Assessment of blood microcirculation and oxidative metabolism of biological tissue in the limb at changing its position by methods of laser Doppler flowmetry and fluorescence spectroscopy
Authors: Skripal An. V. , Verkhov D. G. , Al-Badri Farkad , Mashkov K. V. , Usanov A. D. , Sagaidachny A. A. , Zaletov I. S. , Klochkov V. A. 
Published: January 2025

Introduction. Diagnostics of blood circulation in skin microvessels and oxidative metabolism of biological tissue allows predicting the presence of microcirculatory disorders in the body, assessing their severity and monitoring therapy. The use of a functional test related to the change in the position of the entire human body in space is a well-known method for studying the functions of the autonomic nervous system and diagnosing cardiovascular diseases.Purpose. To study a set of parameters characterizing oxidative metabolism and dynamics of blood microcirculation in the finger during a sequence of tests with the change in the position of the upper limb using fluorescence spectroscopy and laser Doppler flowmetry.Materials and Methods. The study was conducted on a group of volunteers consisting of 10 people aged 21–40 years. The LAZMA PF device (Russia), implementing the methods of laser Doppler flowmetry and fluorescence spectroscopy, was placed on the pad of the middle finger. Each volunteer’s microcirculation parameters were measured in two arm positions: «at heart level» and with the limb vertically raised in the «up» position. Blood flow oscillations were continuously measured during all stages: three times in two positions.Results. A change in the limb position from the «at heart level» to «up» state leads to a decrease in the average values of microcirculation indices by 12 perfusion units (p. u.) and oxidative metabolism by 7 relative units (r. u.) with a simultaneous increase in the NADH coenzyme by 3 r. u., i.e. there is a unidirectional change in the microcirculation and oxidative metabolism parameters and an oppositely directed change of the NADH coenzyme values. According to the results of NADH coenzyme measurements, based on the analysis of statistical data, a statistically significant difference was found between the «at heart level» and «up» arm positions. This difference was not revealed only in the first cycle of the study, the reliability of p was greater than 0.05, between the arm positions 1–2, when the arm was «at heart level» and then raised «up». It was also found that with each new measurement cycle, the probability value of p for NADH indicators steadily decreased with a change in the arm position, at a significance level of p<0.05. The probability value of p became statistically significant starting from the second cycle of the study. Based on the results of oxidative metabolism indicator measurements, it was found that the probability value of p had a statistical significance of p<0.05 at each change of arm position in each cycle.Conclusion. The studies have shown that in order to obtain reliable information about the results of the limb position test, it is not enough to perform one-time measurements of the microcirculation indicator or the oxidative metabolism of biological tissue using laser Doppler flowmetry. The position of the limb and its change leads to significant changes in microcirculation and oxidative metabolism indicators, which should be taken into account when conducting medical and physiological studies