Linear and nonlinear parameters for the analysis of fetal heart rate signal from cardiotocographic recordings

Abstract

Antepartum fetal monitoring based on the classical cardiotocography (CTG) is a noninvasive and simple tool for checking fetal status. Its introduction in the clinical routine limited the occurrence of fetal problems leading to a reduction of the precocious child mortality. Nevertheless, very poor indications on fetal pathologies can be inferred from the even automatic CTG analysis methods, which are actually employed. The feeling is that fetal heart rate (FHR) signals and uterine contractions carry much more information on fetal state than is usually extracted by classical analysis methods. In particular, FHR signal contains indications about the neural development of the fetus. However, the methods actually adopted for judging a CTG trace as "abnormal" give weak predictive indications about fetal dangers. We propose a new methodological approach for the CTG monitoring, based on a multiparametric FHR analysis, which includes spectral parameters from autoregressive models and nonlinear algorithms (approximate entropy). This preliminary study considers 14 normal fetuses, eight cases of gestational (maternal) diabetes, and 13 intrauterine growth retarded fetuses. A comparison with the traditional time domain analysis is also included. This paper shows that the proposed new parameters are able to separate normal from pathological fetuses. Results constitute the first step for realizing a new clinical classification system for the early diagnosis of most common fetal pathologies.

The Obestatin/Ghrelin System as a Novel Regulatory Mechanism of Iris Muscle Contraction

“…Some of those indices, previously used by some of us in FHR analysis (Vieira et al 2004, Felgueiras et al 1998, may be useful, as the scaling behaviour of HR seems to be selectively related to the alpha-adrenergic activity whereas entropy appears to be related to cholinergic activity (Beckers et al 2006b). Those indices were outside the scope of this study, which was designed, like our last series of studies on FHR (Gonçalves et al 2006a(Gonçalves et al , 2006b(Gonçalves et al , 2007, to be more comparable with other FHR studies published in the literature (Magenes et al 2000, Signorini et al 2003. On the other hand, in this study an evaluation of entropy was performed in more depth than in other studies.…”

Estimating Fetal Gestational Age Using Cardiac Valve Intervals

“…More details can be found in [17]. -Combined model: Combined valve timing and FHRrelated parameters.…”

Computerised analysis of antepartum foetal heart parameters: New reference ranges

“…ApEn has been introduced in based on the theory that human well-being is associated to an high level of irregularity of biomedical time series (e.g. heart rate, respiratory acidosis, and dynamics of hormone release) (Signorini et al 2003;Xiaotian et al 2005;Ferrario et al 2006). We found that the mean value of ApEn showed a slight negative correlation with gestational age.…”

“…The middle frequency (MF 0.15-0.5 Hz) depends on foetal movements and maternal breathing activity and it is typical of FHR spectrum. LF/ (HF þ MF) ratio quantifies the autonomic balance between neural control mechanisms from different origin (Signorini et al 2003).…”

“…Computerised cardiotocography (cCTG) improves foetal monitoring reliability as it standardises CTG evaluation with automatic estimation of foetal heart rate (FHR) parameters (Signorini et al 2003). In fact, cCTG is characterised by objectivity and consistency (Dawes et al 1996) as it performs an automatic trace analysis, implementing diagnostic criteria accepted in clinical obstetric practise (Gagnon et al 1993;Pardey et al 2002).…”