多道胎儿监护仪的研制与胎儿心率信号的初步非线性动力学分析

【作者】 刘春霞；

【导师】 肖青；

【作者基本信息】 东北师范大学 ， 粒子物理与原子核物理， 2004， 硕士

【摘要】 监测胎儿心率及其变化，是了解胎儿在子宫内健康状况的最基本方法。基于传统的胎儿监护仪数据分析方法多为统计性原始定性分析，我们依据非线性动力学原理研制了多通道胎儿监护仪。首先，利用超声多普勒探头采集胎儿心音信号，对心音信号经过模拟电路和数字电路处理后，得到占空比不等的方波，将方波信号通过 PC-6360 模/数转换卡传递给计算机。同时，利用子宫收缩压力传感器采集孕妇子宫收缩信号，将子宫收缩信号经测量放大器放大后，通过 PC-6360 模/数转换卡传递给计算机.利用手动开关采集胎动信号，通过 PC-6360 模/数转换卡传递给计算机.我们采用 VB 高级语言编制了一个人机交互界面，建立了病例档案，并把计算得到的瞬时胎儿心率值传递给胎心监护仪的前面板显示电路，经 LED 数码管实现显示功能，并且在 VB 界面上实现胎儿瞬时心率信号、子宫收缩信号及胎动三路信号的实时数据及图像显示。同时界面可以实现数据及图形的重现功能，可以再现监测时的界面工作情况。当胎儿瞬时心率值异常时，能启动界面及监护仪前面板上的报警显示，实现报警功能。然后对信号进行统计分析、时域与频域分析、非线性动力学分析，为临床医生的诊断提供一种数值判断标准。 我们采集了 142 例孕期在 36 周至 41 周的胎儿心率信号，采集时间为 20-40 分钟左右。我们对 142 例心率信号进行了统计分析和时域与频域分析及非线性动力学分析，观察到大部分胎儿的平均心率集中在 145～155 次/分，其功率谱是一有尖峰的连续谱，说明心率信号不是简单的噪声.我们采用相空间重构技术构造了二维心率信号的吸引子，由图形可见其结构为奇怪吸引子，这可初步判定瞬时胎儿心率信号服从确定性动力学规律信号。更多还原

【Abstract】 It is convenient to diagnose the healthy state of fetus in the womb bymeans of examining the heart beat rate and heart beat rate variability. Themethods of traditional fetal monitor are mostly based on linear andstatistical qualitative on primary data analog, but the multichannel fetalmonitor based on non-linear dynamical principle comes forth under theendeavor of our group. At first, the heart beat rate signals are collected bythe ultrasonic Doppler heart beat probe, then they are treated with AnalogCircuit and Digital Circuit. We can get a square wave with differentoccupancy rate. Signals are inputted into computer through PC-6360Analog-to-Digital Converter. At the same time, the womb shrink signalsare collected by the womb shrink pressure sensor, then they are dealt withdifferential magnify and are inputted into computer through PC-6360Analog-to-Digital Converter. The quickening signals are also collected bymanual switch and are inputted into computer through PC-6360Analog-to-Digital Converter. In order to collect the signals, a controlinterface of Visual Basic is completed. This control interface canaccomplish real-time display and establish a file of case, at the same time,the numerical value of instantaneous heart beat rate is sent to displaycircuit of fetal monitor, the synchronous display realized by LED. Thecontrol interface can also realize the real-time data and plots display onthree signals of the instantaneous fetus heart beat rate, womb shrink andquickening, at the same time, the recurrence data and plots are realized,which can recur the instance of the measure working. If the instantaneousheart beat rate is out of the normal scope, the lamps of alarm will be started.Then we will do some statistical time and frequency and nonlinear analysis.We hope that we could approve a uniform criterion to the doctor by theanalysis of all kinds of cases. In this paper, signals of heart beat rate are collected from 142 healthyembryo, all of them are between 36 to 41 weeks old, the sampling time isabout 20 minutes. From the results of statistical,non-linear,time and 4<WP=5>frequency analysis, it can be found that most of the people’s heart beat ratecentralize at 145~155 times/min. It’s power spectrum is a continuousspectrum with a pinnacle, which shows that the heart beat rate signal isn’tsimple noise. It can be conclude from the results that the reconstruction inthe phase space of two –dimension instantaneous heart beat rate signal isstrange. It shows primarily that the heart beat rate signal isn’t simple noise,it is high dimensional chaos obeys certain dynamical law.更多还原