Vacuum-assisted closure (VAC) is a noninvasive, active, closed wound management system that exposes the wound bed to local subatmospheric pressure.
Also referred to as negative-pressure wound therapy, VAC is used to stimulate granulation tissue formation, reduce interstitial edema and inflammatory cytokines, and improve circulation while maintaining a moist wound-healing environment.
Few published veterinary studies describe VAC wound care, although animal models were used to validate its efficacy in humans. In humans, VAC therapy is used extensively to treat chronic nonhealing wounds (eg, diabetic ulcers), burns, open fractures, abdominal compartment syndrome, and median sternotomy wounds.
Indications & Contraindications
Indications for VAC in animals include treatment of large, open, contaminated wounds; dehisced surgical wounds with or without exposed orthopedic implants or bones; degloving injuries and skin avulsions; chronic nonhealing wounds; and compartment syndrome (eg, abdominal/myofascial).
VAC wound care has also been used to prevent postoperative seroma or edema and enhance skin graft reepithelialization. With this therapy, wound size and volume are reduced, skin graft acceptance enhanced, response to antibiotic therapy improved, and duration of open wound management reduced (ultimately reducing hospitalization time and number of bandage changes).
VAC is most efficacious during the proliferative stage of wound healing but can be applied to almost any wound after appropriate debridement. To eliminate a potential nidus for bacterial growth and prevent proliferation of granulation tissue over necrotic tissue, which could result in delayed wound healing and abscess formation, devitalized tissue should be removed before VAC therapy is initiated.
VAC wound care is contraindicated when neoplasia is present at the wound site and should not be used as sole therapy for osteomyelitis. Severe hemorrhage may occur when VAC is used on wounds with exposed arteries or veins, as these vessel walls could erode. VAC should be used with caution in patients with coagulopathies.
Considerations & Complications
The most common pressure setting used in VAC wound care is continuous pressure of –125 mm Hg. When VAC is used to diminish postoperative edema or seroma formation on incision lines, pressure can be reduced to –50 to –75 mm Hg. Application of intermittent negative pressure can improve blood flow and granulation tissue formation but in humans has reportedly caused discomfort.
Frequency of bandage changes is determined by wound characteristics; VAC bandages are typically changed q48–72h, with more frequent changes early in the process to allow appropriate debridement. An airtight seal is essential to maintain continuous negative pressure and prevent wound desiccation.
Complications of VAC wound care are generally minor but can include loss of an airtight seal and local dermatitis associated with removal of the adhesive drape. If multiple VAC bandage changes are necessary, the foam can be removed by cutting the plastic drape and leaving a portion of the drape adhered to the skin. Doing so can decrease skin irritation and may eliminate the need for sedation.
More significant complications can occur if the dressing remains in place >3 to 4 days, as granulation tissue may grow into the open-cell polyurethane foam, requiring surgical debridement to remove foam particles.
What You Will Need
- Sterile water-based lubricant
- #40 clipper blade
- Sterile gloves
- Sterile surgical towels and instruments for surgical debridement
- Barrier film (Cavilon, 3M.com), adhesive spray (Vi-Drape, convatec.com), and/or adhesive stoma paste (Stomahesive, convatec.com)
- Sterile open-cell polyurethane foam (400–600-μm pore size)
- Sterile plastic adhesive drape
- T.R.A.C. Pad (KCIanimalhealth.com)
- 300-mL V.A.C. Freedom Canister (KCIanimalhealth.com)
- V.A.C. Freedom for Veterinary Use Therapy Unit (KCIanimalhealth.com)
- Spandex body suit, T-shirt, or soft padded bandage
- Elizabethan collar or basket muzzle
This is the third installment of The Essential Wound Care Series, which provides expert tips and techniques for managing both basic wound care and specific wound challenges.
Step-by-Step vacuum-assisted Wound Closure