Can 'Chemovac' Dressings Be A Valuable Addition To Wound Care?
- David G. Armstrong DPM MD PhD
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Editor's note: This blog entry is co-authored by Nicholas Giovinco, BS.
As one might imagine, the use of chemotherapeutic modalities is generally easy. Topical applications and traditional dressing modifications are, in many instances, technically unchanged from standard practice.
Our experience with the application of “chemovac” dressings (combining chemotherapeutic dressings with negative pressure wound therapy (NPWT)).
We recommend thoroughly cleaning and drying the wound area between dressing changes. Adhesive tinctures such as benzoin or Mastisol (Allegro Medical) are useful in increasing the ability for the plastic dressing to form a tighter and more rigorous seal. We have also found it useful to ”window” the wound edges with smaller strips of dressing seal in order to create more exact boundaries (see Figure 1). This is helpful for wounds with irregular borders, when there is a need for bridging two or more wound beds, and to prevent excessive contact between viable surrounding skin with the foam sponge.
In addition, we recommend precise trimming of the foam sponge with shears or even a scalpel blade (see Figure 2). This further prevents the potential for maceration of surrounding skin.
When placing the top cover over the sponge, it is important to do so in a manner that allows a flat and uniform contact across the sponge and skin (see Figure 3). By preventing wrinkles, tracks or “cigar rolls,” one can minimize leakage and non-uniform distribution of negative pressure.
The next step will depend on the type of negative pressure device and dressing one is using. The dual port dressings, such as SVED units (Innovative Therapies), contain both ingress and egress interfaces that are applied in the same manner as one would expect. However, when modifying or augmenting a standard VAC therapy (KCI) dressing with a makeshift ingress port, it is important to utilize IV tubing, which one can insert directly into the dressing (see Figure 4). For this, we recommend a minimal incision (see Figure 5).
One must then use an additional seal or Tegaderm (3M) dressing material to seal this interface (see Figure 6). Doing so decreases the risks of leakage or a loss of pressurization.
To our knowledge, the specific arrangement of these ingress and egress ports is of little importance. Specifically, we have not experienced any notable effects from gravity or direction of flow. It appears that the chemotherapeutic agent perfuses through the sponge and is accordingly “delivered” to the entire wound bed without prejudice. Therefore, merely spacing a reasonable difference between the two interfaces is more than sufficient to achieve satisfactory distribution (see Figure 7).
At this point, the clinician may initiate negative pressure wound therapy (NPWT). It is important to identify and eliminate any breaks in seals and loss of pressure. After establishing a satisfactory seal, initiate the chemotherapeutic input. By initiating the negative pressure component prior to chemotherapeutic input, one can ensure a consistent and predictable rate of infusion. In our experience, most dressing configurations merit this process as a “best practice” in the avoidance of leakage and maceration due to a compromised dressing.
Many hospital and care facilities possess automated IV infusion apparatuses. These devices allow one to administer programmable infusion cycles. This is undoubtedly a convenience to care providers but is not necessary to deliver infusion. A manual regulator is capable of delivering a consistent and reliable infusion rate. Depending on several factors, typical rates of infusion range from one to three drops per 10-second interval (see Figure 8).
One notable observation about the use of foam dressings with infusion ports is the increased reliance on patient adherence. This is true of both foam dressings designed with infusion ports and those dressings modified to have ports. This occurs more so with the use of such chemovac devices outside of hospital and specialized care facilities where strict adherence to therapeutic instructions and foam dressing application is not always evident. In this event, one may need to consider discontinuing chemovac therapy in favor of standard dressings or NPWT.
After all, clinicians have been healing wounds long before negative pressure dressings came along.
Editor's note: This blog has been adapted with permission. It originally appeared at www.diabeticfootonline.blogspot.com.