The influence of signal representation on fetal heart rate variability analysis

Abstract

Analysis of variability of fetal heart rate (FHR) is very important in prediction of the fetal wellbeing. The beatto- beat variability is described quantitatively by the indices originated from invasive fetal electrocardiography which provides the FHR signal in a form of time event series. Nowadays, monitoring instrumentation is based on Doppler ultrasound technology. We used two bedside fetal monitors with different processing methods for heart beats detection and FHR signal determination: the autocorrelation and crosscorrelation techniques. Both monitors provide the output signal in a form of evenly spaced samples. The goal of this work was to evaluate the influence of signal representation on the indices describing FHR variability. For both monitors the indices calculated for the sampled signal decreased in relation to the indices determined from event series. © Springer-Verlag Berlin Heidelberg 2007.