Aarnoudse J G, Oeseburg B, Kwant G, Zwart A, Zijlstra W G, Huisjes H J
Biol Neonate. 1981;40(5-6):252-63. doi: 10.1159/000241501.
A description is given of the effect of hypercapnic acidaemia and hypocapnic alkalaemia on scalp tissue PO2 as measured with a subcutaneous needle-electrode and a transcutaneous electrode in 6 fetal lambs. The experiments were carried out under general anaesthesia with the fetus kept in utero. Hypocapnia was induced by hyperventilating the ewe and hypercapnia was achieved by administering extra CO2 to the ewe. Fetal carotid arterial, subcutaneous and transcutaneous PO2 were continuously recorded, and fetal and maternal arterial pH and arterial PCO2 were determined from blood samples taken at short intervals. In each experiment the H+ Bohr factor of fetal and maternal blood was measured. During hypocapnic alkalaemia, there was a fall in all fetal PO2 levels, whereas a marked rise was observed during hypercapnic acidaemia. The variations in fetal PO2 observed in vivo even exceeded the variations due to the H+ Bohr effect (measured in vitro). This was due to small variations in fetal carotid arterial oxygen saturation, which tended to fall during hypocapnic alkalaemia and to rise during hypercapnic acidaemia. The results of these findings strongly suggest that tissue PO2, as measured with the subcutaneous and transcutaneous electrodes, is dependent on the H+ Bohr effect. This adds to the uncertainty as to the value of subcutaneous and transcutaneous PO2 monitoring during labour as an early warning system for impending fetal asphyxia.
本文描述了在6只胎羊中，用皮下针电极和经皮电极测量高碳酸血症性酸血症和低碳酸血症性碱血症对头皮组织氧分压（PO2）的影响。实验在全身麻醉下进行，胎儿留在子宫内。通过给母羊过度通气诱导低碳酸血症，通过向母羊额外注入二氧化碳实现高碳酸血症。连续记录胎儿颈动脉、皮下和经皮的PO2，并每隔短时间采集血样测定胎儿和母体的动脉pH值及动脉二氧化碳分压（PCO2）。在每个实验中，测量胎儿和母体血液的H+玻尔因子。在低碳酸血症性碱血症期间，所有胎儿PO2水平均下降，而在高碳酸血症性酸血症期间观察到显著升高。在体内观察到的胎儿PO2变化甚至超过了因H+玻尔效应（体外测量）引起的变化。这是由于胎儿颈动脉血氧饱和度的微小变化，在低碳酸血症性碱血症期间趋于下降，在高碳酸血症性酸血症期间趋于上升。这些研究结果强烈表明，用皮下和经皮电极测量的组织PO2依赖于H+玻尔效应。这增加了分娩期间将皮下和经皮PO２监测作为胎儿窘迫早期预警系统的价值的不确定性。
