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Science Behind the Therapy

Wound Healing Begins at the Cellular Level

Understanding the Science of V.A.C. Therapy

With more than 918 peer-reviewed articles, the clinical and economic benefits of V.A.C.® (Vacuum Assisted Closure®) Therapy, also known as NPWT (Negative Pressure Wound Therapy) are widely known: faster20 and more effective5 than gauze11,14, leading to improved patient's Quality of Life1 and cost - effectiveness3. However, it is equally important to understand how NPWT, namely V.A.C. Therapy works deep inside the wound to achieve the superior clinical outcomes. The following sections describe how V.A.C. Therapy promotes cellular wound healing and how its unique mechanisms of action differentiate it from other Negative Pressure Wound Therapy (NPWT) devices.

What Makes Up the V.A.C. Therapy System

Three Critical Components, One Unique Integrated System

The V.A.C. Therapy System is comprised of three essential components that actively work together to help induce celluwound healing through promotion of granulation tissue formation2,12,13.


V.A.C. Therapy System Illustration



  1. V.A.C. Therapy Unit Provides intermittent and continuous therapy with integrated patient safety features.
  2. SensaT.R.A.C. Technology Regulates pressure at the wound site to provide accurate delivery of prescribed therapy settings
  3. V.A.C. GranuFoam Dressings Help induce the necessary mechanisms to promote granulation tissue formation

How V.A.C. Therapy Works at the Cellular Level Subhead

The Science Behind V.A.C. Therapy: Macrostrain and Microstrain

Under negative pressure, V.A.C. Therapy with proprietary V.A.C. GranuFoam Dressings applies both mechanical and biological forces to the wound to create an environment that promotes wound healing. These forces are known as macrostrain and microstrain.





Macrostrain is the visible stretch that occurs when negative pressure contracts the foam.


  • Draws wound edges together
  • Provides direct and complete wound bed contact
  • Evenly distributes negative pressure
  • Removes exudate and infectious materials





Microstrain is the microdeformation at the cellular level, which leads to cell stretch.


  • Reduces edema
  • Promotes perfusion
  • Increases cellular proliferation and migration
  • Promotes granulation tissue formation

Using V.A.C. Therapy with V.A.C. GranuFoam Dressings results in both macrostrain11,16,18 and microstrain11,16,18 for advanced wound healing.

Revised illustration that shows the “circles” that depict the mechanisms of macrostrain and microstrain

Watch a video of how V.A.C. Therapy works on the cellular level through macrostrain and microstrain. 







V.A.C. Therapy Mechanisms of Action – Transcription (RTF, 28.7 KB)

How V.A.C. Therapy Removes Barriers to Wound Healing

V.A.C. Therapy Mechanisms of Action

V.A.C. Therapy provides a closed, moist environment that promotes wound healing through the following mechanisms:

Wound Healing Barrier V.A.C. Therapy Mechanism
Excessive bacterial burden Removes infectious materials
Inadequate protection against infection Provides protected wound healing environment
Excess exudate Removes exudate
Excess edema (interstitial fluid) Reduces edema (interstitial fluid)
Absence of moisture Provides a moist wound healing environment
Lack of adequate blood flow Promotes perfusion
Lack of cellular activity Promotes cellular migration and proliferation during granulation tissue formation

SensaT.R.A.C. Technology

V.A.C. Therapy uses SensaT.R.A.C.™ (Therapeutic Regulated Accurate Care) to:

  • Monitor and maintain target pressure at the wound site for consistent therapy delivery
  • Reduce tubing blocks and false alarms through enhanced fluid dynamics
  • Enable Smart Alarms™ for enhanced patient safety
  • Provide easier and efficient V.A.C. Dressing applications
  • Enhance patient comfort


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