Abitbol M M, Monheit A G, Rochelson B L, Stern W, Blyakher L, Saraf V
Department of Obstetrics and Gynecology, University Hospital, State University of New York, Stony Brook, NY.
Am J Obstet Gynecol. 1989 Nov;161(5):1324-31. doi: 10.1016/0002-9378(89)90692-3.
A chronic sheep model for Doppler umbilical vascular analysis was developed, in which indwelling Doppler probes were used. These were designed with a fixed angle of insonation and implanted directly on the umbilical cord to register umbilical artery velocity waveforms. The fetuses in eight pregnant ewes underwent maternal aortic and umbilical cord constrictions producing serial blood flow reductions. Occlusion of the umbilical cord and maternal aorta caused distinctly different waveforms. Cord occlusion produced an immediate response with an elevated systolic/diastolic ratio and disappearance of diastolic velocity. Maternal aortic occlusion produced a delayed response with drops in both systolic and diastolic velocity; diastolic velocity never reached zero. Although systolic/diastolic ratios are believed to reflect placental resistance, the maintenance of the systolic/diastolic ratio with diminution of systolic velocity suggests declining fetal cardiac output as an additional factor. It is possible to differentiate uteroplacental from umbilicoplacental insufficiency by Doppler methods. With technologic improvements Doppler ultrasonography may allow better analysis of acute stressful conditions during human labor.
建立了一种用于多普勒脐血管分析的慢性绵羊模型，该模型使用了留置式多普勒探头。这些探头设计有固定的超声入射角，并直接植入脐带以记录脐动脉速度波形。八只怀孕母羊中的胎儿经历了母体主动脉和脐带收缩，导致血流连续减少。脐带和母体主动脉闭塞产生了明显不同的波形。脐带闭塞产生即时反应，收缩压/舒张压比值升高，舒张期速度消失。母体主动脉闭塞产生延迟反应，收缩期和舒张期速度均下降；舒张期速度从未降至零。尽管收缩压/舒张压比值被认为反映胎盘阻力，但随着收缩期速度降低而收缩压/舒张压比值仍维持不变，这表明胎儿心输出量下降是另一个因素。通过多普勒方法可以区分子宫胎盘功能不全和脐胎盘功能不全。随着技术的改进，多普勒超声检查可能有助于更好地分析人类分娩期间的急性应激情况。
