How To Use VAC Therapy On Chronic Wounds

Volume 15 - Issue 7 - July 2002
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An Eight Step Approach To Using VAC Therapy

Here is a step-by-step approach of the standard technique we use to apply VAC therapy at the Southern Arizona Veterans Affairs Medical Center.

1. Debride. As in every wound except for the most ischemic, debriding is essential. You should surgically and/or biologically (using larvae) debride the wound prior to applying the vacuum assisted closure device.

2. Wash. A thorough lavage/cleansing of the wound is important to reduce overall bacterial colonization and to further remove non-viable matter.

3. Cut and shape. The next step is to cut and shape the polyurethane (black) or polyvinyl alcohol (white) VAC sponges. We generally prefer the polyurethane sponge for many of our deeper wounds. Once you cut the sponge to the appropriate shape of the wound, it is a good idea to trace the outline of the sponge on paper or acetate. This serves two purposes. First, it allows us a way to record general wound size. Second, it serves as a template for the next dressing change and will therefore speed up the process.

4. Consider the periphery. We have found maceration appears in nearly 20 percent of the wounds in which the VAC is applied in our center. We have nearly eliminated this issue by using two techniques. First and most commonly, we will apply strips of a hydrofiber dressing (Aquacel, ConvaTec) around the periphery of the wound. The other, perhaps more widely used technique, is using a heavy ostomy-barrier paste. Either of these works. However, using the dressing makes secondary dressing changes and wound assessment a bit easier.

5. Apply the occlusive dressing. Lightly apply the dressing over the sponge and wound. Do this gently, trying to lay the adhesive dressing down like a blanket instead of a tent. This helps to reduce any free air spaces which can make a good seal difficult. This step (over irregular surfaces such as the foot) often requires multiple sheets of dressing. It often may require the complete covering of the foot. If this occurs, remember to reduce interdigital maceration by inserting lambswool or additional VAC sponge between the toes.

6. Insert the VAC line into the dressing and seal. Using a tenotomy scissor or scalpel, incise the occlusive dressing and the outer portions of the sponge to facilitate insertion of the VAC line. After insertion, you may apply another occlusive dressing around the portal. It often helps to pinch off the occlusive dressing at the VAC line’s entrance to the sponge, forming a sort of “omentum” of occlusive dressing. Under this omentum, you may consider using additional sponge to pad and protect the patient from pressure secondary to the tube.

7. Connect the lines and the reservoir. Snap the line to the reservoir and insert the reservoir into the unit until it clips into place.

8. Fire up the VAC and watch it suck. We generally will begin with a continuous setting at 125mm Hg, changing to intermittent after 24 to 48 hours. We have modified these settings slightly when using the VAC with other advanced wound healing modalities such as Dermagraft, Hyaff or Apligraf. If the pressure doesn’t rapidly ramp up to its appropriate setting, consider a poor seal to be the most likely culprit. Try manipulating the tube/dressing interface and if necessary, add additional occlusive dressing to complete the seal.

You can perform the dressing change in nine to 14 minutes and one to two people are required. The dressing change interval at our center was q 48-72 hours.

Here you can see a large, complex diabetic foot wound after emergent intraoperative debridement.

Forty-eight hours after beginning VAC therapy, we see the first dressing change (for the same patient) with steri-strips applied to this rapidly-closing wound.

The authors advocate using the Aquacel dressing prior to applying VAC foam in order to avoid maceration.

A new model of VAC therapy, the VACATS (Advanced Therapy System), features more sophisticated controls for speed and force of suction.

Here you can see the third dressing change one week after the patient began using VAC therapy. The patient was discharged from the hospital at this time.

Author(s):

By Brian Short, DPM, Matthew Claxton, DPM, and David G. Armstrong, DPM

Chronic wounds such as diabetic foot ulcers, venous stasis ulcers and decubitis ulcers are leading causes of morbidity and mortality in elderly patients and significantly contribute to health care costs.1-4 Wounds of these types often lead to complications such as infection and amputation.5-7 The ADA currently reports diabetes is prevalent in at least 17 million Americans, many of whom do not know they have the disease. Of these, approximately 15 percent will experience a foot ulcer or other complication requiring hospitalization during the course of the disease.8, 9
Similarly, venous wounds affect a large population. A recent investigation in Great Britain found the annual prevalence of venous stasis ulcerations to be 1.69 percent in patients ages 65 to 95.4 Regardless of the underlying cause of the ulceration, conservative estimates report that more than 2 million people in the United States are currently being treated for chronic, non-healing wounds.
For many years, chronic wounds have been the subject of intense research in an effort to find methods to increase healing rates and decrease complications. Manipulation of the macroscopic and microscopic environments of wounds has been the key to success in healing both the acute and chronic wound. Wound treatments have ranged from the simple but effective wet-to-dry dressing to topical and systemic pharmacotherapy and biologic agents, including growth factors and skin substitutes or grafts.10
Then there is VAC Therapy (KCI). Well, understanding the usefulness of VAC therapy requires knowledge of the basic science behind a chronic wound. Chronic wounds typically represent a breakdown in the transition between the substrate and proliferative stages of wound healing.12 All stages of wound healing can actually be present in a single chronic wound. Many factors, such as vascular disease, diabetes, pressure, infection, environmental stress, age, nutrition, immune status and pharmacologic agents (both systemic and topical) have been reported to affect the wound environment adversely.13, 14

Using the subatmospheric pressure of VAC therapy can alter the wound environment by reducing bacterial load and chronic, often inflammatory, interstitial wound exudate; potentially increasing vascularity and cytokine expression; and physically contracting wound margins.15 All of these characteristics, particularly the removal of deleterious proteases, may help to convert a tattered wound bed into a red carpet of healthy granulation tissue so it may progress through the subsequent phases of wound healing.16