Portable laser Doppler flowmeter for microcirculation detection

Sampling volume assessment for wearable multimodal optical diagnostic device

The process and results of numerical Monte Carlo simulation of optical radiation propagation in laser Doppler flowmetry (LDF) and fluorescence spectroscopy (FS) channels of a wearable diagnostic multimodal device are described in this paper. To achieve the goal, a multilayer skin model with different parameters of blood and melanin content and different distances between sources and radiation receivers was designed. The changes in the sampling (diagnostic) volume depending on the anatomical features of the biological tissues, as well as on the technical parameters of the device were shown. Depending on the scattering media optical properties and the source-detector configuration of the device, the diagnostic volume can range from 2 to 7 mm3 . The obtained results allow the formation of specialized medical and technical requirements for wearable multimodal devices implementing LDF and FS channels.

Optical incoherent technique for noninvasive assessment of blood flow in tissues: Theoretical model and experimental study

Laser noninvasive methods for assessment of a tissue blood flow (BF), for example, the Laser Doppler Flowmetry (LDF), are well-known today. However, in such methods, low-frequency fluctuations (LFFs) in the registered optical signal caused by blood volume changes inside a tissue have not been studied in details until now. The aim of this study is to investigate the LFFs formation and to justify the LFFs-based diagnostic technique for cutaneous BF assessment. LFFs are theoretically described and experimentally shown in the input LDF signal inside the frequency range 0 to 10 Hz. They are substantiated as the basis of the new diagnostic method, in which BF is defined as the magnitude of blood volume changes in a tissue per unit time. The hand-made prototype of the promising diagnostic tool with light emitted diodes is used to validate the technique in experiments in vivo on 16 healthy volunteers in comparison with the LDF method. Experimental results show a good similarity of the recorded BF for both coherent and incoherent method. The proposed technique makes it possible the creation of inexpensive diagnostic equipment for assessment of cutaneous BF without using lasers and coherent light, completely and functionally comparable to LDF devices.

Methods and Limits for Micro Scale Blood Vessel Flow Imaging in Scattering Media by Optical Feedback Interferometry: Application to Human Skin

At the micrometric scale, vessels or skin capillaries network architecture can provide useful information for human health management. In this paper, from simulation to in vitro, we investigate some limits and interests of optical feedback interferometry (OFI) for blood flow imaging of skin vascularization. In order to analyze the tissue scattering effect on OFI performances, a series of skin-tissue simulating optical phantoms have been designed, fabricated and characterized. The horizontal (2D) and vertical (depth penetration) sensing resolution of the OFI sensor have been estimated. The experimental results that we present on this study are showing a very good accordance with theoretical models. In the case of a skin phantom of 0.5 mm depth with a scattering coefficient from 0 to 10.8 mm−1, the presented OFI system is able to distinguish a pair of micro fluidic channels (100 µm × 100 µm) spaced by 10 µm. Eventually, an in vivo test on human skin is presented and, for the first time using an OFI sensor, a 2D blood flow image of a vein located just beneath the skin is computed.

[Comorbid pathology of the cardiovascular system in young patients with relapsing-remitting multiple sclerosis]

AIM

To study the state of the cardiovascular system and peripheral microcirculation in young patients with relapsing-remitting multiple sclerosis (MS).

MATERIAL AND METHODS

The study included 45 MS patients (17 men and 28 women, age 28 [24; 32] years, disease duration 5.5 [2; 7] years). The control group included healthy controls (age 30 [25; 33] years). Neurological and cardiologic examinations included 24-hour Holter ECG monitoring and 24-hour blood pressure monitoring with determination of the daily arterial vascular stiffness, echocardiography, laser doppler flowmetry followed by an occlusive test to assess the state of microvasculation, levels of serum vascular cellular adhesion molecule-1 (VCAM-1).

RESULTS

In MS group, the results of 24-hour blood pressure monitoring showed that the variability of systolic blood pressure and diastolic blood pressure during daytime hours was reduced compared to the control group (p<0.026 and p<0.002, respectively). The indicators of daily arterial stiffness in MS group were significantly increased (p<0.001). According to the results of Holter ECG monitoring, no heart rhythm disorder was detected in both groups, except an increase in the number of supraventricular extrasystoles in MS patients compared to the control group (p<0.005). There were no between group differences in echocardiography indicators. The level of VCAM-1 was significantly increased in MS group compared to controls (p<0.001).

CONCLUSION

Young MS patients are at risk of cardiovascular diseases associated with the variability of blood pressure and indexes of daily arterial vascular stiffness.

Laser Doppler Imaging as a Measure of Female Sexual Arousal: Further Validation and Methodological Considerations

Laser Doppler imaging has recently been applied to the study of female sexual response, with promising results. The current study sought to provide further validation for its use in this capacity, as well as to examine the sexual psychophysiological concepts of genital non-response and return to baseline with this instrument. A sample of healthy heterosexual women without any sexual concerns (N = 24) participated in a single testing session design, which included self-report measures and genital imaging with the laser Doppler imager (LDI). During the imaging portion of the study, genital and subjective arousal data were collected while participants watched neutral and erotic film stimuli. The results support the validity of the LDI as a measure of female sexual arousal, and highlight its potential utility in research and clinical applications for sexual function and related difficulties.