Clinical experience on tcPco2 during labor

tcPco2 measurements in the fetus during labor were evaluated by analysing the clinical experience in 224 cases. This additional mode of supervision was performed in combination with continuous cardiotocography (CTG) and intermittent fetal blood sampling (FBA) in cases with suspect, prepathologic or pathologic heart rate patterns. The prechosen measuring temperature was 39 degrees C in 105 and 44 degrees C in 119 cases. The normal range of the tcPco2 was defined by calculating the mean value and two standard deviations in cases without hypoxic complications. The absolute values of the normal range were different according to the measuring temperature, when no correction factor was used. After adjusting the transcutaneous values to the blood gas level by means of the Severinghaus formular no significant differences in the tcPco2 values were notified for the two applied temperatures (39 degrees C and 44 degrees C). There is an obvious rise of tcPco2 with the progress of labor. Comparing the tcPco2 values with the pH values in the fetal blood we found a statistically significant correlation at either temperatures (p less than 0.001). Aiming at an early detection of raising acidity in the fetal blood, an action line of 55 mmHg after correction (80 mmHg at 44 degrees C, 63 mmHg at 39 degrees C) is an adequate basis for clinical intervention as all acidotic (pH less than 7.20) and the majority of preacidotic value (pH 7.20-7.24) can be excluded. One clinical benefit that can be expected by the additional use of tcPco2 is the reduction in the necessity of fetal blood sampling in a number of cases with abnormal heart rate patterns.(ABSTRACT TRUNCATED AT 250 WORDS)