Brace R A
Department of Reproductive Medicine, School of Medicine, University of California, San Diego, La Jolla 92093.
Am J Obstet Gynecol. 1989 Feb;160(2):494-7. doi: 10.1016/0002-9378(89)90479-1.
The purpose of this study was to determine to what extent fetal thoracic duct lymph flow may be reduced by increases in fetal venous pressure. In pregnant sheep the fetal left thoracic lymph duct was catheterized at the base of the neck and this catheter was connected to a jugular-vein catheter so the lymph could spontaneously return to the fetal circulation. At 5 days after catheter implantation in nine unanesthetized fetuses at 133 +/- 1 (SE) days' gestation, lymph flow was measured by disconnecting the lymphatic catheter from that in the jugular vein and varying outflow pressure of the lymphatic catheter independent of venous pressure. Whenever outflow pressure was negative, lymph flow was independent of outflow pressure and averaged 0.66 +/- 0.05 ml/min. When outflow pressure of the left thoracic duct was increased above zero, lymph flow decreased linearly with outflow pressure and flow stopped at an outflow pressure of 11.5 +/- 0.6 mm Hg. At a normal venous pressure of 3 mm Hg, the lymph-flow sensitivity to venous pressure was such that a 1 mm Hg rise in venous pressure reduced lymph flow by 12.7% +/- 1.2%. Thus it appears that fetal lymph flow is very sensitive to outflow pressure and only moderate elevations in venous pressure potentially may lead to fetal edema.
本研究的目的是确定胎儿静脉压升高会在多大程度上降低胎儿胸导管淋巴液流量。在怀孕的绵羊中，胎儿的左胸导管在颈部基部被插入导管，该导管与颈静脉导管相连，以便淋巴液能够自发回流到胎儿循环系统。在妊娠133±1（标准误）天的9只未麻醉胎儿中，在导管植入5天后，通过将淋巴管导管与颈静脉导管断开连接并独立于静脉压改变淋巴管导管的流出压力来测量淋巴液流量。只要流出压力为负，淋巴液流量就与流出压力无关，平均为0.66±0.05毫升/分钟。当左胸导管的流出压力升高到零以上时，淋巴液流量随流出压力呈线性下降，在流出压力为11.5±0.6毫米汞柱时流量停止。在正常静脉压为3毫米汞柱时，淋巴液流量对静脉压的敏感性使得静脉压每升高1毫米汞柱，淋巴液流量就减少12.7%±1.2%。因此，似乎胎儿淋巴液流量对流出压力非常敏感，只有静脉压的适度升高才可能导致胎儿水肿。
