The study of the fetal heart rates changes in hypoxemia by spectral analysis

本研究的目的是利用功率谱分析胎儿窘迫时胎儿心率变异性的变化。1998年，我们实验研究了反复脐带闭合条件下羔羊胎儿心率谱结构的变化。已知功率谱由两个主要频率区构成，一个是低频区（约0.1 Hz），其变化与胎羊交感神经系统相关，另一个是高频区（约0.3-0.5 Hz），其变化与副交感神经系统部分相关。本年度我们发现低氧血症胎儿1小时内低频区模式呈下降趋势。正常情况下高频区与低频区变化相对应，低氧血症时高频区与低频区变化不同。特别是在严重低氧血症时，频率区往往只在高频区出现短暂性增加。

The purposes of this study were to clarify the change of the fetal heart rate variability by using power spectral analysis in fetal distress. In 1998 we studied experimentally the change of fetal heart rate spectral structure of lamb under repeated umbilical cord occlusions. It was known that the power spectrum is constructed with two main frequency areas, one is low frequency area (about 0.1 Hz), which changes correlating with the sympathetic nervous system in fetal lamb, another is high frequency area (about 0.3-0.5 Hz), which is partially correlating with parasympathetic nervous system. In this year we found that the mode of the low frequency area during 1 hour is decreasing in fetal hypoxemia. And the high frequency area, which changes corresponding with the low frequency area in normal condition, changed differently than the low frequency area in hypoxemia. Especially the transient increase of frequency area was frequently noticed only in high frequency area in severe hypoxemia.