Improve the Accuracy of Blood Pressure Measurement of Atrial fibrillation patients using polynomial curve fitting

• Main Authors: Yi-Fang Luo, 羅宜方
• Other Authors: Liang-Yu Shyu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/39062275859288830409

碩士 === 中原大學 === 生物醫學工程研究所 === 102 === Atrial fibrillation (AF) is the most common sustained arrhythmia. According to previous studies, approximately 50% of the patients with AF are hypertensives and patients who are older than 65 years the incidence of AF is associated with increased age. Effective follow-up and blood pressure (BP) control is important for patients with AF. The irregularity of the pulse rhythm and variable stroke volume during AF make conventional auscultatory and oscillometric BP measurement inaccurate. In this study, we measured invasive and non-invasive oscillometric BP signals, simultaneously, while patients were conducting electrical ablation. The BP waveforms during AF and sinus rhythm (SR) were recorded. These BP data were processed and analyzed off-line in a personal computer. Additionally, using the invasive BP as reference, polynomial curve fitting were implemented to determine the most suitable characteristic ratio for non-invasive oscillometric BP measurement. Finally, the algorithm is realized in hardware devices, in order to improve the BP measurements accuracy in AF. Thirty six subjects were recruited in this study, and the mean age is 54.53 years. It was found that the average BPs in 20s intervals are compatible to one minute average. Thus, 20s averages were used to compare with invasive BP measurement to establish the characteristic ratios for non-invasive BP measurement using the minimum mean error. During SR, the characteristic ratios for systolic and diastolic blood pressure are 0.32 and 0.86, respectively. On the other hand, during AF, the characteristic ratios for systolic and diastolic blood pressure are 0.56 and 0.96, respectively. Lastly, we compared the BP readings of proposed system, Matlab, electric sphygmomanometer (WatchBP office AFIB, Microlife), and invasive measurements. During AF and SR, the t-test results indicate that there was no significant different in systolic, diastolic, mean BPs obtain from the proposed system and Matlab (P>0.05); and no significant difference between Matlab and invasive were founded (P>0.05). In the results of classification, using T index (0.895) to partition AF and SR, the proposed system is able to identify AF with a sensitivity of 100%, specificity of 24%, and accuracy of 59%.