What Does a Wound VAC Do? NPWT Mechanism Explained
What does a wound vac do?
The Quick Answer
**Wound VAC (Negative Pressure Wound Therapy)** applies controlled suction (-75 to -125 mmHg) through foam dressings to remove exudate, reduce edema, stimulate granulation tissue formation, and mechanically approximate wound edges. It accelerates healing by 30–50% in complex wounds by enhancing blood flow, reducing bacterial load, and promoting cellular proliferation through mechanotransduction—converting physical force into biochemical healing signals.
Why We Ask This
Patients view wound VACs as 'sucking out infection' while missing the nuanced cellular mechanisms—leading to premature discontinuation when drainage decreases (a positive sign of healing) or unrealistic expectations for simple wounds where standard dressings suffice.
The Practical Science
NPWT works through four mechanisms: 1) Fluid removal reducing edema and bacterial burden, 2) Microdeformation stimulating fibroblast proliferation, 3) Angiogenesis via VEGF upregulation, 4) Mechanical wound edge approximation. Studies show granulation tissue forms 63% faster under NPWT versus moist dressings in diabetic foot ulcers.
In Clinical Practice
A dehisced abdominal incision receives NPWT at -100 mmHg continuous—within 5 days, healthy granulation fills the wound bed allowing delayed primary closure versus 21+ days with standard packing, demonstrating how NPWT transforms non-healing wounds into closure candidates through accelerated tissue generation.
References & Context
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