Respiratory sinus arrhythmia during sleep in children with upper airway obstruction

Authors

  • Muammar M. Kabir,

    Corresponding author
    • Centre for Biomedical Engineering and School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
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  • Mark Kohler,

    1. School of Psychology, Social Work and Social Policy, University of South Australia, Adelaide, SA, Australia
    2. School of Paediatrics and Reproductive Health, Childrens Research Centre, The University of Adelaide, Adelaide, SA, Australia
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  • Yvonne Pamula,

    1. Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, SA, Australia
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  • James Martin,

    1. Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, SA, Australia
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  • Declan Kennedy,

    1. School of Paediatrics and Reproductive Health, Childrens Research Centre, The University of Adelaide, Adelaide, SA, Australia
    2. Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, SA, Australia
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  • Derek Abbott,

    1. Centre for Biomedical Engineering and School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
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  • Mathias Baumert

    1. Centre for Biomedical Engineering and School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
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Correspondence Muammar M. Kabir, School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005, Australia. Tel.: +61 8 8313-4115; fax: +61 8 8313-4360; e-mail: muammar.kabir@adelaide.edu.au

Summary

Upper airway obstruction during adulthood is associated with cardiovascular morbidity; cardiovascular consequences of childhood upper airway obstruction are less well established. This study aimed at investigating the effect of childhood upper airway obstruction on respiratory sinus arrhythmia as a measure of cardiac vagal modulation during night-time sleep. Overnight polysomnography was conducted in 40 healthy children (20 M; age: 7.5 ± 2.6 years; body mass index percentile: 60.7 ± 26.4%) and 40 children with upper airway obstruction (24 M; age: 7.5 ± 2.7 years; body mass index percentile: 65.8 ± 31.9%). We used the phase-averaging technique to compute respiratory sinus arrhythmia amplitude and phase delay. To study sleep stage effects and the effect of upper airway obstruction, respiratory sinus arrhythmia was measured during all artefact-free sleep episodes, and after exclusion of respiratory events. A significant increase in respiratory sinus arrhythmia amplitude and phase delay was observed during stage 4 sleep as compared with rapid eye movement sleep in both groups (amplitude: controls = 0.10 ± 0.03 versus 0.07 ± 0.02 s, < 0.01, respectively, and upper airway obstruction = 0.07 ± 0.03 versus 0.05 ± 0.03 s, < 0.05, respectively; phase delay: controls = 3.1 ± 0.1 versus 3.0 ± 0.1 rad, < 0.05, respectively, and upper airway obstruction = 3.13 ± 0.04 versus 3.04 ± 0.08 rad, < 0.01, respectively). A significant association between respiratory sinus arrhythmia and apnea/hypopnea index was observed during stage 2 sleep in children with upper airway obstruction. Compared with healthy controls, a significant decrease in respiratory sinus arrhythmia amplitude during stage 2 sleep was observed in children with upper airway obstruction (0.09 ± 0.03 versus 0.06 ± 0.03 s, < 0.05). However, this difference was not apparent when respiratory events were excluded from analysis. Importantly, respiratory sinus arrhythmia showed a strong negative correlation with body mass index. In conclusion, night-time respiratory sinus arrhythmia in children is sleep stage dependent and normal during quiet sleep in children with relatively mild upper airway obstruction.

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