Construction of Programmable Long-Term Measurement and Recording System for Biological Signals

为了研究心血管信号的波动和预测病理事件的发生，需要一个系统来实现在白天以外的较长时间内的稳定测量和记录。在本研究中，我们构建了这样一个系统。主要研究成果如下：1.构建的便携式生物信号长期记录系统具有存储容量高达192MB、低功耗、测量方式可编程等优点。第二个系统是在第一个系统的基础上增加的，增加了数据传输接口，并增加了监测系统内部状态的指示器。2.为了排除心电中包含的基线的缓慢波动，组成了多个数字陷波滤波器，并开发了专用的R波和T波提取算法。3.为了进一步分析心电数据，提出了一种基于非平稳谱分析的新方法来阐明自主神经活动之间的平衡变化规律。并实现了双谱分析。为了刻画心血管系统的状态依赖性，估计了心血管变量之间的脉冲响应。新提出了心血管动力学之间的距离度量来定量区分状态依赖属性。4.在自由运动环境下，包括睡眠和清醒状态在内的忠实测量和记录被证实保持了长达32小时。受试者声称在佩戴该系统时没有不舒服的感觉。该系统适用于睡眠呼吸暂停患者在允许自由活动的情况下，用电容式麦克风代替加速度传感器来监测气管声音。该应用表明该系统对患者的可用性也是令人满意的。

In order to investigate fluctuations in the cardiovascular signals and to predict occurrences of pathological events, a system is essential which realizes stable measurement and recording for a long period beyond the day length. In this study, such a system is constructed. The results are summarized as follows.1.The constructed portable long-term recording system for biological signals has the following merits including a large scale memory up to 192MB,low power consumption realized by CMOS-based circuits, programmable measurement modes. The 2nd system is additionally developed based on the experiences of the 1st one, where the interface for data transfer is enhanced and the indicators for monitoring the internal states of the system is newly equipped.2.The multiple digital notch filter is composed for excluding slow fluctuations of the baseline contained in ECG,and the special-purpose algorithms for extracting R and T waves are also developed.3.For further analyzes of EGG data, a novel method is developed to clarify a transition rule of the balance between the autonomic activities based on the nonstationary spectral analysis. The bispectral analysis is also implemented. Impulse responses between cardiovascular variables are estimated for chracterizing the state-dependency of the cardiovascular system. The distance measure between cardiovascular dynamics are newly proposed to quantitatively differentiate the state-dependent properties.4.Under the free-moving environment, faithful measurement and recording are confirmed to be maintained up to 32 hours including sleep and waking states. The subjects claim no uncomfortable feelings while wearing the system. The system is applied to the sleep apnea patient under allowed to move freely, where a condenser microphone is equipped instead of the acceleration sensor for monitoring tracheal sounds. This application shows satisfactory availability of the system for patients as well.