Wright J W, Ridgway L E
Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio 78284-7836.
Am J Obstet Gynecol. 1990 Dec;163(6 Pt 1):1788-91. doi: 10.1016/0002-9378(90)90750-2.
The Poiseuille equation of fluid flow suggests that umbilical cord length and cord blood viscosity may affect resistance to flow and thus affect the systolic/diastolic ratio. In this prospective study of 40 uncomplicated term pregnancies, we sought to define the relationship of umbilical cord length and cord blood hematocrit level (as an index of viscosity) to the umbilical artery systolic/diastolic ratio. To focus on these factors, we minimized known sources of systolic/diastolic ratio variability and controlled for fetal heart rate. Linear regression revealed that fetal heart rate contributed 18% of the systolic/diastolic ratio variability. Conversely, umbilical cord length and cord blood hematocrit level were not related to umbilical artery systolic/diastolic ratio. We conclude that normal variations in cord blood hematocrit level and umbilical cord length do not significantly affect systolic/diastolic ratio.
泊肃叶流体流动方程表明，脐带长度和脐血粘度可能会影响血流阻力，进而影响收缩压/舒张压比值。在这项对40例无并发症足月妊娠的前瞻性研究中，我们试图确定脐带长度和脐血血细胞比容水平（作为粘度指标）与脐动脉收缩压/舒张压比值之间的关系。为了聚焦于这些因素，我们尽量减少已知的收缩压/舒张压比值变异性来源，并控制胎儿心率。线性回归显示，胎儿心率对收缩压/舒张压比值变异性的贡献为18%。相反，脐带长度和脐血血细胞比容水平与脐动脉收缩压/舒张压比值无关。我们得出结论，脐血血细胞比容水平和脐带长度的正常变化不会显著影响收缩压/舒张压比值。
