Wärmeflußmessungen vom fetalen Skalp und Kardiotokographie zur Vorhersage von Azidosezuständen sub partu - ein Vergleich zweier Methoden

Abstract

Although the efficacy of electronic foetal heart rate (FHR) monitoring and intermittent scalp blood sampling is well established, these methods still result in a considerable number of false positive and negative predictions. Consequently, methods, which improve the accuracy of prediction, are still under study. Heat flux measurements from the foetal scalp have been shown to relate to the metabolic condition of the foetus during delivery. In this study, we investigated the predictive power of measuring scalp heat flux and monitoring the FHR electronically, and the combination of both. In 136 foetuses the scalp heat flux was measured by means of a heat flux transducer, 2.5 cm in diameter, attached to the foetal scalp after the cervix had dilated to greater than 2.5 cm. Heat flux was regarded as abnormal, if the heat flux was less than 10 w/m2 or greater than 21 w/m2, or fell by more than 20% of its initial value during the last 30 min before delivery. FHR tracings were considered abnormal, if they resulted in therapeutic consequences like oxygen mask for the mother, scalp blood sampling or immediate operative delivery. Foetuses were considered acidotic, if their pH in the arterial cord blood was less than 7.20. Accuracy of prediction was described by appropriate parameters. The scalp heat flux method resulted in a higher specificity (80.4% vs. 72.5%), positive predictive value (59.2% vs. 51.7%), and overall accuracy (82% vs. 77%) than FHR monitoring. Sensitivity of FHR monitoring was slightly higher than the one of heat flux method (88.2% vs 85.3%). Combining both methods resulted in a sensitivity of 100% thus detecting all acidotic foetuses, but specificity fell to 62%.(ABSTRACT TRUNCATED AT 250 WORDS)