Simulating the Effect of Cuff Pressure on Brachial Artery for Calculating the Photoplethysmography(PPG) Singnal

Shiri, Farhad | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43958 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Firoozabadi, Bahar; Saeedi, Mohammad Saeed
  7. Abstract:
  8. One of the most important reasons of death in today’s world is the diseases related to cardiovascular system. Hypercholesterolemia is one of the most common forms of these diseases. There are a lot of experiments for diagnosing this disease, which are classified into two groups: invasive and noninvasive experiments. One of the well-known noninvasive experiments in this area is the photoplethysmography in which the changes of the photoplethysmography signal can reveal some valuable information about the cardiovascular system’s health.The objective of this study is to simulate the photoplethysmography experiment considering the clinical conditions of the experiment. In this work, the obtained photoplethysmography signal from this test is simulated while applying and after releasing the cuff while the reactive hyperemia phenomenon.
    This simulation is based on the 1D model which is proposed for the cardiovascular system. By having the 1D model, the effect of applying cuff, which associated with imposing pressure in the brachial artery, is simulated; and then the parameters related to the hydrodynamic changes of the signal at the downstream of cuff site are calculated during increasing the cuff pressure.These parameters are normalized values of pulse height, maximum and minimum slope and peak to peak interval(PPI) for each PPG signal. Next, reactive hyperemia phenomenon is simulated after releasing the cuff. In this phenomenon, because of the endothelial cells’ activation at the downstream of the cuff site, the mathematical model of the endothelial cells are used in the 1D model, and the changes in the PPG signal after the cuff is simulated. By studying the method of the variation of this signal in the clinical experiment for a group of healthy people and people with hypercholesterolemia disease , it has been clear that a parameter related to the PPG signal variation can be determined, so that this obtained parameter can discrete these two groups. Comparing the calculated parameter obtained from the signal variation from the model, it was found that the current model results are similar to the healthy group
  9. Keywords:
  10. One-Dimentional Modeling ; Finite Volume Method ; Photoplethysmography ; Cardiovascular System

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