Home health monitoring for elderly : Development of a health monitoring device for bathing

设计了一种不受约束的心电图仪和心率监测器，用于在浴缸中记录心电测量值。该仪器由模拟部分和数字部分组成。在模拟部分，从放置在浴缸内的电极获得的心电信号被放大。电极由不锈钢制成，大小为104*74*0.5 mm，包括吸收海绵盖。工作电极放置在距浴缸长壁底部20 cm、靠近浸泡躯干的位置，参比电极放置在距侧壁底部5 cm、靠近脚趾位置的位置。在系统的数字部分，根据每个心电脉冲的R-R间期计算心率，并将计算的数据存储在随机存取存储器中。这些存储数据通过RS 232C接口传输到个人计算机并进行分析。浴缸心电图得到的心率与体表心电图得到的心率一致。浴缸心电图的频率特征随浴缸尺寸和水的电导率而变化。使用这种仪器，心率测量可以容易和非侵入性地获得，但对心电信号的解释需要非常小心。因此，这种监护仪可以用作家庭健康心率监测仪。对于家庭保健，当其他家庭成员也使用监测设备时，需要进行个人身份识别。在床上，个人身份识别很容易，因为大多数受试者都使用自己的床。在浴缸中，提出了使用心电波形进行个人身份识别[7，8]。获得一个心动周期的心电波形，采用Daubechies-4为母小波的小波变换对心电数据进行约简，并引入三层神经网络对家庭成员中的每个对象进行识别。

An unconstrained electrocardiograph (ECG) and heart rate monitor was designed to record ECG measurements in the bathtub. The apparatus consisted of analog and digital parts. In the analog part, electrocardiographic signals obtained from electrodes placed inside the bathtub were amplified. The electrodes were made of stainless steel and were 104*74*0.5 mm in size including the absorbent sponge covers. Working electrodes were placed 20 cm from the bottom of the long bathtub wall, close to the position of the immersed trunk, and a reference electrode was placed 5 cm from the bottom of the side wall close to the toe position. In the digital part of the system the heart rate was calculated from the R-R interval of each ECG pulse and the calculated data were stored in a random access memory. These store data were transferred to a personal computer through an RS 232C interface and analyzed. The heart rates obtained from the bathtub ECG agreed with those obtained from a body surface ECG.The frequency characteristics of the bathtub ECG varied with the bathtub dimensions and the electrical conductivity of the water. Using this apparatus, heart rate measurement can be obtained easily and noninvasively, but interpretation of the electrocardiographic signal requires great care. This monitor could thus be used as a home health heart rate monitor.For home health care, personal identification was required when other family members also used monitoring devices. In bed personal identification was easy because most subjects use their own bed. In the bathtub, personal identification using an ECG waveform was proposed [7,8]. The ECG waveform of one cardiac cycle was obtained and wavelet transform in which the mother wavelet was Daubechies-4 was applied to reduce the ECG data and a three-layr neural network was introduced to identify each subject among the family members.