Figure 2: The mechanism of VAC therapy: improvement of tissue perfusion, reduction of bacterial load and edema. Application of an abdominal VAC dressing. Coverage of the intra-abdominal content to prevent trauma through suction (A). The plastic layer is tugged in across the plastron (B). A VAC sponge is placed on top of this (C). The sponge is then covered with adhesive tape, with a track pad placed on top (D).
With the VAC technique, the open wound is converted into a controlled and temporarily closed environment. Animal studies have shown that VAC optimizes blood flow, decreases local edema, reduces bacteria levels, and removes excess fluids from the wound.2,8 (See Figure 3, above.) The cyclical application of sub-atmospheric pressure alters the cytoskeleton of the cells in the wound bed, triggering a cascade of intracellular signals that increases the rate of cell division and, thus, the formation of granulation tissue.9 This results in faster healing of the wounds than would have occurred with regular therapy; further, it significantly reduces hospitalization time and expenses.
Indications
VAC can be used on several types of wounds; however, before starting VAC therapy; adequate debridement for the formation of granulation tissue is essential.10 An overview of current clinical applications follows.
Chronic Wounds
The VAC system was originally designed to treat chronic wounds and to simplify the treatment of patients with chronic wounds both inside and outside the hospital.11 Around 10% of the general population will develop a chronic wound in the course of a lifetime; mortality resulting from these wounds amounts to 2.5%.12 VAC therapy has changed the clinical approach to and management of chronic wounds such as venous stasis ulcers, pressure ulcers, surgical dehisced wounds, arterial and diabetic ulcers, and a wide variety of other types of lingering wounds.12-15 Chronic wounds should be adequately debrided, either surgically or using another approach such as maggot debridement.16-18 This converts a chronic wound into a semi-acute wound. Such wounds respond better to VAC therapy than non-debrided wounds.11
Acute Wounds
VAC has become widely accepted in the treatment of large soft-tissue injuries with compromised tissue; it is also used for contaminated wounds, hematomas, and gunshot wounds. It has successfully been used in the treatment of extremities and orthopedic trauma and in treating degloving injuries and burns.19,21-25 (See Figure 4, p. 41.) When using VAC on traumatic injuries, nonviable tissue must be debrided, foreign bodies removed, and hemostasis obtained. Coverage of vital structures such as major vessels, viscera, and nerves by mobilization of local muscle or soft tissue is preferential. Wounds are then treated with VAC, and dressings are changed at appropriate intervals; if there is any suspicion of significant contamination, or if the patient develops signs of infection, adequate action, such as antibiotics or more dressing changes, must be taken.11
VAC therapy can also be used on a wide variety of surgical wounds and in treating surgical complications. It has successfully been used in sternal infections and mediastinitis, abdominal wall defects, enterocutaneous fistula, and perineal surgical wounds.11,26-35 The application of VAC in both chronic and acute wounds shows that it is a technique that facilitates wound management and wound healing for a wide variety of wound types.
Complications
When used within recommendations, complications resulting from VAC are infrequent.4 As the vacuum system device is more frequently adapted to multiple problems, however, the complication rate increases, probably due to co-morbidity and mortality.11 Localized superficial skin irritation is the most common complication reported in the literature.36 Further complications involve pain, infection, bleeding, and fluid depletion.4,12,35-37 Rare, severe complications, such as toxic shock syndrome, anaerobic sepsis, or thrombosis have been described as well.38-39(Also see M. Leijnen, MD, MSc, and colleagues, unpublished data, 2007.)