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Title: Estimating cardiac autonomic activity during sleep: impedance cardiography, spectral analysis, and Poincare plots
Author(s): H.J. Burgess, P.D. Penev, R. Schneider and Van Cauter E.
Journal: Clin.Neurophysiol.
Year: 2004
Volume: 115
Issue: 1
Pages: 19--28
Publisher address: Research Laboratory on Sleep, Chronobiology and Neuroendocrinology, Section of Endocrinology, Department of Medicine, University of Chicago, Chicago, IL, USA.
File URL: vuams-pubs/Burgess_2004.pdf
Keywords: Adult, analysis, Autonomic Nervous System, blood, Blood Pressure, Cardiography,Impedance, Data Interpretation,Statistical, Heart, Heart Rate, Humans, innervation, Male, methods, physiology, Pressure, Sleep, Sleep,Rem
Abstract: OBJECTIVE: To compare noninvasive measures of cardiac autonomic activity during sleep. METHODS: The absolute and normalized (n.u.) high and low frequency peaks from the spectral analysis of R-R intervals (HF, LF, HFn.u., LFn.u.), LF/HF ratio, pre-ejection period (PEP) from impedance cardiography, and the autocorrelation coefficient (rRR) as illustrated in Poincare plots were measured during night-time sleep in 9 young healthy subjects. Heart rate and blood pressure were also recorded. RESULTS: Heart rate was significantly associated with cardiac sympathetic activity (PEP, average r=-0.46), but not with cardiac parasympathetic activity (HF, average r=-0.17). rRR was significantly associated with heart rate (average r=0.41), and LF/HF (average r=0.69), but not with PEP or HF. From NREM to REM sleep, heart rate, LFn.u., LF and rRR significantly increased, HFn.u. significantly decreased, LF/HF showed an increasing trend (P=0.07) and PEP showed a decreasing trend (P=0.06). Blood pressure and HF were highly variable without significant changes from NREM to REM sleep. CONCLUSIONS: Cardiac parasympathetic activity (HF) does not vary greatly between sleep stages. Cardiac sympathetic activity (PEP) decreases linearly during sleep. rRR and LF/HF can track sympathovagal changes during sleep, but cannot differentiate between changes in cardiac parasympathetic and sympathetic activity. The relative advantages and disadvantages of the different measures are discussed

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