A technique to visualize wound bed microcirculation and the acute effect of negative pressure

Although previous studies have proved that subatmospheric pressure in vacuum assisted closure therapy increased blood flow at the wound edge, no reports have presented data on blood flow in the wound bed. This study examined a technique that visualized microcirculation of the wound bed and estimated the acute effect of negative pressure. The superficial stratum of the mouse gluteal skin was microsurgically excised preserving the subdermal vascular plexus. The preserved vessels were visualized as the wound bed microcirculation using an intravital microscope-video-computer system. Three levels of negative pressure (-125 mmHg [n=12], -500 mmHg [n=12], 0 mmHg [n=8]) were applied to the wound. Our experimental model successfully and quantitatively visualized wound bed microcirculation under negative pressure application. A negative pressure of -125 mmHg significantly increased wound bed blood flow immediately after pressure application, maintained for 1 minute after pressure release, whereas in the -500 mmHg group blood flow decreased with time and reached a statistically significant level 5 minutes after pressure application. These findings reinforce the hypothesis that enhanced blood flow in the wound bed as well as at the wound edge may contribute to the beneficial effects of certain levels of negative pressure therapy for wound perfusion.