Title :
Nonlinear analysis of dynamic cerebral autoregulation in humans under orthostatic stress
Author :
Mitsis, Georgios D. ; Mahalingam, Aarthi ; Zhang, Rong ; Levine, Benjamin D. ; Marmarelis, Vasilis Z.
Author_Institution :
Dept. of Biomed. Eng., Univ. of Southern California, Los Angeles, CA, USA
Abstract :
The effects of orthostatic stress on cerebral autoregulation are assessed by examining the dynamic relationship between spontaneous fluctuations of cerebral blood flow and arterial blood pressure under various levels of Lower Body Negative Pressure (LBNP) in healthy humans. The Laguerre-Volterra network methodology for modeling nonlinear systems is employed to this purpose. Results are obtained in the form of Volterra kernels as well as in the form of the dynamic modes of the system. Three significant modes are identified, one of them residing mostly in the linear system dynamics, and the other two residing in the nonlinear system dynamics. The obtained results reveal that the latter are affected mainly in the low frequency range (below 0.04 Hz), whereas they remain unaffected in the intermediate frequency range (between 0.04 and 0.08 Hz) and are affected moderately above 0.08 Hz.
Keywords :
brain models; haemodynamics; haemorheology; nonlinear dynamical systems; 0.04 to 0.08 Hz; Laguerre-Volterra network methodology; Volterra kernels; arterial blood pressure; cerebral blood flow; dynamic cerebral autoregulation nonlinear analysis; healthy humans; lower body negative pressure; nonlinear system dynamics; nonlinear systems modeling; orthostatic stress; spontaneous fluctuations; Arterial blood pressure; Biological system modeling; Blood flow; Fluctuations; Frequency; Humans; Kernel; Nonlinear dynamical systems; Nonlinear systems; Stress;
Conference_Titel :
Engineering in Medicine and Biology Society, 2003. Proceedings of the 25th Annual International Conference of the IEEE
Print_ISBN :
0-7803-7789-3
DOI :
10.1109/IEMBS.2003.1279685
