Influence of forced respiration on nonlinear dynamics in heart rate variability.

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Although it is doubtful whether the normal sinus rhythm can be described as low-dimensional chaos, there is evidence for inherent nonlinear dynamics and determinism in time series of consecutive R-R intervals. However, the physiological origin for these nonlinearities is unknown. The aim of this study was to test whether the known nonlinear input from spontaneous respiration is a source for the nonlinearities in heart rate variability. Twelve healthy subjects were examined in supine position with 3-h electrocardiogram recordings during both spontaneous and forced respiration in accordance with a metronome set to 12 min(-1). Nonlinear dynamics were measured as the correlation dimension and the nonlinear prediction error. Complexity expressed as correlation dimension was unchanged from normal respiration, 9.1 +/- 0.5, compared with forced respiration, 9.3 +/- 0.6. Also, nonlinear determinism expressed as the nonlinear prediction error did not differ between spontaneous respiration, 32.3 +/- 3.4 ms, and forced respiration, 31.9 +/- 5.7. It is concluded that the origin of the nonlinear dynamics in heart rate variability is not a nonlinear input from the respiration into the cardiovascular oscillator. Additional studies are needed to elucidate the mechanisms behind the nonlinear dynamics in heart rate variability.
Original languageEnglish
JournalAmerican Journal of Physiology (Consolidated)
Issue number4 Pt 2
Pages (from-to)R1149-54
Publication statusPublished - 1997

Bibliographical note

Keywords: Adolescent; Adult; Female; Heart Rate; Humans; Male; Middle Aged; Models, Biological; Nonlinear Dynamics; Respiration; Respiratory Mechanics; Supine Position; Time Factors

ID: 8420713