慢性ストレス下における胎児well-being評価に関する総合的研究(2 胎児wellbeingの臨床的評価法 : その精度と限界)

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For the clinical assessment of fetal well being in chronic stressed environments, we must understand fetal physiological response against altered intrauterine condition. Mild and long term stressed fetal model by increasing myometrial contracture by oxytocin pulses to the ewes showed 1) altered fetal oxygenation of lower pO_2 but higher O_2 content, left-shifted O_2 dissociation curve to resist acute short epoch of insults, 2) matured cardiovascular control of baro-reflex response, 3) accelerated maturation of the high voltage-low voltage electrocorticogram and the state establishment. Ontogenic changes in baro-reflex study showed that the vagal reflex of bradycardia induced by reduced venous return was not obvious at 110 dGA. This reflex was gradually ominous as gestational age progressed and severest at 135 dGA. The baro-reflex slope is sharp at 135 dGA. This result indicates that there is a critical period of sympathetic and parasympathetic balance in control of baro-reflex when the fetal circulation is easily breaks down. Steroid administration to the fetus showed changes in blood pressure and heart rate as well as resetting of baro-reflex response. These results indicate that fetuses in chronic stress adapt to the altered environment by accelerating their functional courses of maturation. By maturation, fetal cardiovascular and neurological function is changed and fetal response to additional stresses is modified. These results are translated to the clinical findings that there must be a well-looking period in spite of the fetuses are in chronic stress and that the reaction to additional acute stress to the fetuses must be masked by their matured functions. These physiological modification of the fetus considered to be the reason of the difficulty in diagnosing fetal well-being in chronic stress. To evaluate human fetal condition in detail, accurate measurements of fetal heart rate at beat to beat, obtainment of fetal blood pressure information, quantitative assessment of fetal behavior must be promising methods. We proposed a new method using multi-channel pulsed Doppler. Application of two dimensional auto correlation to Doppler signals confirmed to achieve less than 1 bpm accuracy in FHR measurements. With minute displacement measurement technique, the pulse wave of aortic wall movements were measured at the order of micrometers. Fetal breathing movements were real-timely measured and auto-recognized at around 60% of conventional counting method. These non-invasive fetal monitoring techniques should be next generation fetal monitoring devices.
社団法人日本産科婦人科学会の論文
2002-08-01

慢性ストレス下における胎児well-being評価に関する総合的研究(2 胎児wellbeingの臨床的評価法 : その精度と限界)

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