Analysis of fetal autonomic nerve activity by a power spectrum of heart beat-to-beat intervals and its application for clinical fetal monitoring

胎心监护已被广泛应用于早期发现胎儿死亡在目前的临床设置，胎儿心率描记的解释有时是不确定的，特别是当胎儿早产。与成人心率相比，胎儿心率波动的频率分析一直不成功。我们成功地利用无创多普勒超声测量胎儿心跳间期。在0.1周/拍左右观察到一个双峰，主要显示胎儿交感神经活动，在动物实验中，用胎羊作实验，这个峰被称为低频区（LFA），与胎儿状况有很好的相关性。也就是说，随着胎儿酸中毒，它的体积减小。在临床应用中，该系统可以很好地与胎儿血气值相关联，在不久的将来，该系统将成为传统胎心监护的替代方案。

Fetal heart rate monitoring has been widely used for early detection of fetal demise in current clinical settings.Interpretation of fetal heart rate tracing is sometimes indecisive, especially when the fetus is premature. In contrast to adult heart rates, frequency analysis of fetal heart rate fluctuation has been unsuccessful. We succeeded in measurement of beat-to-beat intervals of fetus using non-invasive Doppler ultrasound. A dual peak was observed in around 0.1 cycle/beat range, which mainly shows the sympathetic nerve activity of the fetus.In animal experiments, using fetal sheep, this peak designated "Low Frequency Area, LFA" is well correlated with the fetal condition. Namely, it decreases in size as fetus becomes acidosis. In clinical settings, this system may well be correlated with fetal blood gas values.In near future, this system will become alternative fetal monitoring to conventional fetal heart rate tracing.