Author: Chi, Tianxi
Title: Skin blood flow oscillation studies using laser doppler flowmetry
Advisors: Liu, Y (ME)
Degree: Ph.D.
Year: 2019
Subject: Hong Kong Polytechnic University -- Dissertations
Blood flow -- Measurement
Blood -- Circulation -- Regulation
Skin -- Blood-vessels
Department: Department of Mechanical Engineering
Pages: iv, vi, 92 pages : color illustrations
Language: English
Abstract: Skin blood flow oscillation (SBO) may have considerable implication in the physiology and pathology of the arterial system. It has been well known that there are five frequency bands in skin blood flow oscillation, which are related to cardiac activity (0.6 -2 Hz), respiration (0.145 -0.6 Hz), myogenic activity (0.052 -0.145 Hz), sympathetic activity (0.021 -0.052 Hz) and endothelial activity (0.0095 -0.021 Hz), respectively. SBO exists all over the body, but shows different characteristics in different part of the body. The previous findings proved that the abnormal activity of skin blood oscillation on specific part of body could herald the coming of diseases such as hypertension, congestive heart failure and diabetes. Moreover, it also suggested that the skin blood flow oscillation might be related with the acupoints of acupuncture in Traditional Chinese Medicine (TCM) based on the literature reviews. It has been well accepted that the acupuncture could be effective in treating some diseases by stimulating certain acupoints. It have been found that acupuncturing a certain acupoint may change the skin blood flow oscillation activity on another acupoint of the body. We speculate that the skin blood flow oscillation on different acupoints may have intrinsic relationship. The previous studies only focused on the variation of amplitude of skin blood flow oscillation, and the spectral characteristics relationship have not been studied. Thus, the objective of my study is to investigate the spectral characteristics of each acupoint and the interrelationship among these acupoints, particularly on the background noise and signal to noise ratio (SNR). From mechanical engineering point of view, the flow oscillation should be induced by external force. The external driving force of SBO is from heartbeat, and we wonder if the variation of heartbeat induces the low frequency oscillation. To verify this assumption, we designed an experiment for simulating the blood flow through the single vessel. The infusion apparatus was regarded as the cardiac beating and the water as blood flow. During the experiment, we control the drip refer to the cardiac heart frequency, which around 1 Hz but varies with time, and use the LDF probe to measure the flow oscillation. In the absence of any biological response, we still detected the low frequency around 0.03 Hz by imitating the flow of blood through a signal vessel at the heart's pulse rate. We suggested that the variation of inlet flow (~ 1 Hz) may induce the lower frequency (0.03Hz) flow oscillation. Finally, some researcher have created the theoretical models for SBO based on the real biological data. They believed that analysis of these data along with computational modeling of vasomotion would help them to understand physiological mechanism in spectral characteristics. As their assumption, the created theoretical model could be considered as the healthy sample for comparing the real data from patient such as cerebrovascular or diabetes on spectral analysis, so that they could predict the severity of disease based on the spectral differences. Thus, we also believed that creating the theoretical models on different acupoints is an innovate method for deep understanding of TCM and essence of acupuncture. According to the performance of regularity activities shown differently in SBO at different acupoints on forearm, different theoretical models could be produced for assembling a total system.
Rights: All rights reserved
Access: open access

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