Toward ischemia dynamics based medical diagnosis

For an arbitrary force impartment on tissue, the tissue color changes from red to white due to the decrease of arterial blood. The dynamics leading to (or recovering from) ischemia is a good index for evaluating the vitality of tissue. This paper discusses the ischemia dynamics by using a newly developed active sensing system composed of an air jet nozzle for imparting an air pulse to tissue and a high-speed camera for capturing the change of color of tissue with respect to time. Through experiments, we found that the ischemia dynamics is particularly characterized by the recovery phase where the time constant changes depending upon the local physical condition of tissue. We also showed a map on color changing rate conveniently utilized for quickly understanding the location of ischemia area which is a candidate replaced by regenerated tissue.