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目的：经胎羊腹主动脉注射微球的方法阻塞胎盘，建立胎儿窘迫的动物模型，研究脐动脉搏动指数（ＰＩ）的血液动力学特点。材料与方法：健康妊娠绵羊（湖羊）８头，于妊娠１１６～１２５天行宫腔内胎儿手术，胎羊股动脉插管，顶端达胎羊腹主动脉水平，脐动脉置电磁流量计探头，检测胎儿腹主动脉血压和脐动脉血流，手术后予以补液、抗炎、抗凝、补充羊水等处理。经胎儿腹主动脉导管注射微球阻塞胎盘（每１５ｍｉｎ一次）。用快速傅里叶转换的方法把血压和血流波形的时域信号转换为输入阻抗的频域图谱，计算脐动脉阻力（Ｒ）、阻抗（Ｚ）和搏动指数（ＰＩ）。结果：微球注射次数与脐动脉阻力的对数之间有明显的相关性（ｒ＝０．６５７９，Ｐ＜０．００１），与脐动脉阻抗之间无明显的相关性（Ｐ＞０．０５），与脐动脉ＰＩ的对数之间有明显的相关性（ｒ＝０．９２２０，Ｐ＜０．００１）。ＰＩ与Ｒ／Ｚ比值有明显的相关性（ｒ＝０．９７４３，Ｐ＜０．００１），明显优于ＰＩ与阻力的相关性（ｒ＝０．９０９１，Ｐ＜０．００１）。结论：脐动脉的ＰＩ不仅反映了阻力的变化，而且间接受阻抗的影响；ＰＩ直接反映了Ｒ／Ｚ比值。
OBJECTIVE: To establish a animal model of fetal distress by blocking the placenta by injection of microspheres into abdominal aorta and to study the hemodynamic characteristics of umbilical artery pulsatility index (PI). MATERIALS AND METHODS: Eight healthy pregnant sheep (Hu sheep) were enrolled in this study. Intrauterine fetal surgery, intrauterine fetal femoral artery catheterization, sheep aorta level were performed on the 116th to 125th day of gestation. The umbilical arterial magnetic flowmeter probe, Detection of fetal abdominal aortic blood pressure and umbilical artery blood flow after surgery to rehydration, anti-inflammatory, anticoagulation, amniotic fluid supplementation and other treatment. The fetus through the abdominal aortic catheter microspheres obstruction of the placenta (once every 15min). The fast Fourier transform method was used to convert the time-domain signals of blood pressure and blood flow waveform into the frequency-domain maps of input impedance, and calculate the resistance (R), impedance (Z) and pulsatility index (PI) of umbilical artery. RESULTS: There was a significant correlation between the number of microspheres injected and the logarithm of umbilical artery resistance (r = 0.6579, P <0.001), but no significant correlation with umbilical artery impedance (P> 0.05). 05), and the logarithm of umbilical artery PI was significantly correlated (r = 0.9220, P <0.001). There was a significant correlation between PI and R / Z ratio (r = 0.9743, P <0.001), which was significantly better than the correlation between PI and resistance (r = 0.9091, P <0.001). Conclusion: The PI of umbilical artery not only reflects the change of resistance, but also indirectly influences the impedance. PI directly reflects the ratio of R / Z.