Richardson B S, Bocking A D
Department of OB/GYN, University of Western Ontario, London, Canada.
Comp Biochem Physiol A Mol Integr Physiol. 1998 Mar;119(3):717-23. doi: 10.1016/s1095-6433(98)01010-1.
When oxygenation is compromised the fetus is capable of a number of adaptive responses, both protective and potentially pathologic, which can be categorized as those affecting fetal metabolism and those affecting fetal oxygen transport. However, both the extent and the duration of the impairment in oxygenation will bear on these adaptive responses. While fetal O2 extraction is increased when oxygenation is acutely compromised thus maintaining O2 consumption, with chronic hypoxemia there is a decrease in O2 consumption paralleling that in O2 delivery and contributed to by the resultant fall-off in growth and alterations in behavioural activity. While a redistribution of blood flow to vital organs continues to be evident, this will be less pronounced than that seen with acute hypoxemia reflecting diminished hormonal changes, underlying metabolic alterations, and the extent to which fetal blood gases are normalized. Much of this information is based on experimental data using unanesthetized fetal sheep with chronic catheterization; however, clinical outcome data and the use of investigative techniques including ultrasound scanning and cordocentesis have supported the relevance of this experimental data to the human situation.
当氧合作用受到损害时，胎儿能够做出多种适应性反应，既有保护性的，也可能是病理性的，这些反应可分为影响胎儿代谢的反应和影响胎儿氧运输的反应。然而，氧合作用受损的程度和持续时间都会影响这些适应性反应。当氧合作用急性受损时，胎儿的氧摄取会增加，从而维持氧消耗；而在慢性低氧血症时，氧消耗会减少，与氧输送的减少平行，这是由于生长下降和行为活动改变所致。虽然血液向重要器官的重新分布仍然很明显，但这将不如急性低氧血症时那么显著，这反映了激素变化减少、潜在的代谢改变以及胎儿血气正常化的程度。这些信息大多基于对未麻醉的慢性插管胎羊的实验数据；然而，临床结果数据以及包括超声扫描和脐血穿刺在内的研究技术的应用，支持了这些实验数据与人类情况的相关性。
