Distribution of blood flow oscillation across the Doppler shift evaluated by the proposed approach with local pressure test.

<p>A step-wise increase in local pressure is known to cause a&nbsp;gradual change in the parameters of capillary blood flow in the<br> upper layers of the skin, and can also affect the measurement&nbsp;results of various optical methods. The impact of&nbsp;the procedure has several subsequent effects, such as mechanical compression of vessels, and neurological and metabolic&nbsp;compensating mechanisms like pressure-induced vasodilation,&nbsp;which maintain the homeostasis of the skin during moderate&nbsp;levels of external pressure and tissue hypoxia. To&nbsp;examine how those effects are translated to the blood flow&nbsp;registering in different ranges of the Doppler spectra, we&nbsp;have developed a 3D-printed pressure distribution tool&nbsp;compatible with the developed sensor which was used, and&nbsp;equipped with a set of weights.&nbsp;</p> <p>During the main series of measurements, the weights were&nbsp;placed into the PDT in a step-wise manner to achieve the<br> following values of pressure applied: 10 mmHg, 30 mmHg,&nbsp;90 mmHg, 150 mmHg, 210 mmHg. At the end of the procedure, the load was reduced back to 30 mmHg. Experiments&nbsp;were conducted with the participation of 7 healthy volunteers with 10 min LDF recording for each step. To estimate&nbsp;the prominence of the observed effects and substantiate the&nbsp;measuring routing, several preliminary experiments were also&nbsp;conducted where the set of values of pressure was applied with&nbsp;a step-wise increase and then decrease with about 2 min of&nbsp;LDF recordings for each step.</p> <p>Published in IEEE Transactions on Biomedical Engineering &quot;Diagnosis of skin vascular complications revealed by time-frequency analysis and laser Doppler spectrum decomposition&quot;, Zherebtsov et al.</p>