Thompson R S, Trudinger B J, Cook C M
Ultrasound Med Biol. 1985 Sep-Oct;11(5):707-18. doi: 10.1016/0301-5629(85)90104-8.
Doppler ultrasound waveforms from the fetal umbilical artery were analyzed by a new quantitative technique. Normal pregnancy and cases of fetal growth failure were considered. Data from the spectrum analyzer were dumped to a microcomputer, the velocity waveforms calculated and a representative waveform obtained by ensemble averaging. This curve was then fitted by a 4-parameter analytic function. We introduce R, the relative flow rate index, which measures the ratio of the average flow rate before the systolic peak to the average rate during the remainder of the cardiac cycle. In cases of fetal growth failure this ratio was significantly greater than in normal pregnancy. Other new quantities defined are the normalized systolic decay time index and the constant flow ratio. The AB ratio was also calculated. Fetal growth failure has been associated with raised placental resistance. We suggest that the fetus can initially compensate for this by increasing cardiac contractility. This can be seen by interpreting the R and AB values together. Our analysis technique enables the waveform to be efficiently described, and provides useful diagnostic information about placental function and fetal wellbeing.
采用一种新的定量技术分析胎儿脐动脉的多普勒超声波形。研究对象包括正常妊娠和胎儿生长受限病例。频谱分析仪的数据被转存到一台微型计算机中，计算速度波形，并通过总体平均获得代表性波形。然后用一个四参数解析函数拟合该曲线。我们引入相对流速指数R，它测量收缩期峰值前的平均流速与心动周期其余时间的平均流速之比。在胎儿生长受限的病例中，这个比值显著高于正常妊娠。定义的其他新参数是标准化收缩期衰减时间指数和恒定流速比。还计算了AB比值。胎儿生长受限与胎盘阻力升高有关。我们认为，胎儿最初可以通过增加心肌收缩力来对此进行代偿。通过综合解读R值和AB值可以看出这一点。我们的分析技术能够有效地描述波形，并提供有关胎盘功能和胎儿健康状况的有用诊断信息。
