Development of Real Time Fetal Heart Rate Monitoring system

我们尝试开发胎儿手术和剖宫产时的胎儿心率监测系统。我们通过a /D转换器将产妇腹部引线的心电图信号采集到个人电脑上，并尝试实时测量胎儿心率。我们最终开发了一种软件，通过母体腹部导联和胸部导联获得的心电图信号来检测胎儿QRS。这里我们描述了我们算法的概要。我们应用差分滤波器来检测从母亲胸部引线获得的信号中的局部峰值。我们同样采用相同的筛选方法检测胎儿和母体qrs候选基因。然后我们挑选了胎儿QRS.4的候选基因。考虑到人工污染和每个R-R区间10%的变异性，我们尝试检测连续4个羊羊QRSs并计算胎儿心率。如果我们忽略了真正的feta QRS，计算R-R区间。所以我们做了一个额外的程序来避免这样的误解。然后，我们评估了我们的系统的可靠性在20名产妇择期剖宫产手术。结果表明，当胎儿QRS波幅大于10μV或大量肌电图伪影被污染时，算法能正确计算出胎儿心率。我们认为将心电图电极放置在子宫表面可以提高胎儿心率计算的准确性。

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.