Pulgar Victor M, Zhang Jie, Massmann G Angela, Figueroa Jorge P
Perinatal Research Laboratory, Department of Obstetrics and Gynecology, Center for Research in Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
J Soc Gynecol Investig. 2006 Sep;13(6):404-11. doi: 10.1016/j.jsgi.2006.05.007. Epub 2006 Jul 31.
To assess the effects of prolonged mild hypoxemia on fetal brain electrocorticogram (ECoG) in late gestation.
Fetal and maternal catheters were placed under general anesthesia and animals allocated at random to receive intratracheal maternal administration of either nitrogen (n = 8) or compressed air (n = 8). Five days after surgery (125 days' gestational age), nitrogen infusion was adjusted to reduce fetal brachial artery PO2 by 25%. The targeted decrease in fetal oxygenation was maintained for 5 days while fetal ECoG activity and fetal and maternal cardiovascular variables were continuously recorded. Data are presented as mean +/- SEM and were analyzed by two-way analysis of variance (ANOVA) or two-sample t test.
Nitrogen infusion decreased fetal Po2 by 26% (20.5 +/- 1.7 versus 14.3 +/- 0.8) without changing fetal PCO2 or pH. Mild fetal hypoxemia was associated with fetal tachycardia and increased fetal blood pressure (P < .05). Fetal ECoG in hypoxic fetuses showed a significant decrease in the time spent in high voltage (HV) (P < .05) and an increase in the time spent in low voltage (LV) and in the number of low voltage events (P < .05). Also, a significant decrease in the proportion of 1-4 Hz and an increase in the proportion of 13-20 Hz frequencies was observed in LV events without a significant change in the frequency profile of HV events (P < .05).
Prolonged mild hypoxemia significantly altered fetal homeostasis as reflected by the sustained tachycardia and increased blood pressure. Fetal ECoG activity was affected significantly in a qualitatively and quantitative manner by mild prolonged hypoxemia.
评估妊娠晚期长期轻度低氧血症对胎儿脑皮质电图（ECoG）的影响。
在全身麻醉下放置胎儿和母体导管，将动物随机分配接受经气管向母体注入氮气（n = 8）或压缩空气（n = 8）。手术5天后（妊娠125天），调整氮气注入量以使胎儿肱动脉PO2降低25%。在持续记录胎儿ECoG活动以及胎儿和母体心血管变量的同时，将胎儿氧合的目标降低水平维持5天。数据以平均值±标准误表示，并通过双向方差分析（ANOVA）或两样本t检验进行分析。
注入氮气使胎儿Po2降低26%（20.5±1.7对14.3±0.8），而胎儿PCO2或pH未发生变化。轻度胎儿低氧血症与胎儿心动过速和胎儿血压升高相关（P < 0.05）。缺氧胎儿的ECoG显示，高电压（HV）持续时间显著减少（P < 0.05），低电压（LV）持续时间和低电压事件数量增加（P < 0.05）。此外，在LV事件中观察到1 - 4 Hz频率比例显著降低，13 - 20 Hz频率比例增加，而HV事件的频率分布无显著变化（P < 0.05）。
长期轻度低氧血症显著改变了胎儿内环境稳态，表现为持续性心动过速和血压升高。长期轻度低氧血症在质量和数量上均对胎儿ECoG活动产生了显著影响。
