Key Insights On Using VAC Therapy For Post-Op Wound Management

Pages: 28 - 30
By Luis Leal, DPM

Vacuum Assisted Closure (VAC) is one of our greatest tools in managing large as well as deep wounds. It crosses multiple surgical disciplines and is applicable to virtually all anatomical sites. This technology has revolutionized limb salvage surgery and has prevented untold numbers of amputations. There is an exciting growth curve with the use of this technology. Surgeons can modify the technology to aid in the closure of a multitude of wound scenarios.

In the course of utilizing VAC therapy (KCI), one must be cognizant of adjacent tissue and protect it from the deleterious effects of negative pressure. This not only applies to intact tissue but also to split and full thickness grafts as well as adjacent tissue transfers, all of which are excellent indications for negative pressure to assist with graft adherence.

Our preferred method of protecting adjacent tissue or graft at the Wound and Limb Healing Institute is placing a xeroform gauze over the grafted tissue. One may apply the sponge directly to the xeroform without any damage to the underlying graft. It protects the graft or flap from being deformed by the sponge. The surgeon may also apply a portion of nanocrystalline silver dressing over the xeroform and subsequently use a sponge if he or she desires.

Managing multiple wounds on a single extremity often requires paying special care to adjacent intact tissue. In the following case, one also has to contend with an open partial first ray amputation in addition to the fasciotomy wounds to the leg, with the one medial wound extending into the plantar arch.

Large deep wounds may remain after multiple fasciotomies. These are generally bridged by an island of intact tissue. This island of tissue is critical to future reconstruction and eventual salvage of the limb. One may use more than one VAC therapy unit to achieve the desired results. However, by following safe, simple principles, the surgeon can use one unit to manage multiple wounds. This will, in effect, reduce the cost of therapy by using one less machine. It also simplifies nursing duties by monitoring only one device as opposed to two.

A Step-By-Step Guide To Managing Large Post-Op Wounds
One would begin by prepping and defatting the skin. Our preferred method is to use chlorahexadene, making sure none is introduced into the wound. This works exceptionally well, particularly in the obese individual and others with less than optimal, oily and irregular skin. Another benefit is that it does not discolor the skin and tones down some of the untoward odors that can accompany some of these applications. A more important effect of chlorhexadine is cleansing and disinfecting the periwound skin.

Place a xeroform gauze where you will use a bridge of foam to connect the wounds. This piece of xeroform needs to be slightly wider than the sponge you use for the bridge. Then one would place foam strips into the wounds. These foam strips need to be narrower than the wound in order to prevent maceration of the wound edges. The foam in the wound must be in full contact with the foam creating the bridge. Secure the foam bridges first with the supplied adhesive covering and then secure the foam in the wound.

One would then evaluate the entire construction and use one suction tube to complete the seal among the three wounds. Evaluate the site carefully for visible and audible signs of leakage. At the edge of the amputation site and the second toe in this presentation, use stoma paste to secure the seal and avoid the potential for loss of suction or injury to an already frail digit.

Stoma paste is an excellent adjunct in making difficult seals. This is particularly useful around digits at the distal aspect of a seal.

This area may be stressed into ischemic changes by overzealous application of the adhesive wrap. One would use the paste as an adjunct to the adhesive wrap. The surgeon should cleanse the paste thoroughly and remove it at each VAC therapy dressing change since it hardens, tends to discolor and may alter the appearance of healthy tissue.

The surgeon may also use stoma paste to secure seals in the presence of skinny wires from a circular fixation device. However, one must wait until the wire skin interface is intact, generally three to five days postoperatively.

How VAC Therapy Can Aid In Post-Amputation Revisions
Another salvage situation in which a more complex application of the VAC is required is during the management of a plantar flap from a revised transmetatarsal amputation or a more proximal foot amputation.

In this clinical scenario, one is dealing with delicate tissue at both the remaining stump site as well as the salvaged portion of the flap. The surgeon is attempting to coax the proximal amputation site and the flap to produce granulation tissue independent of each other.

One would use a typical black sponge over the remaining stump tissue while using a white sponge on the inner surface of the remaining flap. The goal here is to create granulation tissue on the inner aspect of the flap. Once there is adequate granulation on the inner portion of the flap, one can utilize negative pressure to adhere the flap to the stump. Use a white sponge on this more delicate tissue to avoid any chance of injury. Should there be exposed vessels, one may consider a white sponge as well in the early stages of managing the stump segment. Both sponges need to be touching during the process.

Once sufficient granulation has occurred on both sides, bring the flap cephalad and place a sponge over the protected flap to facilitate adherence of the flap to the amputation segment. The surgeon may accomplish this in the presence or absence of suturing.

Final Notes
At our institution, we commonly use VAC therapy on most revised amputations on the lower extremity. The major advantage is a hands-off approach to an already delicate segment of skin.

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