Wallenburg H C, Verhoeff A, Jansen T C, Van der Wiel A R
Obstet Gynecol. 1984 Aug;64(2):239-43.
Equatorial compression of the fetal head is known to occur during labor; its effect on trancutaneous scalp PO2 (PtCO2) was investigated in acute experiments in four fetal lambs. Fetal PtCO2, and oxygen tension (PaO2) and flow in a carotid artery were continuously measured. Equatorial head compression was obtained by inflating a cuff around the fetal head. A strong relationship was shown to exist between PtCO2 and PaO2 values in the normoxemic and hypoxemic fetus. Stepwise compression of the fetal head resulted in a PtCO2 of zero at cuff pressures of 40 to 50 mmHg. Laborlike fetal head compression with an intensity of 50 to 70 mmHg and a duration of one minute resulted in a 30 to 60% fall in PtCO2. Fetal PaO2 remained stable in all experiments. The present findings indicate that values of PtCO2 during fetal head compression do not reflect fetal arterial oxygen tension. This questions the reliability of transcutaneous PO2 monitoring as a method of intrapartum surveillance.
已知胎儿头部在分娩过程中会发生赤道部受压；在对四只胎羊进行的急性实验中，研究了其对经皮头皮氧分压（PtCO2）的影响。连续测量胎儿的PtCO2、氧分压（PaO2）以及颈动脉血流。通过在胎儿头部周围充气袖带实现赤道部头部受压。结果显示，在正常血氧和低氧血症胎儿中，PtCO2与PaO2值之间存在密切关系。逐步压迫胎儿头部会导致袖带压力在40至50 mmHg时PtCO2为零。强度为50至70 mmHg、持续一分钟的类似分娩时的胎儿头部压迫会导致PtCO2下降30%至60%。在所有实验中，胎儿的PaO2保持稳定。目前的研究结果表明，胎儿头部受压期间的PtCO2值不能反映胎儿动脉氧分压。这对经皮氧分压监测作为产时监测方法的可靠性提出了质疑。
