Answer:
Vacuum-assisted closure is thought to remove chronic edema from the wound, leading to increased localized blood flow and enhanced formation of granulation tissue. Argenta et al. published a study which showed local blood flow levels increased fourfold in pig wounds where V.A.C was applied (125mmHg negative pressure). Lower wound bacterial counts and increased granulation tissue formation were noted. In a non-controlled, non-blinded human study, the same authors applied the technique in 300 wounds including 175 chronic ones. They found that almost all (296) responded favorably, either healing completely or allowing wound closure using grafting or flap techniques.