Neuroscience Letters 437 (2008) 103–106 Contents lists available at ScienceDirect Neuroscience Letters journal homepage: www.elsevier.com/locate/neulet Correlation between EEG burst-to-burst intervals and HR acceleration in preterm infants Klaus Pfurtscheller a,∗ ,G¨ unther Bauernfeind b , Gernot R. M ¨ uller-Putz b , Berndt Urlesberger a , Wilhelm M ¨ uller a , Gert Pfurtscheller b a Division of Neonatology, Department of Pediatrics, University Hospital of Graz, Auenbruggerplatz 30, 8036 Graz, Austria b Institute for Knowledge Discovery, BCI-Lab, Graz University of Technology, Austria article info Article history: Received 7 January 2008 Received in revised form 19 February 2008 Accepted 27 March 2008 Keywords: Heart rate variability (HRV) Heart rate response Autonomic nervous system Amplitude-integrated EEG Preterm infants EEG bursts Maturation abstract One objective of this paper is to confirm the coupling between heart rate (HR) changes and electroen- cephalographic (EEG) bursts (as reported for the first time in Pfurtscheller et al. [K. Pfurtscheller, G.R. M¨ uller-Putz, B. Urlesberger, W. M¨ uller, G. Pfurtscheller, Relationship between slow-wave EEG bursts and heart rate changes in preterm infants, Neurosci. Lett. 385 (2) (2005) 126–130]) in a larger group of preterm infants. Other objectives are to report on semi-automatic detection of burst-to-burst intervals (BBI, time period between the onsets of 2 consecutive EEG bursts) and on correlations between BBI and HR changes. A group of 34 preterm infants with a conceptional age (CA) of 35.9 ± 0.6 weeks (mean ± S.D.) was stud- ied. Periods with a length of about 10min with low HR variability and discontinuous EEG were selected from long-term EEG and ECG registrations and analyzed. From the automated detection of EEG bursts, an estimate for the mean burst-to-burst interval was obtained. EEG trials with a duration of 16 s and a single EEG burst in the middle, were selected and averaged together with the corresponding instantaneous HR trials. It was found that preterm infants without evidence of neurological deficit and with normal devel- opment revealed a mean BBI of 13.4 ± 2.6 s (mean ± S.D.) and a HR increase of 1.7 ± 0.9 bpm (mean ± S.D.) during the occurrence of EEG bursts. This HR increase is comparable with the earlier reported increase of 1.9 ± 0.8 bpm. A significant negative correlation of r = 0.453 (p < 0.01) was found between BBI and HR increase and a positive correlation between CA and HRV (r = 0.438, p < 0.01) and between CA and HRI (r = 0.452, p < 0.01). © 2008 Elsevier Ireland Ltd. All rights reserved. Both the heart rate (HR) and the electroencephalographic (EEG) temporal patterns are highly variable during maturation. Therefore the common analysis of EEG and heart rate can help to monitor cere- bral and autonomic functioning during the maturational processes after preterm birth. During quiet sleep and a conceptional age (CA) of approximately 36 weeks, the EEG shows a semi-discontinuous EEG pattern [1,8] and a low variability of the heart rate (HRV) [15]. It has been shown recently for the first time that a coupling exists in quiet sleep between EEG bursts and heart rate changes in preterm infants [11]. The onset of EEG bursts in semi-discontinuous EEG during quiet sleep was accompanied by an HR acceleration of 1.9 ± 0.8 bpm (mean ± S.D.) lasting 5.0 ± 1.0 s (mean ± S.D.) [12]. At this time the exact mechanism responsible for the common behav- ior of cortical and brain stem activation is unknown and needs further discussion. ∗ Corresponding author. Tel.: +43 650 461 4363; fax: +43 316 385 2678. E-mail address: k.pfurtscheller@tugraz.at (K. Pfurtscheller). The goals of this paper are: (i) to confirm the coupling between EEG and HR, as published already [12], in a larger group of preterm infants; (ii) to report on semi-automatic detection of EEG burst-to-burst intervals (BBI) (time period between the onsets of 2 consecu- tive bursts); and (iii) to report on correlations between BBI and HR changes. The measurements were carried out in a group consisting of 34 neurologically healthy premature infants with a gestational age (GA) of 32.4 ± 2.2 weeks (mean ± S.D.) (range: 29.0–35.5 weeks) and a CA of 35.9 ± 0.6 weeks (range: 34.2–36.7 weeks) at the time of data acquisition. Selection criteria for participation were premature birth with an uncomplicated course during the stay at the neonatal intensive care unit without any neurological impairment or con- genital malformations. All infants had a short period of ventilatory support during their first week of life because of infant respiratory distress syndrome (IRDS) and a minority received an oral medica- tion with caffeine because of periodic breathing or apnea. During 0304-3940/$ – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2008.03.079