Continuous, transcutaneous oxygen tension measurements in experiments with rhesus monkeys and pregnant ewes.

After the first report by HUCH, HUCH, MEINZER and LÜBBERS on transcutaneous measurements of oxygen tension several papers describing this or similar electrodes based on the CLARK principle have been published [l, 3, 4, 12, 15, 18]. The technique has mainly been tested in perinatal medicine, but also in adults [7,8,13]. A publication on intrapartum registrations of human fetuses in considerable numbers came in 1977 [6], but other mainly preliminary reports have appeared during the last years [5,12,16]. From studies of newborn infants and adults it is knows that the correlation between intraarterial (Pa02) and transcutaneous oxygen tension (tcPO2) is high provided the peripheral circulation is adequate. Several investigors have found that at Pa02 levels of 50 mm Hg (6.5 kPa) and higher the transcutaneous measuring System works well and gives correct information about PaO2 changes, moreover predicts the Pa02 level with good reliability. Coefficients of correlation of 0.9 or higjier have been reported [2, 9, 10, 11, 13, 14, 17]. Although the CLARK electrode is linear from zero to more than 1000mm Hg (135 kPa) it is not known if the correlation between Pa02 and tcP02 is equally high at fetal levels when the pressure gradient for oxygen from the arterialized capillary blood to the tcP02 electrode is sinall. We have therefore studied the reliability of the electrode system in vivo at fetal Pa02 levels. Moreover, äs only one study [18] Curriculum vitae