pathophysiological study of fetal distress using chronic preparation in sheep

我们对怀孕110至130天的怀孕绵羊进行了手术。在进行颈动脉血管插管、应用心脏电极并连接脐带封堵器后，将胎儿送回子宫以完成妊娠期。连续监测胎心率、胎儿动脉血压、脐动脉血流、宫内压、母体动脉血压。手术后第5天，当血气值和胎心率模式指示生理状态时，此时，我们进行了我们的实验。实验采用连续完全脐带阻断法，分析胎儿和母体血气，测定血浆去甲肾上腺素和肾上腺素。胎儿心率减速曲线下降段的斜率降低，并与胎儿动脉pH值、碳酸氢盐和血浆去甲肾上腺素和肾上腺素浓度的对数密切相关。反复脐带牵拉时，胎儿心率减速斜率可预测胎儿酸碱平衡及内分泌状态。当胎儿酸血症进展到动脉pH值约为7.15时，在释放脐带压迫后立即观察到特征性的过冲加速。当胎儿动脉pH值低至7.15时，脐带压迫引起的胎儿缺氧性酸血症未引起收缩期/舒张期血流速度比值的变化。

We operated on the pregnant sheep from 110 to 130 days of pregnancy. After performing cannulation of the carotic vessels, applying cardioelectrodes, and attaching an occluder of the umbilical cord, the fetuses were returned to the uterus to complete the gestational period. We monitored FHR pattern, fetal arterial blood pressure, umbilical arterial blood flow, intrauterine pressure, maternal arterial blood pressure continuously. After the fifth day of the operation, when blood gas value and FHR pattern pattern indicated the physiological state, at this point, we performed our experiments. The experiment was made of serial complete umbilical cord occlusion.We analyzed fetal and maternal blood gases, and measured plasma norepinephirine and epinephrine. The slope of the descending limb of the fetal heart rate deceleration curve decreased and correlated strongly with fetal arterial pH, bicarbonate, and logarithmic plasma norepinephrine and epinephrine concentration. During repeated umbilical cord compresion, the fetal acid-base and hormonal state was predicted by the fetal heart rate deceleration slope. When fetal acidemia progressed to an arterial pH of around 7.15, a characteristic overshoot acceleration was observed immediately after the release of cord compression. Fetal hypoxic acidemia induced by cord compression caused no change in the ratio of systolic/diastolic blood velocity when fetal arterial pH was as low as 7.15.