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In this study, we assessed the possibility of using portable laser Doppler flowmeters for determining the state of the blood microcirculatory system in upper and lower limbs of diabetic patients during the treatment course with intravenous α-lipoic acid infusions. A series of experimental studies were conducted in a cohort of ten inpatients with a confirmed diagnosis of type 2 diabetes mellitus. The state of peripheral blood flow of patients was assessed during 5 days on which they received daily doses of intravenous α-lipoic acid infusions. The values of the microcirculation and nutritive blood flow indices, as well as the bypass index, were assessed. To obtain a more extensive analysis, the patients' measurement results were compared with those of the control group composed of ten conditionally healthy volunteers of similar age. To determine changes in the regulatory mechanisms for the microcirculatory bed, we applied the amplitude-spectrum analysis of microvascular blood flow oscillations, using the mathematical tool of wavelet transform. We determined the changes in the index of blood microcirculation and the parameters of microcirculatory blood flow distribution into nutritive and shunt pathways, as well as the differences between these changes in upper and lower limbs. This approach is believed to become prospective as a pharmacotherapy efficacy assessment method based on responses of the system of blood microcirculation. [ABSTRACT FROM AUTHOR]

The article describes a multiparametric approach to the assessment of cutaneous microcirculation in dermatological patients (using the example of psoriasis patients). The multiparametric diagnostic approach consisted of three stages of successive measurements performed according to the methodology of laser speckle contrast imaging (LSCI), laser Doppler flowmetry (LDF), and videocapillaroscopy (VCS). Experimental studies on hemodynamic parameters were conducted in psoriatic patients with a course of conservative treatment. A combined application of optical noninvasive diagnostic methods allowed physicians to record changes taking place in the microcirculatory bed during treatment. It has been found that microcirculatory disorders observed before the start of treatment in the field of psoriatic plaques (an increase in the density of the capillary network, an increase in the indicator of microcirculation, nutritive blood flow and the amplitudes of myogenic and cardiac oscillations) were normalized due to the applied treatment, on which the assessment of its efficacy may be based. The suggested approach may be used for diagnosing microcirculatory disorders emerging in psoriasis in its preclinical stage, as well as for developing and testing new pharmacological means for its treatment. [ABSTRACT FROM AUTHOR]

Objective: Spectral analysis of laser Doppler flowmetry (LDF) signals has been widely used in studies of physiological vascular function regulation. An alternative to LDF is the laser speckle contrast imaging method (LSCI), which is based on the same physical principle. In contrast to LDF, LSCI provides non-scanning full-field imaging of a relatively wide skin area and offers high spatial and temporal resolutions, which allows visualization of microvascular structure. This circumstance, together with a large number of works which had shown the effectiveness of temporal LSCI analysis, gave impetus to experimental studies of the relation between LDF and LSCI used to monitor the temporal dynamics of blood flow. Methods: Continuous wavelet transform was applied to construct a time-frequency representation of a signal. Results: Analysis of 10 minute LDF and LSCI output signals recorded simultaneously revealed rather high correlation between oscillating components. It was demonstrated for the first time that the spectral energy of oscillations in the 0.01–2 Hz frequency range of temporal LSCI recordings carries the same information as the conventional LDF recordings and hence it reflects the same physiological vascular tone regulation mechanisms. Conclusion: The approach proposed can be used to investigate speckle pattern dynamics by LSCI in both normal and pathological conditions. Significance: The results of research on the influence of spatial binning and averaging on the spectral characteristics of perfusion monitored by LSCI are of considerable interest for the development of LSCI systems optimized to evaluate temporal dynamics. [ABSTRACT FROM AUTHOR]

Abstract Timely diagnostics of microcirculatory system abnormalities, which are the most severe diabetic complications, is one of the major problems facing modern health care. Functional abnormalities manifest themselves earlier than the structural ones, and therefore their assessment is the issue of primary importance. In this study Laser Doppler flowmetry, a noninvasive technique for the cutaneous blood flow monitoring, was utilized together with local temperature tests and wavelet analysis. The study of the blood flow in the microvascular bed of toes was carried out in the control group of 40 healthy subjects and in two groups of 17 type 1 and 23 type 2 diabetic patients. The local temperature tests demonstrated that the diabetic patients have impaired vasodilation in response to local heating. The tendency for impaired low frequency pulsations of the blood flow associated with endothelial and neurogenic activities in both diabetes groups was observed. Local thermal tests induced variations in perfusion and its spectral characteristics, which were different in the groups under study. In our opinion, the obtained preliminary results can be a basis for further research and provide a deeper understanding of pathological processes that drive microvascular abnormalities caused by diabetes mellitus. Highlights • Local thermal test affects averaged and spectral components of cutaneous blood flow. • Spectral pattern of blood flow oscillation caused by local heating differs in controls and DM. • DM is accompanied by impaired vasodilation and lower response of myogenic vascular tone. • The results give deeper insight into the development of vascular abnormalities in diabetes. [ABSTRACT FROM AUTHOR]

Optical techniques are one of the most promising non-invasive technologies for the diagnosis of medical conditions. This work is devoted to the current state of the optical non-invasive diagnostics (OND), especially about instrumentation as well as methodological and metrological provision for this technology. In some details Laser Doppler Flowmetry (LDF) and Fluorescence Spectroscopy (FS) diagnostics methods are considered. The main conclusion is that it is necessary to solve the problems of metrological support OND devices of these types. It is also important to develop a methodology based on diagnostic criteria obtained from a relationship between a number of OND methods and others.

The paper shows the possibility of using the laser Doppler flowmetry method for the assessment of system of blood microcirculation in the lower limbs of patients with diabetes mellitus. A series of experimental studies involving 76 patients with diabetes mellitus and 46 healthy volunteers was carried out. The state of peripheral blood flow was assessed during the local heating tests with different temperature regimes. The wavelet analysis of LDF-grams was used to evaluate the adaptive changes of microcirculation during the temperature tests. The data show that the proposed methodology in the form of heating tests and the use of the wavelet transform in the analysis of LDF-grams allows the evaluation of adaptation processes in the microcirculatory bed during thermal tests and the detection of the preclinical stage of trophic disorders. [ABSTRACT FROM AUTHOR]

We introduce a noninvasive diagnostic approach for functional monitoring of blood microflows in capillaries and thermoregulatory vessels within the skin. The measuring system is based on the combined use of laser Doppler flowmetry and skin contact thermometry. The obtained results suggest that monitoring of blood microcirculation during the occlusion, performed in conjunction with the skin temperature measurements in the thermally stabilized medium, has a great potential for quantitative assessment of angiospatic dysfunctions of the peripheral blood vessels. The indices of blood flow reserve and temperature response were measured and used as the primarily parameters of the functional diagnostics of the peripheral vessels of skin. Utilizing these parameters, a simple phenomenological model has been suggested to identify patients with angiospastic violations in the vascular system. [ABSTRACT FROM AUTHOR]