The effect of hypoxia on fetal Cardiovascular System

1)动物实验采用绵羊慢性准备模型，连续记录胎心率(FHR)、脑电、心电、气管压和胎儿血压(FBP)，发现FBP、FHR和胎儿呼吸运动(FBM)在睡眠周期的各个时期都有明显的变化及其量质的差异。与胎动一致的加速(ACC)(幅度>40次/分，持续时间>40s)、胎动爆发(FBM)和FBP升高是低电压高频(LVHF)睡眠时的特征，而DCC(DCC)和胎动(FM)在高压低频(HVLF)睡眠时明显增加，这一趋势在较年轻的胎儿中更为明显。用去甲肾上腺素(NE)和精氨酸加压素(AVP)对胎羊和成年家兔连续灌流，观察这些激素对胎儿心血管系统的影响。而NE则导致…升高FBP升高，FHR、AVP降低，FBP持续升高，FHR及其变异性降低，FBM明显抑制。采用B超和MT320型胎动记录仪观察28~40周胎儿的胎心、胎动情况。与滚动运动相一致的ACC波幅和持续时间随孕周进展而增加，其类型以活跃睡眠为特征。胎心率监测采用75 Hz、74db振动声刺激(Vava)，以引起应激状态。大多数胎儿在心率上对ACC有反应，反应程度随妊娠提前几周而不同。我们的反应分为4组，由5种类型组成。1型(ACC型)和2型(心动过速型)预后良好。3型(三相型)为脊髓受累者(第2组)。4型(DCC型)和5型(无反应型)预后较差(第3、4组)。较少

1) Animal Experiment Fetal heart rate (FHR), EEG, ECG, Tracheal pressure and fetal blood pressure (FBP) recorded continiously by using sheep chronic prepartion model revealed the obvious changes of FBP, FHR, fetal breathing movement (FBM) as well as its quantitative and qualitative differences in each period of sleeping cycles. While the Accerelation (ACC) (amplitude more than 40bpm, duration more than 40sec) coincident with fetal movement, burst of fetal breathing movement (FBM) and increase of FBP were characteristic during low voltage high frequency (LVHF) sleep, the deccerelation (DCC) with fetal movement (FM) were characteristicaly increased in high voltage low frequency (HVLF) sleep and this tendency was more prominent in younger fetuses. Nor epinephrine (NE) and arginine vasopressin (AVP) increased during hypoxia were infused continuously to fetal lamb and abult domestic rabbits t clalify the effects of these hormones on fetal cardiovasuclar system. While Ne resulted in increase … More of FBP and decrease in FHR, AVP resulted in persistent increase in FBP and decrease in FHR and in its variability as well as marked inhibition of FBM.2) Human fetus FM. FBM and FHR were observed by using ultrasound and MT 320 fetal movement recorder during 28-40 gestational weeks. The amplitude and duration of ACC coincident with rolling movent were increased according to progress of gestaional weeks and that type of ACC was characteristic in active sleep. In order to cause a stress situation, 75Hz, 74db vibro-acoustic stimultion (VAST) was performed during the fetal heart rate monitoring. The majority of the fetuses reacted with an ACC in heart rate and the degree of reactivity varied with the weeks of advancement of pregnancy. Our responses were classified into 4 groups, consisting of 5 types. Type-1(ACC type) and type-2(tachycardia type) were in good prognosis. Type-3(triphasic type) was those with cord involvement (group2). Type-4 (DCC type) and type-5 (non-response type) had poor prognosis (group3,4). Less