Cath Lab Digest

A recent article by Sibbald¹ reviewed the findings of a Canadian consensus conference convened to address the use of Vacuum Assisted Closure® (V.A.C.® Therapy, KCI USA, San Antonio, Tex.) in wound management. Sibbald states the goal of the conference was to describe, “best practice statements that serve to guide treatment approaches and stimulate further study.”¹ Although Sibbald acknowledged the need for more prospective, randomized studies to guide the use of negative pressure wound therapy (NPWT) in chronic wounds, his review was limited by the fact that he only described the use of a single product rather than the concept of NPWT. Although V.A.C.® Therapy has achieved impressive results in appropriate wounds, the literature has failed to address other conceptualizations and incarnations of NPWT. This omission limits “thinking outside the box.” As everyone knows, not every duplication machine is a Xerox (Xerox Corporation, Stamford, Conn.) and not every flavored gelatin product is Jell-O (Kraft Foods, Northfield, Ill.). Therefore, the term V.A.C. should not be automatically synonymous with NPWT.

Presently, considerable legal parry and thrust has occurred as KCI seeks to maintain its proprietary hold on this modality. The general question arises: Is negative pressure (suction) proprietary? If wound care specialists are to push the limits in their endeavors to heal chronic wounds more efficiently and more cost effectively, the issues, concerns, and conditions that are not addressed by current technology must be identified and newer, more efficient technologies created. More specific questions regarding NPWT and, particularly, the V.A.C. are: 1) What are the limitations of the current incarnation? 2) Can these limitations be overcome using the currently available technology? 3) If not, could currently available technologies be used to overcome limitations? 4) If the technology is not yet available, how will it be developed?

Literature Review

NPWT as we know it. In 1997, Morykwas and Argenta^2-4 published three landmark articles regarding their experience with a “new method for wound control and treatment.”² A system was described where subatmospheric pressure^2,3 was applied through a closed system to an open wound for periods of 48 hours. Subatmospheric pressure was directed at the surface of the wound through an interface between the wound surface and a polyurethane sponge to allow for distribution of the negative pressure using either a constant or intermittent mode based on the clinical experience of the physician. From this technology, the V.A.C.® System evolved.

Negative pressure wound therapy is thought to promote wound healing through multiple actions — eg, removing exudate from wounds to help establish fluid balance,⁵ providing a moist wound environment,² and removing slough⁵; and potentially decreasing wound bacterial burden,² reducing edema and third-space fluids, increasing blood flow to the wound,^2,3,5 increasing growth factors, and promoting white cells and fibroblasts within the wound.⁶ Barker and Kaufman⁶ reported a 7-year experience with what was called “VAC pack” therapy in which the wound edges were attached to a circumferential plastic bag with small perforations that allowed drainage to escape. Suction drains were placed over the plastic to collect fluid via wall suction. This differs from current V.A.C.® Therapy in that negative pressure was not applied to the wound. The vacuum was used only as a method to collect fluid from the wound in a continuous manner.