pathophysiological study of fetal distress using chronic preparation in sheep

我们对怀孕110至130天的绵羊进行了手术。在对颈动脉插管，应用心脏电极和连接脐带封堵器后，将胎儿送回子宫以完成妊娠期。连续监测FHR模式、胎儿动脉血压、脐动脉血流、宫内压、母体动脉血压。在手术第五天，当血气值和FHR模式显示生理状态时，我们进行实验。采用连续完全性脐带阻断实验。我们分析了胎儿和母亲的血气，并测量了血浆去甲肾上腺素和肾上腺素。胎儿心率降速曲线降肢斜率减小，且与胎儿动脉pH值、碳酸氢盐、血浆去甲肾上腺素和肾上腺素浓度的对数值密切相关。在重复脐带压缩过程中，胎儿的酸碱和激素状态可以通过胎儿心率减速斜率来预测。当胎儿酸血症进展到动脉pH约7.15时，释放脐带压迫后立即观察到特征性超调加速。当胎儿动脉pH低至7.15时，脐带压迫引起的胎儿缺氧酸血症对收缩/舒张血流速度比无影响。

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.