Acute fetal hypoxic bradycardia: solving the chemoreception puzzle.
Acute fetal hypoxic bradycardia: solving the chemoreception puzzle.
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DOI：
10.1113/jp280529
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发表时间：
2020-10
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影响因子：
--
通讯作者：
Thornburg KL
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作者：
Thornburg KL
当胎儿生理学家看到胎儿心率急剧下降时，她或他可能会立即认为-胎儿低氧血症→胎儿高血压→压力反射性心动过缓;这个顺序在生理学知识中已经确立。但是，这一系列的事件是否可以解释胎儿对脐带完全闭塞的反应，就像人类分娩时可能发生的那样？Lear et al.的手稿。(Lear例如，2020）报道了在胎羊（妊娠约125天）中进行的实验，该实验旨在测试与子宫内脐带闭塞相关的压力感受器介导的心动过缓与化学感受介导的心动过缓的比较作用。这个问题具有相当大的意义，因为心率监测仍然是产房分娩管理的重要工具。此外，了解胎儿反射本身就很重要，作者研究了近足月胎羊在三种情况下的生理反应：1）短暂重复1分钟的脐带闭塞事件; 2）延长15分钟的完全闭塞事件和3）高血压反应的苯肾上腺素输注刺激压力感受器反射。在长时间的闭塞实验中，胎儿被用来测量近红外光谱变化作为脑氧合的指标。
When a fetal physiologist sees a rapid precipitous drop in fetal heart rate, she or he may immediately think—fetal hypoxemia→ fetal hypertension→ baroreflex bradycardia; this sequence is well established in physiological lore. But does this sequence of events explain the fetal response to complete cord occlusion as might occur in human labor? The manuscript by Lear et al.(Lear et al., 2020) reports on experiments in fetal sheep (~ 125 days gestation) designed to test the comparative roles of baroreceptor-mediated bradycardia associated with umbilical cord occlusion in utero vs. bradycardia mediated by chemoreception. The issue has considerable significance because heart rate monitoring remains an important tool for management of labor in the delivery room. Furthermore, understanding fetal reflexes is important in its own right.The authors investigated physiological responses in near-term fetal sheep under three conditions: 1) brief repeated 1 minute umbilical cord occlusion episodes; 2) prolonged 15 minute episodes of complete occlusion and 3) hypertensive responses to an infusion of phenylephrine to stimulate the baroreflex. In the prolonged occlusion experiments, fetuses were instrumented to measure near-infrared spectroscopic changes as indicators of cerebral oxygenation.