A Step-wise Discussion of Chemovac Assembly

Stepwise Technique: Lessons Learned

As one might imagine, the use of chemotherapeutic modalities is generally easy to perform. Topical applications and dressing traditional dressing modifications are, in many instances, technically unchanged from standard practice. Our experience with the application of chemovac dressings has underscored the importance of careful technique for optimal results. Many of these techniques are listed in the product instructions and have been previously discussed. We have found that they are useful in order to avoid the potential for complications from dressing adherence, leakage, durability, and subsequent maceration.

We therefore recommend that the wound area be thoroughly cleaned and dried between dressing changes. Adhesive tinctures such as benzoin or mastisol are useful in increasing the ability for the plastic dressing to form a tighter and more rigorous seal. It has also proven useful to ‘Window’ the wound edges with smaller strips of dressing seal in order to create more exact boundaries. This is helpful for wounds with irregular borders, the 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. This further prevents the potential for maceration of surrounding skin.

When the top cover is place over the sponge, it is important to do so in a manner which allows a flat and uniform contact across the sponge and skin. 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 being used. The dual port dressings such as ITI Sved units contain both ingress and egress interfaces, which are simply applied in the same manner as one would expect. However, when modifying or augmenting a standard VAC dressing with a make-shift ingress port, it is important to utilize IV tubing which can be inserted directly into the dressing.

For this, we recommend a minimal incision.

Additional seal or Tegaderm dressing material must then be used to seal this interface, and thus decrease leakage or loss of pressurization.

To our knowledge, the specific arrangement of these the ingress and egress ports is of little importance. By this, we have not experienced any notable effects from gravity or direction of flow. It appears that the chemotherapeutic agent is perfused through the sponge and is thus ‘delivered’ to the entire wound bed without prejudice. Therefore, merely spacing a reasonable difference between the two interfaces is more than sufficient at achieving satisfactory distribution.

At this point, negative pressure should be initiated. It is important to identify and eliminate any breaks in seal and loss of pressure. Once a satisfactory seal has been established, the chemotherapeutic input should be initiated. 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 avoidance of leakage and maceration, due to compromised dressing. Many hospital and care facilities possess automated IV infusion apparatuses. These devices allow for programmable infusion cycles to be administered. This is undoubtedly a convenience to care providers, but is not necessary to deliver infusion. A manual regulator is capable delivering a consistent and reliable infusion rate. Depending on several factors, typical rates of infusion range from 1-3 drops per 10 second interval.

One notable observation about the use of foam dressings with infusion ports, both modified as well as designed, is the increased reliance on patient compliance. This is seen, 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 satisfied. In this event, the discontinuation of chemovac therapy may need to be considered, in favor of standard dressings or NPWT. After all, wounds have been healed for many years, long before negative pressure dressings.

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