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Entropy 2017, 19(5), 225;

Entropy Information of Cardiorespiratory Dynamics in Neonates during Sleep

Department of Psychiatry, Columbia University College of Physicians & Surgeons, New York, NY 10032, USA
Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
Department of Psychosomatic Medicine and Psychotherapy, University of Freiburg, 79106 Freiburg, Germany
Author to whom correspondence should be addressed.
Academic Editor: Roberto Hornero
Received: 30 March 2017 / Revised: 11 May 2017 / Accepted: 12 May 2017 / Published: 15 May 2017
(This article belongs to the Special Issue Entropy and Sleep Disorders)
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Sleep is a central activity in human adults and characterizes most of the newborn infant life. During sleep, autonomic control acts to modulate heart rate variability (HRV) and respiration. Mechanisms underlying cardiorespiratory interactions in different sleep states have been studied but are not yet fully understood. Signal processing approaches have focused on cardiorespiratory analysis to elucidate this co-regulation. This manuscript proposes to analyze heart rate (HR), respiratory variability and their interrelationship in newborn infants to characterize cardiorespiratory interactions in different sleep states (active vs. quiet). We are searching for indices that could detect regulation alteration or malfunction, potentially leading to infant distress. We have analyzed inter-beat (RR) interval series and respiration in a population of 151 newborns, and followed up with 33 at 1 month of age. RR interval series were obtained by recognizing peaks of the QRS complex in the electrocardiogram (ECG), corresponding to the ventricles depolarization. Univariate time domain, frequency domain and entropy measures were applied. In addition, Transfer Entropy was considered as a bivariate approach able to quantify the bidirectional information flow from one signal (respiration) to another (RR series). Results confirm the validity of the proposed approach. Overall, HRV is higher in active sleep, while high frequency (HF) power characterizes more quiet sleep. Entropy analysis provides higher indices for SampEn and Quadratic Sample entropy (QSE) in quiet sleep. Transfer Entropy values were higher in quiet sleep and point to a major influence of respiration on the RR series. At 1 month of age, time domain parameters show an increase in HR and a decrease in variability. No entropy differences were found across ages. The parameters employed in this study help to quantify the potential for infants to adapt their cardiorespiratory responses as they mature. Thus, they could be useful as early markers of risk for infant cardiorespiratory vulnerabilities. View Full-Text
Keywords: newborn; sleep state; autonomic nervous system; heart rate variability; transfer entropy newborn; sleep state; autonomic nervous system; heart rate variability; transfer entropy

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Lucchini, M.; Pini, N.; Fifer, W.P.; Burtchen, N.; Signorini, M.G. Entropy Information of Cardiorespiratory Dynamics in Neonates during Sleep. Entropy 2017, 19, 225.

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