Vacuum Assisted Wound Closure and Skin Stretching

Vacuum assisted Wound Closure (VAC) has been used in human medicine for difficult to treat wounds, pressure sores, chronic nonhealing wounds, diabetic associated wounds, and to secure skin grafts. the main advantage is the rapid accumulation of granulation tissue within the site and reduction of peri-wound edema.

The VAC is controlled, intermittent negative pressure applied to a wound bed to enhance healing. Veterinary patients become uncomfortable with cycling on and off the pressure, so we typically apply continuous negative pressure to the wound. Most bandage changes are done with sedation, so initial application of negative pressure does not seem to cause discomfort. Minimal secondary layers are required, so most patients are comfortable and quite mobile during VaC therapy. Commercially available, small pumps are used in human medicine and are now available in veterinary medicine, allowing patients to be walked with minimal changes to the system. the system is by definition closed and allows measurement of wound effusate and evaluation of gross character of the effusate. the fluid is removed from the wound bed, strike through of a normal padded bandage is avoided, and the VaC can be applied to many sites that are typically difficult to bandage. there may be added benefits of decreased bacterial num- bers under the wound bed, and the system is not proven but has been used by the author for decreasing dead space and debriding small sections of wound beds that are not ready for granulation.

The VAC likely works by applying mechanical forces / stress to the wound bed, removes and changes cytokine gradients, and decreases periwound edema, thereby increasing blood flow. there is a known increase in mitotic rate and increased tissue ingrowth dur- ing bone distraction using the ilizarov technique, and the VaC likely does the same. the altered wound fluid and cytokines may change Dna transcription, and decreasing peri- wound interstitial edema opens more capillaries and restores blood flow. Known effects include increased capillary blood velocity and volume as well as improved basement membrane stability. other effects include increased neutrophil numbers, increased angiogenesis, and increased tissue oxygenation. [...]