Nonlinear physiological systems identification: Application to cerebral hemodynamics under orthostatic stress

Georgios D. Mitsis, Rong Zhang, Benjamin D. Levine, Vasilis Z. Marmarelis

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The effects of orthostatic stress, induced by lower body negative pressure (LBNP), on cerebral hemodynamics were examined in a nonlinear context. Spontaneous fluctuations of beat-to-beat mean arterial blood pressure (MABP) in the finger, mean cerebral blood flow velocity (MCBFV) in the middle cerebral artery, as well as breath-by-breath endtidal CO2 concentration (PETCO2) were measured continuously in ten healthy subjects under resting conditions and during graded LBNP to presyncope. A two-input nonlinear Laguerre-Volterra network model was employed to study the dynamic effects of MABP and PETCO2 changes, as well as their nonlinear interactions, on MCBFV variations in the very low (VLF; below 0.04 Hz), low (LF; 0.04-0.15 Hz) and high frequency (HF; 0.15-0.30 Hz) ranges. Dynamic cerebral autoregulation was described by the model terms corresponding to MABP, while cerebral vasomotor reactivity was described by the model PETCO2 terms. The magnitude of the linear and nonlinear MABP-MCBFV Volterra kernels increased substantially above -30 mm Hg LBNP in the VLF range, implying impaired dynamic autoregulation. In contrast, the magnitude of the PETCO2-MCBFV kernels reduced during LBNP at all frequencies, suggesting attenuated cerebral vasomotor reactivity. These changes may reflect a progressively more unstable circulation that could ultimately lead to cerebral hypoperfusion and syncope.

Original languageEnglish (US)
Title of host publicationProceedings of the 7th International Workshop on Mathematical Methods in Scattering Theory and Biomedical Engineering
PublisherWorld Scientific Publishing Co. Pte Ltd
Pages362-369
Number of pages8
ISBN (Print)9812568603, 9789812568601
Publication statusPublished - 2006
Event2005 7th International Workshop on Mathematical Methods on Scattering Theory and Biomedical Engineering - Nymphaio, Greece
Duration: Sep 8 2005Sep 11 2005

Other

Other2005 7th International Workshop on Mathematical Methods on Scattering Theory and Biomedical Engineering
CountryGreece
CityNymphaio
Period9/8/059/11/05

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ASJC Scopus subject areas

  • Biomedical Engineering
  • Applied Mathematics

Cite this

Mitsis, G. D., Zhang, R., Levine, B. D., & Marmarelis, V. Z. (2006). Nonlinear physiological systems identification: Application to cerebral hemodynamics under orthostatic stress. In Proceedings of the 7th International Workshop on Mathematical Methods in Scattering Theory and Biomedical Engineering (pp. 362-369). World Scientific Publishing Co. Pte Ltd.