Rudolph C D, Meyers R L, Paulick R P, Rudolph A M
Cardiovascular Research Institute, University of California, San Francisco 94143.
Pediatr Res. 1991 Apr;29(4 Pt 1):347-52. doi: 10.1203/00006450-199104000-00004.
The ductus venosus allows highly oxygenated blood returning from the umbilical-placental circulation to bypass the liver, and is believed thereby to facilitate preferential distribution of this blood to the fetal brain and heart. To examine this hypothesis, we developed a model that allows acute obstruction of the ductus venosus in chronically catheterized fetal lambs. In seven fetal lambs, a Swann-Ganz catheter was inserted into the inferior vena cava and the balloon tip advanced into the ductus venosus. Control measurements were obtained 1-2 d after surgery, before and during inflation of the balloon in the ductus venosus. At each sample time, radioactive microspheres were injected to determine organ blood flow and the distribution of umbilical venous blood flow. During balloon inflation, the percentage of umbilical venous return passing through the ductus venosus was reduced from 38 +/- 15% to 1 +/- 0.5%. Umbilical-placental blood flow was unchanged from control values of 181 +/- 33 mL/min/kg. Total liver blood flow increased from 346 +/- 98 to 553 +/- 105 mL/min/100 g. Pressure in the inferior vena cava did not change, but umbilical venous pressure increased from 7.2 +/- 2.7 to 8.7 +/- 3.5 mm Hg. Total vascular resistance across the liver and ductus venosus increased from 0.013 +/- 0.006 to 0.020 +/- 0.011 during ductus venosus obstruction. Fetal heart rate, arterial blood pressure, and descending aortic pH and blood gases were unchanged, as was oxygen content in the descending aorta and carotid artery. Organ blood flows, combined ventricular output, and oxygen delivery were also unchanged. In five animals, these studies were repeated during maternal hypoxemia.(ABSTRACT TRUNCATED AT 250 WORDS)
静脉导管可使从脐 - 胎盘循环回流的高氧血绕过肝脏，据信这有助于将此血液优先分配至胎儿脑和心脏。为检验这一假说，我们构建了一个模型，可在长期插管的胎羊中急性阻塞静脉导管。在7只胎羊中，将一根 Swan - Ganz 导管插入下腔静脉，使球囊尖端推进至静脉导管内。术后1 - 2天，在静脉导管内球囊充气前和充气过程中进行对照测量。在每个采样时间，注射放射性微球以确定器官血流及脐静脉血流分布。在球囊充气过程中，经静脉导管的脐静脉回流百分比从38±15%降至1±0.5%。脐 - 胎盘血流与对照值181±33 mL/min/kg 相比无变化。肝脏总血流量从346±98增加至553±105 mL/min/100 g。下腔静脉压力未改变，但脐静脉压力从7.2±2.7升高至8.7±3.5 mmHg。在静脉导管阻塞期间，肝脏和静脉导管的总血管阻力从0.013±0.006增加至0.020±0.011。胎儿心率、动脉血压、降主动脉pH值和血气均未改变，降主动脉和颈动脉中的氧含量也未改变。器官血流、联合心室输出量和氧输送也未改变。在5只动物中，在母体低氧血症期间重复了这些研究。（摘要截短至250字）
