Friday, December 4, 2020

Wound Vac

 Q: In the initial phase of Negative Pressure Wound Therapy (NPWT) - Wound Vac - the perfusion is increased? 

A) True

B) False

Answer: B

It is beyond the scope of this website to describe in detail the working of Wound-Vac. The negative pressure system of wound-vac generates a pressure gradient between the wound and suction canister. This negative pressure transports the fluid from wound bed and interstitial space and reduces wound edema. It also causes cell/tissue modulation. The pressure applied in wound-vac is 5-10 mmHg. Also, the foam in wound-vac system contracts and draws the edges of the wound together. 

Wound-Vac has also many indirect effects of wound healing. The major indirect effects are 

  • Alterations in blood flow 
  •  Diminished inflammatory response 
  • Altered bacterial burden
  • Changes in wound biochemistry
It was thought that negative pressure increases the blood flow/perfusion. In reality, this pressure leads to a paradoxical decrease in perfusion and causes local ischemia in the early phases. This ischemia stimulates the release of growth factors and vasoactive agents, leading to increase granulation and healing.



1. Venturi ML, Attinger CE, Mesbahi AN, et al. Mechanisms and clinical applications of the vacuum-assisted closure (VAC) Device: a review. Am J Clin Dermatol 2005; 6:185. 

2. Kairinos N, Solomons M, Hudson DA. The paradox of negative pressure wound therapy--in vitro studies. J Plast Reconstr Aesthet Surg 2010; 63:174.

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