Development of Non-invasive and Ambulatory System for the Monitoring of Instantaneous Cardiovascular Hemodynamic Parameters along with Autonomic Activities

点击翻译按钮获取中文摘要

In order to assess on-line autonomic regulation of cardiovascular system during daily activities, a non-invasive and ambulatory system has been successfully developed, which can automatically monitor instantaneous digital or radial systolic (SBP), mean (MBP), and diastolic blood pressure (DBP), stroke volume (SV), heart rate (HR), cardiac output (CO=SV・HR), and total peripheral circulatory resistance (TPR=MBP/CO). Principle of the instantaneous blood pressure measurement is based on the volume-compensation method using the photoplethysmographic vascular unloading technique with a newly designed partially pressurization cuff, while that of the CO measurement based on the electrical admittance (or impedance) cardiography with newly proposed spot electrodes alignment.As to accuracy of the system, the performance of the instantaneous radial blood pressure measurement method was evaluated with the direct blood pressure measurement using 9 healthy subjects. The results of the Bland-Altman an … More alysis of the SBP and DBP measurements were -0.46±4.1 and 0.63±3.3mmHg (mean±1.96SD, (accuracy±precision)), respectively. The performances of the admittance cardiography with the spot electrodes (the current source electrode pair : behind of the ears-right side of the waist, the detection electrode pair : manubrium-xiphoid process (the both ends of the sternum)) were also evaluated with the dye-dilution cardiac output measurement. Appling to the Kubicek's method of the impedance (or admittance) cardiography, the assumption of the homogeneity of the current distribution of the thorax between these spat electrodes was confirmed by the 24 (4 x 6) spot electrodes thorax impedance mapping system. The result of the Bland-Altman analysis of the CO measurements was 0.2±2.0l/min (mean±1.96SD).Using this system, the autonomic regulation analysis was conducted by the spectral method of the FFT and MEM (Maximum Entropy Method). The high frequency component (HF : 0.15-0.5Hz) of the IBI (inter-beat interval) has been recognized as the index of the vagal nerve activity. The low frequency component (LF : 0.04-0.12Hz) of the TPR was proposed as the solely index of the sympathetic nerve activity. However, these indexes had been failed to describe sudden changes of the human activities due to long range of data requirements, i.e. 64-128 points. We concluded that further development of the instantaneous autonomic regulation analysis should be desired to evaluate in detail human activities against various stress conditions during daily life. Less