A wound vac, also called negative pressure wound therapy (NPWT), helps wounds heal by applying controlled suction to the wound bed. This suction removes excess fluid, reduces swelling, improves blood flow, and stimulates the growth of healthy tissue.

Wound vac therapy is used for complex, chronic, and non-healing wounds because it actively changes the wound environment to support faster and more efficient healing.

Key Takeaways

A wound vac removes excess exudate from the wound, reduces edema, improves circulation, and promotes granulation tissue formation. It also helps contract wound edges and protects the wound from outside contamination. These combined effects create an optimal healing environment. Negative pressure wound therapy is commonly used for diabetic ulcers, pressure injuries, surgical wounds, and traumatic wounds.

What Is the Primary Function of a Wound Vac?

The primary function of a wound vac is to promote wound healing through controlled negative pressure. Unlike passive dressings, NPWT actively influences the wound environment.

According to StatPearls Publishing through the National Library of Medicine, negative pressure wound therapy is used to manage acute, chronic, and complex wounds by supporting granulation tissue formation and wound contraction.

What Does a Wound Vac Do to the Wound Bed?

A wound vac performs several important actions at the wound surface and below it.

Removes excess fluid

NPWT continuously pulls exudate from the wound into a collection canister. Excess fluid can increase tissue pressure, cause maceration, and delay healing. Removing this fluid helps stabilize the wound environment.

Reduces swelling

By evacuating interstitial fluid, the therapy decreases localized edema. Lower tissue pressure allows small blood vessels to function more effectively.

Improves blood flow

When swelling decreases, capillary blood flow improves. Enhanced circulation delivers oxygen and nutrients needed for tissue repair.

Stimulates new tissue growth (Microdeformation)

The mechanical forces created by suction stimulate cells in the wound bed. Research published in the International Wound Journal shows that this mechanical stress promotes fibroblast activity, collagen formation, angiogenesis, and granulation tissue development.

Granulation tissue forms the foundation for epithelialization, grafting, or surgical closure.

What Does a Wound Vac Do to Wound Edges?

Macrodeformation also called wound contraction, pulls the wound edges inward. This mechanical effect reduces wound size and helps bring tissue closer together, which can accelerate closure. This action is particularly beneficial for large, deep, or irregularly shaped wounds.

Does a Wound Vac Help Prevent Infection?

A wound vac does not replace antibiotics or surgical debridement. However, it helps manage factors that contribute to infection risk.

By removing exudate and sealing the wound with a semi-occlusive drape, NPWT reduces external contamination and helps control moisture balance. The Agency for Healthcare Research and Quality recognizes NPWT as an adjunctive therapy that supports wound bed preparation in appropriate patients.

What Does a Wound Vac Do for Chronic Wounds?

Chronic wounds often stall in the inflammatory phase of healing. A wound vac helps transition these wounds into the proliferative phase by:

Reducing chronic edema
Improving oxygen delivery
Stimulating cellular activity
Promoting granulation tissue development

These changes can restart the healing process in wounds that have not responded to standard dressings.

What Does a Wound Vac Do During Continuous Therapy?

Most wound vac systems use continuous suction and often default to a setting of –125 mmHg when black foam is used. ¹ Continuous therapy is recommended for the first 48 hours in all wounds to maintain a steady negative pressure, ensuring consistent fluid removal and mechanical stimulation. Following this 48-hour period, clinicians may wish to vary the settings based on individual patient needs and specific wound types. Intermittent therapy, where suction cycles on and off, may be considered for minimally exudating wounds or wounds with stalled progress.

What Does a Wound Vac Do?