Baxi L V, Petrie R H, James L S
Am J Obstet Gynecol. 1979 Dec 15;135(8):1109-12. doi: 10.1016/0002-9378(79)90744-0.
To test the hypothesis that fetal heart rate (FHR) changes following paracervical block may be secondary to fetal hypoxia, human fetal oxygenation was measured continuously using a transcutaneous electrode. Following the block, each fetus demonstrated a decline in oxygen tension (tcPO2) at 5 minutes, which reached its lowest value at a mean of 11.5 minutes and remained at this level for an average of 3 minutes. Following the block, FHR variability increased at 5.2 minutes. reaching its maximal level by a mean of 7.5 minutes. By 11 minutes, a decrease in FHR variability was noted, which lasted for approximately 17 minutes. Decreased variability was not uniformly associated with low tcPO2. On some occasions, fetal tcPO2 declined even in the absence of increased uterine activity, which was noted at times following the block. The severity of the tcPO2 decline appears related to the analgesic effectiveness of the block.
为了验证宫颈旁阻滞术后胎儿心率（FHR）变化可能继发于胎儿缺氧这一假设，使用经皮电极连续测量了胎儿的氧合情况。阻滞术后，每个胎儿的氧分压（tcPO2）在5分钟时下降，平均在11.5分钟时降至最低值，并在此水平维持平均3分钟。阻滞术后，FHR变异性在5.2分钟时增加，平均在7.5分钟时达到最大值。到11分钟时，FHR变异性降低，持续约17分钟。变异性降低并非都与低tcPO2相关。在某些情况下，即使子宫活动未增加，胎儿tcPO2也会下降，这在阻滞术后有时会出现。tcPO2下降的严重程度似乎与阻滞的镇痛效果有关。
