The continuous measurement of transcutaneous carbon dioxide tension (TcPCO2), an atraumatic tool to verify fetal acidosis?
TcPCO2 monitoring of the fetus during labour was evaluated as an atraumatic tool to identify or exclude fetal acidosis in 224 high-risk deliveries. A heated electrochemical sensor with a measuring temperature of 39 degrees C (n = 105) or 44 degrees C (n = 119) was applied to the fetal scalp. There was a statistically significant correlation between the TcPCO2 and the fetal blood pH at both temperatures. The sensitivity of the method was 0.90 and 0.61 at the two measuring temperatures of 44 degrees or 39 degrees respectively and the specificity was 0.93 and 0.79 respectively. The negative predictive value was high (0.99 and 0.95 respectively), but the respective positive predictive values were only 0.53 and 0.24. We conclude that the continuous measurement of the TcPCO2 is a valid additional tool to exclude fetal acidosis in most cases where fetal distress is indicated by the heart rate pattern but a TcPCO2 value above the cut-off point should be verified by an additional method to avoid unnecessary operative deliveries.
Institute for Perinatal Medicine, Free University of Berlin, FRG.
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SC
Schmidt
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EZ
Saling
D000142:Acidosis, Respiratory / Q000097:blood / Q000175:diagnosis*; D001785:Blood Gas Monitoring, Transcutaneous; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis*; D005323:Fetal Monitoring / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011247:Pregnancy