Analysis of time derivative of the temperature response of fingers on the brachial occlusion and its relationship with hemodynamic parameters

Abstract

Objective. The aim of the study was to analyze the time derivative of temperature response of finger phalanges to brachial occlusion and to establish the relationship between the parameters of temperature dynamics and hemodynamic parameters. Materials and methods. To analyze the response to the occlusion, the methods of dynamic thermography and photoplethysmography (PPG) were used. The parameters of the temperature reaction on occlusion in a group of 60 healthy subjects were analyzed. The Shitzer model was used to establish the relationship between temperature dynamics and peripheral hemodynamics. Results. Parameters describing the temperature response of the fingers on occlusion were introduced. It is shown that the time to reach the maximum of the temperature derivative during post-occlusion corresponds to the maximum of the volumetric blood flow. A coefficient of symmetry is proposed that characterizes the curve of the hemodynamic response of the extremity vessels to a sharp restoration of blood flow after removal of the occlusion. The parameters of temperature dynamics paralleled to the changes in hemodynamic parameters. Conclusions. To compare the results of temperature measurements and results of optical methods of blood flow estimation it is advisable to use not the temperature signal but its first derivative. The use of temperature parameters, expressed in degrees, creates the conditions for the development of a quantitative approach to the description of the hemodynamic response to occlusion. The results of the study contribute to the development of noninvasive methods of diagnosing endothelial dysfunction as a harbinger of atherosclerosis.