Evaluation of vascular endothelial function using the post-occlusion reactive hyperemia and its computer modeling

• Main Authors: Yong-Hong Pan, 潘永宏
• Other Authors: Jia-Jung Wang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/94611856695990719724

碩士 === 義守大學 === 生物醫學工程學系 === 104 === Vascular endothelial dysfunction has been shown to be an early indicator of atherosclerosis as well as a risk factor of cardiovascular disease. In the clinical trials, 52 subjects (Control group: N=38, Patient group: N=13) were recruited and asked to undergo a 5-minute occlusion of the brachial artery. The flow-mediated dilatation (FMD) was assessed by the air cuff oscillometry, the photo-plethysmography and the ultrasound technique, respectively. Furthermore, a three-segment circulatory network of arms was mathematically modeled on the basis of experimental data, and the proposed hemodynamic model was used to observe the change in pressure and blood flow in each segment during the reactive hyperemia period after 5-minute occlusion. The values of FMD induced by the 5-minute occlusion in Control group were found to be 8.1 ± 4.3%, 121.6 ± 34.4%, and 93.3 ± 48.6% using the Doppler ultrasound technique, cuff oscillometry and photo-plethysmography, respectively. With the cuff oscillometry, the mean FMD value was significantly greater in Control group than Patient group (121.5±34.4 vs 58.3±21.8%, p<0.001). Also, Control group had significantly larger maximum reaction time than that in Patient group (51.6±9.7 vs 24.3±6.1s, p<0.001). In applying the cuff oscillometry, Control group was found to have smaller oscillation amplitudes during the baseline and the reactive hyperemia than those in Patient group (1.44±0.75 vs 2.30±1.83 volts, p=0.002; 3.0±1.48 vs 3.58±2.73 volts, p=0.036). In the modeling, the time for the declining period was set to be twice that of the rising period. In the reactive hyperemia, the mean brachial arterial blood flow was modeled to be linearly increased from 38 ml/sec at the baseline to 76 ml/sec at the maximum response. Modeling results showed that the brachial arterial blood flow and blood pressure at the maximum hyperemia were 189 ml/sec and 172 mmHg, respectively. Furthermore, in combination of the change in the brachial arterial resistance from its baseline value to a half of, the brachial arterial blood flow and pressure at the maximum hyperemia were found to be 189 ml/sec and 147 mmHg, respectively. In conclusion, as compared with the Doppler ultrasound, the proposed air cuff oscillometry shows greater sensitivity and stability in assessing brachial arterial flow-mediated dilatation after 5-minute occlusion. Furthermore, the proposed arm-circulation model can be used to investigate the role of individual hemodynamic parameter and its effect on the blood pressure and flow in the circulation model.