Abstract
Three basic studies, two of which form the basis for the treatment regiment, are
described. The initial study was a basic dose-response experiment that examined
the local vascular response to increasing levels of applied vacuum. Full thickness
defects were created on the dorsal midline of anesthetized animals, and needle probes
from a laser Doppler were inserted into the tissues. The foam dressing was placed
into the defect and the site sealed with a thin film dressing. After establishing the
baseline flux, vacuum was applied in a stepwise manner using 25mm mercury
(Hg) increments, returning to atmospheric pressure (0mm Hg vacuum) between each
step. The response was a bell-shaped curve with the maximum increase in flux
occurred at 125mm Hg-applied vacuum, with flux increasing approximately 400
over baseline levels (4). The flux then decreased and actually was less than baseline
with applied vacuum levels greater than 300mm Hg. The decrease may be due to one
of two mechanisms: stretching of the small vessels when the tissue is deformed from
the applied vacuum, thus decreasing the diameter of the vessels; or the physical compression of the small vessels due to bulk movement of the tissue.