Development of Real Time Fetal Heart Rate Monitoring system

我们尝试开发一种胎儿手术和剖宫产术中胎心监护系统。我们将孕妇腹部导联的心电信号通过A/D转换器输入微机，实现了对胎儿心率的真实的实时测量。最后，我们开发了软件，以检测胎儿QRS波从孕妇的心电信号获得的腹导联结合从胸导联获得的心电信号。在这里，我们描述了我们的算法的轮廓。1.我们应用差分滤波器来检测从母亲胸导联获得的信号中的局部峰值2。4.考虑到伪影污染和每个R-R间期10%的变异性，尝试检测连续4个胎儿QRS，并计算胎儿心率; 5.如果忽略胎儿真实QRS，计算R-R间期。因此，我们制定了一个额外的程序，以避免这种误解。然后，我们评估了我们的系统的可靠性，在20个产妇接受择期剖宫产。当胎儿QRS波振幅大于10μV或肌电伪影较大时，该算法能正确计算出胎儿心率。结论：将心电电极放置在子宫表面，可提高胎心率计算的准确性。

We tried to develop a monitoring system of the fetal heart rate during fetal surgery and cesarean section. We gathered the ECG signals from maternal abdominal leads to a personal computer via A/D converter and tried to measure the fetal heart rate in real time. We finally developed the software to detect the fetal QRS from the ECG signals obtained from maternal abdominal leads combined with the ECG signals obtained from chest leads. Here we described the outline of our algorithms.1.We applied the differential filter to detect the local peaks in the signals obtained from maternal chest leads2. We also applied the same filter and detected the candidates of fetal and maternal QRS.3.Then we picked up the candidates of fetal QRS.4.Considering artifacts contamination and 10% of variability in each R-R interval, we tried to detect consecutive four feta QRSs and calculated fetal heart rate.5.If we overlooked the true feta QRS, calculated R-R interval. So we made an additional routine to avoid such misinterpretation.Then we assessed the reliability of our system in twenty parturients undergoing elective cesarean section. We confirmed that our algorithm correctly calculated the fetal heart rate when the amplitude of fetal QRS was larger than 10μV or large electro-myograhic artifact were contaminated. We concluded that it would be better to place the ECG electrodes on the surface of the uterus to improve the accuracy of fetal heart rate calculation.