Symonds E M
J Reprod Med. 1987 Jul;32(7):509-12.
Digital filtering techniques can be applied to the recovery of the fetal electrocardiogram (ECG) from noise, using optimized digital filters matched to the frequency characteristics of the waveform. By forming a linear model of the fetal ECG, it is possible to measure time constants and characteristics on a real-time basis. The technique provides a powerful tool for the detection of subtle changes in the ECG, but the interpretation of these changes is critical to the application of the technique in fetal monitoring. Shifts in the ST segment and changes in T wave configuration are late indicators of fetal asphyxia, whereas the earliest indicators of stress are shortening of the PR interval and inversion of the normal positive relationship between the PR and RR intervals. The method appears to substantially enhance our ability to predict fetal stress at an early stage.
数字滤波技术可用于从噪声中恢复胎儿心电图（ECG），通过使用与波形频率特性相匹配的优化数字滤波器来实现。通过构建胎儿心电图的线性模型，可以实时测量时间常数和特征。该技术为检测心电图中的细微变化提供了强大工具，但这些变化的解读对于该技术在胎儿监测中的应用至关重要。ST段移位和T波形态改变是胎儿窒息的晚期指标，而应激的最早指标是PR间期缩短以及PR与RR间期之间正常正向关系的倒置。该方法似乎极大地增强了我们在早期预测胎儿应激的能力。
