Characterisation of neonatal cardiac dynamics using ordinal partition network

TL;DR

This study introduces a nonlinear network-based approach to analyze neonatal heart rate variability, revealing subtle differences in autonomic nervous system maturity between premature and full-term newborns.

Contribution

It presents a novel methodology using ordinal partition networks and complexity quantifiers to classify ANS conditions in newborns from RR interval data.

Findings

Time asymmetry is present in neonatal RR interval data.

Complexity quantifiers can differentiate premature and full-term newborns.

Conditional and global node entropies are effective for small embedding dimensions.

Abstract

The maturation of the autonomic nervous system (ANS) starts in the gestation period and it is completed after birth in a variable time, reaching its peak in adulthood. However, the development of ANS maturation is not entirely understood in newborns. Clinically, the ANS condition is evaluated with monitoring of gestational age, Apgar score, heart rate, and by quantification of heart rate variability using linear methods. Few researchers have addressed this problem from the perspective nonlinear data analysis. This paper proposes a new data-driven methodology using nonlinear time series analysis, based on complex networks, to classify ANS conditions in newborns. We map $74$ time series given by RR intervals from premature and full-term newborns to ordinal partition networks and use complexity quantifiers to discriminate the dynamical process present in both conditions. We obtain three complexity quantifiers (permutation, conditional and global node entropies) using network mappings from forward and reverse directions, and considering different time lags and embedding dimensions. The results indicate that time asymmetry is present in the data of both groups and the complexity quantifiers can differentiate the groups analysed. We show that the conditional and global node entropies are sensitive for detecting subtle differences between the neonates, particularly for small embedding dimensions ($m < 7$). This study reinforces the assessment of nonlinear techniques for RR intervals time series analysis.