Study on the autonomic regulation analysis of cardiovascular system using non-invasive and ambulatory system for monitoring instantaneous blood pressure and cardiac interbeat interval

为了分析日常生活活动中心血管系统的自主调节，设计了一种新型的无创动态监测系统(160x140x45 mm，700gf)，该系统可以逐拍地从心电波形中自动监测收缩压(SBP)/平均压(MBP)/舒张压(DBP)、脉搏间期(P-P)、搏间间期(IBI)和呼吸间期(REP)。血压测量的原理是基于我们以前提出的血管卸载体积补偿法。6个时间序列数据经必要的信号处理后，用单片机配以交互软件存储在IC存储卡中，共存储约70万拍的数据。在监测之后，这些存储的数据被再现，在CRT监视器上显示，并使用传统的个人计算机执行必要的分析。考虑人体体位变化对心血管变量影响的生理学意义考虑…在开发本系统的同时，还设计了一种便携式仪器，用于长期动态监测体位变化。这一测量是基于这样一个事实，即几乎所有日常生活中的人体姿势都可以从胸部、大腿和小腿三个部分的重力方向对应的角度来估计。该仪器(58x94x25 mm，130g)可以使用放置在三个部分上的电磁倾斜仪将这些角度存储在CMOS RAM(2MB)中，并且如果在实验情况下重新布线，可以很容易地与上述系统一起使用。在本研究中，通过(I)通过计算机扫描逐次SBP和PP(或IBI)值获得的压力感受器-心脏反射敏感度(BRS)，(Ii)通过SBP和IBI数据的功率和交叉频谱计算的传递函数，以及(Iii)使用最大熵方法对SBP和IBI数据进行频谱分析，来评估心血管系统的自主调节功能，以年轻(20~24岁，男性)健康受试者为研究对象，收集日常生活活动中的数据，分为9项体力活动；仰卧(休息)、坐着(休息)、椅子上的办公桌工作、站立、站立时不动地工作、步行、上下楼梯和骑自行车锻炼。结果表明，随着体力活动的增加，IBI数据在0.15-0.5赫兹高频范围内的BRS值和功率谱密度显著降低，提示迷走神经活动会受到体力活动的抑制。在0.04-0.12赫兹的低频范围和高频范围内，当相干系数较高时，传递函数的增益也证实了这一现象。但在低频范围内IBP和SBP的功率谱密度与体力活动无显著相关性，提示SBP和IBP的低频功率可能受迷走神经和交感神经活动对体力活动的调节，因此不能作为仅评价交感神经活动的重要指标。通过这些发现，我们认为应该进一步开发能够同时监测血压和心输出量(从而监测外周血管阻力)的动态系统，以详细评估日常生活中的交感神经活动。较少

In order to analyze autonomic regulation of cardiovascular system during daily life activities, a non-invasive and ambulatory system (160x140x45mm, 700gf) has been newly designed, which can automatically monitor systolic (SBP) /mean (MBP) /diastolic pressure (DBP), pulse interval (P-P), inter-beat interval (IBI) and respiration interval (ReP) from ECG waveform on a beat-by-beat basis. Principle of blood pressure measurement is based on the volume-compensation method using vascular unloading, previously proposed by us. 6 time-series data are recorded in an IC memory card after necessary signal processings using a single-chip microcomputer with an interactive software, altogether about 700,000 beats of data being stored. After the monitoring, these stored data are reproduced, displayd on a CRT monitor, and performed necessary analyzes using a conventional personal computer. Taking physiological importance of the effect of human posture changes on the cardiovascular variables into conside … More ration, a portable instrument for long-term ambulatory monitoring of the posture chnges has been also designed in parallel with the development of the present system. This measurement is based on the fact that almost all human postures in daily life can be estimated from the angles corresponding to the gravitational direction in three portions ; chest, thigh and lower leg. The instrument (58x94x25mm, 130g) can store these angles in a CMOS RAM (2MB) using electro-magnetic inclinometers placed on the three portions, and easily be used together with the above system if rewuired under an experimental situation.In this study, autonomic regulatory function of the cardiovascular system was assessed by (i) baroreceptor-cardiac reflex sensitivity (BRS) obtained by computerised scanning of beat-by-beat SBP and PP (or IBI) values, (ii) transfer function calculated by power and cross spectra of SBP and IBI data, and (iii) spectral analysis of SBP and IBI data using a naximum entropy method, which were performed by a personal computer-based system.Using young (20-24 years old, male) healthy subjects, data were collected under daily life activities and categorized into 9 physical activities ; supine (rest), siting (rest), desk work on a chair, standing, working during standing without movement, walking, up and down the stairs, and bicycle exercise. It is demonstrated that the BRS values and power spectral density of IBI data over high frequency (HF) range of 0.15-0.5 Hz were significantly reduced following the increase in the physical activities, indicating that vagal nerve activity would be depressed by the increase in the physical activities. This phenomenon was also confirmed by the gain of the transfer function at higher values of the coherence over low frequency (LF) range of 0.04-0.12 Hz and HF range. However, power spectral densities of IBI and SBP data over LF range showed no significant correlation with the physical activities, indicating that LF powers of both SBP and IBI might be modulated by the vagal and sympathetic nerve activity against the physical activities and thus not be a significant index to assess only the sympathetic activity. Through these findings, we conclude that further development of ambulatory system capable of monitoring both blood pressure and cardiac output (and thus peripheral vascular resistance) should be desired to evaluate in detail the sympathetic activity during daily life. Less