Experimental study of vascular reactivity in the fingertip: An infrared thermography method

Vascular reactivity (VR) test has been proved to be an effective method to predict the risk of future cardiovascular disease. A most common technique used to study VR is to analyze the hyperemic response after an ischemia through an arterial occlusion. Current techniques to monitor hyperemic response rely on monitoring blood flow parameters. As tissue temperature is directly impacted by blood flow, in this paper, an infrared thermograph method was used to investigate the variation of fingertip temperature during VR test. Subsequently, an image processing algorithm was developed to extract the temperature of special parts of the sequential thermal images. The measured results of temporal temperature variation clearly characterized the thermal state of a subject (vasoconstriction, vasodilation, and thermoneutral) as well as perfusion. Finally, a lumped parameter thermal model was employed to explain the experimental results.