Assessment of Placental Blood Volume Flow and Function in IUGR Using a Transfer Function Model

摘要： 胎盘是胎儿所有营养和氧气输送的管道。因此，我们认为， 胎盘功能的评估对于理解和监测胎盘的生理状态是至关重要的。 发育中的胎儿所有的营养物质和氧气都是通过胎盘与胎盘之间的通讯到达胎儿的。 母亲和胎儿的血液循环。因此，胎盘功能的主要因素是血流和灌注。 在这方面，我们假设，一种新的方法来测量脐动脉和静脉流量， 产生关于胎盘功能状态的重要的新信息。由于标准频谱多普勒研究可以 检测与IUGR相关的血流异常，尽管通常在妊娠晚期，我们假设我们的新方法 将比目前的诊断技术更早地对胎盘功能的变化更敏感，包括 超声多普勒测量。我们表达这种乐观是因为我们将使用一个角度独立的， 流量剖面独立的体积流量测量方法，我们已经在其他设置中验证，使 同时测量脐动脉和静脉中的时间依赖性血流。这些将导致 直接转换为胎盘传递函数（PTF），这将是一种完全良性的方法，用于分析胎盘 在整个妊娠期间发挥作用。如果成功，我们的组合体积流量/传递函数方法可以快速 在标准诊断超声机上实施并进入临床使用。 最初，我们将使用体模研究来研究时间依赖性脐带血流是如何改变的 基于血管阻力和顺应性的受控变化，我们将使用这种时间依赖性流量 创建和验证体模的传递函数模型的信息。在幻影中，我们将有 完全控制流量、内部阻力/顺应性和压降。我们将能够看到 有效地，传递函数表示体模中的这些参数。一旦在幻影中得到证实， 使用经充分验证的宫内生长受限（IUGR）体内妊娠绵羊模型， 睾酮处理的羊，以测试如何以及流动和我们的传递函数模型预测胎盘的变化， IUGR。

Abstract: The placenta is the conduit through which all fetal nourishment and oxygen delivery passes. Therefore, assessment of placental function is critical to understanding and monitoring the physiological state of the developing fetus. All nutrients and oxygen get to the fetus through placental communications between the maternal and fetal blood circulations. Hence, major factors for placental function are blood flow and perfusion. In this regard, we hypothesize that a new method for measuring umbilical arterial and venous flows can yield significant, new information about placental functional status. Since standard spectral Doppler studies can detect flow abnormalities related to IUGR, albeit generally late in gestation, we hypothesize that our new methods will be more sensitive to changes in placental function earlier than the present diagnostic techniques, including ultrasound Doppler measurements. We are expressing this optimism because we will use an angle-independent, flow profile independent volume flow measurement method, that we have validated in other settings, to make time-dependent blood flow measurements in the umbilical arteries and vein simultaneously. These will lead directly to a placental transfer function (PTF), which would be a totally benign method for analyzing placental function throughout gestation. If successful, our combined volume flow/transfer function methods can be quickly implemented on standard diagnostic ultrasound machines and moved into clinical use. Initially, we will use phantom studies to investigate how time-dependent umbilical cord flow is altered based on controlled changes in vascular resistance and compliance, and we will use this time-dependent flow information to create and validate a transfer function model of the phantom. In the phantom, we will have complete control of the flows, internal resistance/compliance, and pressure drops. We will be able to see how effectively the transfer function represents these parameters in the phantom. Once proven in phantoms, we will use a well-validated in-vivo pregnant sheep model of intrauterine growth restriction (IUGR), gestational testosterone treated sheep, to test how well flow and our transfer function model predict placental changes in IUGR.