes "healthier."1,2,5 The authors' experience with chronic wounds and wound grafts indicates that infection is not always thwarted using this therapy and that adjunctive use of silver products and ongoing removal of slough by maintenance sharp debridement is necessary.
Vacuum-assisted closure is valuable in the healing of chronic wounds and provides an effective stabilizing dressing for skin grafts over chronic wounds. Actively healing wounds also appear to resist infection; however, silver products may be necessary to help control suspected bacterial burden. Using VAC appears to increase wound bed perfusion and vascularity, but it is of little consequence in an ischemic body part and should not be used in such cases unless the ischemia can be corrected. Overall, use of VAC appears to assist in wound bed preparation as well as promote healing of wounds. Its effectiveness, including use as the initial dressing over skin grafts, particularly on chronic wounds, is also noteworthy. Additional studies are warranted and encouraged.