Fetal Breathing Movement Monitoring System using Ultrasonic Doppler effect.

高精度定量监测胎动对评价胎儿健康状况具有重要意义。由于常规方法被设计用于监测胎儿心率，因此这些方法对于一般的胎儿健康监测来说并不令人满意。本研究将超声脉冲多普勒技术与胎儿体内微小位移测量技术相结合，建立了一种监测胎儿呼吸运动的新方法。在该方法中，超声脉冲被连续地发射到胎儿，并检测反射波。胎儿组织的微小位移是从超声波相位的微小变化测量的。该方法的特点是：1）监测胎儿横膈膜的微小位移，精度高; 2）从胎儿和母亲的复杂信号中只提取胎儿信号; 3）由于超声输出功率较低，对胎儿的安全性较高。在此基础上构建了一个新的监测系统。该系统可以在10个不同的点上监测内部小位移，每个点相距15 mm。该系统在东京大学医学部和Tukiji妇产科医院进行了评估，并获得了数十个样本记录。我们期望这种方法在不久的将来成为一种有价值的定量胎儿监护手段。

It is important to monitor the fetal movements quantitatively with high precision for evaluation of fetal well-being. Since conventional methods are designed for monitoring the fetal heart rate, these methods are not satisfactory for general fetal well-being monitoring. In this research, we developed a new method which can monitor the fetal breathing movements by using both ultrasonic pulsed Doppler technique and internal small displacement measurement method. In the method, the ultrasonic pulses are transmitted successively to the fetus and the reflecting waves are detected. The small displacement of the fetal tissue is measured from small change of the ultrasonic wave phase. The special features of the method are as follows ; 1) small displacement of fetal diaphragm is monitored with high precision, 2) only the fetal signal is extracted from complex signals of fetus and mother, 3) higher safety to the fetus because of lower ultrasonic output power. We constructed a new monitoring system based on these research results. This system can monitor internal small displacement at ten different points which are separated by 15 mm each. This system is evaluated at Faculty of Medicine, Tokyo University and Tukiji Obstetrics and Gynecology Hospital and more than several ten sample records are obtained. We expect that this kind of the method will be a valuable monitoring means for quantitative fetal monitoring in near future.