Schmidt K G, Di Tommaso M, Silverman N H, Rudolph A M
Division of Pediatric Cardiology, University of California, San Francisco 94143.
Am J Obstet Gynecol. 1991 Apr;164(4):1118-26. doi: 10.1016/0002-9378(91)90599-m.
Doppler velocity waveform analysis from descending aortic and umbilical artery signals was performed in 14 instrumented fetal lambs when umbilical blood flow was altered acutely. Blood flow was increased and reduced (by cord occlusion or placental embolization) and ranged 14% to 168% and 8% to 132% from baseline values in the descending aorta and the umbilical artery, respectively. When flow was severely reduced (less than 50% of baseline value), mean placental resistance increased almost fourfold and mean heart rate fell by 30% from baseline levels. There were only weak correlations between Doppler waveform indices and actual flow, which were usually not significantly different from the correlations between Doppler indices and actual heart rate. With both cord occlusion and placental embolization, significant changes of index values from baseline values were seen only when flow was severely reduced. We conclude that Doppler waveform analysis is not sensitive enough to detect acute mild to moderate reductions in placental flow. Increased index values with severely reduced flow may be explained in part by the concomitant fall in heart rate.
在14只植入监测仪器的胎羊中，当脐血流发生急性改变时，对降主动脉和脐动脉信号进行了多普勒速度波形分析。通过脐带闭塞或胎盘栓塞使血流增加和减少，降主动脉和脐动脉的血流分别在基线值的14%至168%和8%至132%范围内变化。当血流严重减少（低于基线值的50%）时，平均胎盘阻力增加近四倍，平均心率比基线水平下降30%。多普勒波形指标与实际血流之间只有微弱的相关性，这通常与多普勒指标和实际心率之间的相关性无显著差异。在脐带闭塞和胎盘栓塞两种情况下，只有当血流严重减少时，指标值才会出现与基线值的显著变化。我们得出结论，多普勒波形分析对于检测胎盘血流急性轻度至中度减少不够敏感。血流严重减少时指标值增加，部分原因可能是伴随的心率下降。
