Wound Vacuum-assisted Closure (VAC) Therapy

VAC therapy may be indicated for treating various types of wounds, including chronic wounds that have not healed properly over time, such as foot ulcers from diabetes and pressure sores; or complicated acute wounds, such as crush injuries, burns, animal bites, and frostbite. These wounds are typically complex and carry a high infection risk, which requires more than a simple dressing; and may have already failed other wound care methods. Other examples of wounds that may benefit from VAC therapy include exudating wounds; surgery-related wounds, such as fasciotomy wounds; sternal or abdominal wound dehiscence (i.e., separation of the sternal or abdominal wall post-surgery); or skin graft fixation (i.e., securing of a graft to its underlying tissue to prevent detachment).  

Contraindications to wound VAC dressings include malignant wounds; fistulas; untreated osteomyelitis; and wounds with necrotic tissue, exposed nerves, arteries, anastomotic sites, or vital organs. Wound VAC dressings should additionally be avoided in individuals who are actively septic or are allergic to any of the wound VAC components. Lastly, VAC therapy is relatively contraindicated in individuals taking anticoagulants, who are actively bleeding, or have other conditions that impede coagulation.  

Before applying the VAC dressing, adequate debridement (i.e., wound cleaning from tissue damage and foreign materials) and hemostasis are achieved; the wound bed is washed with normal saline; and the surrounding skin is dried using sterile technique. Next, depending on the type of wound, a sterile foam, usually made from polyurethane, is adjusted to fit the wound's size and shape. This foam and a few centimeters of surrounding healthy tissue are then sealed with an adhesive drape to ensure a water- and air-tight seal. Once this is done, a small hole is cut in the adhesive drape to expose the underlying foam. Next, a tube with an adhesive disc at the terminus is applied and secured to the area of exposed foam, once again creating an air-tight seal underneath. This tube leads to a vacuum pump that operates on a pre-set, uniformly applied, negative pressure to remove fluid from the wound into a collection container. The machine can be set on various negative pressures and modalities, delivering continuous or intermittent suction, based on the characteristics of the wound (i.e., size, pain, exudation, etc.). For example, continuous high-pressure can be applied for large and highly exudative wounds, while low-pressure, intermittent settings can be utilized for chronic, painful wounds. Abrupt termination of VAC therapy is typically avoided to prevent a rebound phenomenon that could worsen the condition.  

This type of wound vacuum system is particularly helpful in preventing infections, by keeping the wound isolated, thereby creating a sterile condition for wound healing; maintaining a moist environment; and continuously removing drainage and fluid. In doing so, it reduces microbial load, as well as stimulates the formation of granulation tissue, which is less susceptible to infection. Furthermore, VAC therapy promotes blood flow, to aid in wound healing and removal of toxins and waste products. 

The risks of VAC therapy could include allergies to the adhesive tape, bleeding, infection, skin excoriation or necrosis, tissue adhesion to the foam, pain, restricted mobility, lack of compliance, or failure of the VAC system, due to power outage, inadequate seal, or blockage of the draining system. Inadequate compliance or sudden cessation of the treatment are additional risks that could result in a rebound phenomenon. Some signs that may require cessation of the VAC therapy include signs of adhesive allergy, increasing pain, excessive or active bleeding, or signs of infection such as fever, pus, or foul odor.  

Nonetheless, the VAC system has many benefits when used appropriately, including a reduced rate of dressing changes, treatment duration, hospital stay, and costs. Essentially, vacuum-assisted closure improves tissue perfusion by increasing blood flow to the wound and promoting angiogenesis; contracting the lesion by pulling the edges of the wound together, thus promoting the growth of new tissue; draining excess fluid and minimizing wound edema; and reducing bacterial load, further lowering the infection risk. Ultimately, all these features improve the likelihood of achieving primary wound closure and diminish the necessity for subsequent plastic surgeries.