LINEAR AND NONLINEAR FETAL HEART RATE ANALYSIS OF NORMAL AND INTRAUTERINE GROWTH RESTRICTED FETUS AFTER VIBROACOUSTIC STIMULATION

초록

Objective : The objectives of this study is to investigate characteristics of Intrauterine growth restriction(IUGR) using chaos and canonical correlation analysis(CCA). Method : We made use of nonstress test(NST) checking for pregnancy with non-linearity and compared normal with IUGR using approximate entropy(ApEn), correlation dimension(CD), Canonical Correlation Analysis(CCA) on the basis of linearity and statistical analysis. Result : The variables of fetal heart rate(FHR) between these two groups had no significant difference. But IUGR was less chaotic than that of normal fetuses (ApEn: 0.88±0.01 vs. 0.65±0.01, CD: 3.88±0.02 vs. 3.51±0.02) (p < 0.01) except canonical correlation analysis(CCA: 0.638±0.10 vs. 0.527±0.10) (p < 0.1). Conclusion : The present study succeeded in showing that heart rate patterns of the IUGR fetus, with nonlinearity and linearity, are significantly different from that of normal fetuses simultaneously. This result means that the canonical ensemble and chaotic indexes appear to be sensitive statistic in detecting subtle and possibly important changes in FHR signal from IUGR. As this FHR data is non-linear, we should be applied machine learning methods compared to common statistical methods(logistic regression, chi-square test etc.).