Effects of Vacuum-assisted Closure on Wound Microcirculation: An Experimental Study

Abstract

To study the mechanism through which vacuum-assisted closure (VAC) induces an increase in blood flow and reduces oedema on skin wounds. Thirty-two Japanese large-ear white rabbits were used. A round full-thickness skin defect (retaining the perichondrium), 2 cm in diameter, was created on each dorsal ear. The wound on the left ear was assigned to the experimental group, and the wound on the right ear to the control group. In the experimental group, the sterile foam dressing was trimmed to the appropriate size and geometry for the given wound and placed into the wound defect. The surface of the wound containing the foam dressing was covered with an adhesive drape to create an airtight seal. Afterwards, negative pressures of -5, -10, -15 and -20 kPa were exerted on the same wound, each lasting for 20 minutes, at intervals of 10 minutes. In the control group, the wound was treated with petrolatum gauze only. At different time points, the microcirculation microscope and image pattern analysis were used to observe the variation in wound microcirculation through a detective window. It was found that VAC promoted capillary blood flow velocity, increased capillary calibre and blood volume, stimulated endothelial proliferation and angiogenesis, narrowed endothelial spaces, and restored the integrity of the capillary basement membrane. By increasing capillary calibre and blood volume and by stimulating angiogenesis, VAC could improve blood circulation in wounds. By narrowing endothelial spaces and by restoring the integrity of capillary basement membranes, VAC could decrease the permeability of blood vessels and wound oedema.