Laser Doppler Flowmetry and Laser Speckle Contrast Imaging are applied usually for assessment of parameters of the cutaneous blood flow during thermoregulation. Alternatively, this work explores the feasibility of blood pulsation imaging under incoherent green illumination for measuring the response of human body on local thermal impact. The proposed technique allows assessment of the cutaneous blood flow changes during thermoregulation simultaneously in different areas of the body. The preliminary experiments show that the blood pulsation amplitude (BPA) is sufficiently reliable index, which could characterize the relative change of the cutaneous blood flow similarly to the parameter measured with the Laser Doppler Flowmetry technique. It is shown that BPA grows up proportionally to the skin temperature increase in the preliminary cooled finger, whilst it is in the steady state in another finger having the constant temperature. The rate of BPA increase is individual characteristic of a subject, which could serve as a parameter of the subject's vasomotor reactivity on the temperature changes. High quality of visualized distribution of blood pulsations, good repeatability of the BPA, and revealed dependencies of its response on the skin-temperature change offer the prospect for development new system of studying microcirculation.

The possibility of using a new contactless method of imaging photoplethysmography to assess thermoregulatory vasodilatation of blood vessels was studied. Perfusion reaction in a region of the outer forearm in response to local heating up to 41 ± 1 °C was monitored in six volunteers aged 39-52 years using a video recording of the study area, synchronized with an electrocardiogram, and subsequent correlation processing of the data obtained. It was shown that the change in perfusion during local heating has a biphasic type and is due to the response of the nervous system mediated by the axon reflex in the first phase of vasodilation and the synthesis of nitric oxide in endothelial cells in the second phase of vasodilation. It was revealed that the multiple increase in perfusion in the first phase of heating depends both on the initial temperature of the skin and on the difference in its heating temperature. It was found that for a significant development of a vascular response to hyperthermia associated with the activation of endothelial function, heating of tissues for more than 15 minutes is necessary. It was shown that the method of imaging photoplethysmography reliably reflects the work of the mechanisms of regulation of peripheral vascular resistance which is of great prognostic value for the detection of primary signs of cardiovascular diseases.

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Исследована возможность применения метода визуализации пульсаций крови для изучения процесса термической релаксации живых тканей человека. Экспериментально показано, что амплитуда пульсаций крови в ткани (Blood Pulsation Amplitude-BPA) зависит от термического воздействия на нее; установлено, что процесс охлаждения тканей приводит к падению BPA, а процесс нагревания тканей сопровождается ее ростом. Скорость увеличения BPA является индивидуальной характеристикой субъекта, которая может служить параметром вазомоторной реактивности сосудов при изменении температуры.