Nonlinear modeling of the dynamic effects of arterial pressure and CO2 variations on cerebral blood flow in healthy humans.
The effect of spontaneous beat-to-beat mean arterial blood pressure fluctuations and breath-to-breath end-tidal CO2 fluctuations on beat-to-beat cerebral blood flow velocity variations is studied using the Laguerre-Volterra network methodology for multiple-input nonlinear systems. The observations made from experimental measurements from ten healthy human subjects reveal that, whereas pressure fluctuations explain most of the high-frequency blood flow velocity variations (above 0.04 Hz), end-tidal CO2 fluctuations as well as nonlinear interactions between pressure and CO2 have a considerable effect in the lower frequencies (below 0.04 Hz). They also indicate that cerebral autoregulation is strongly nonlinear and dynamic (frequency-dependent). Nonlinearities are mainly active in the low-frequency range (below 0.04 Hz) and are more prominent in the dynamics of the end-tidal CO2-blood flow velocity relationship. Significant nonstationarities are also revealed by the obtained models, with greater variability evident for the effects of CO2 on blood flow velocity dynamics.
Mitsis
Georgios D
GD
Department of Biomedical Engineering, University of Southern California, University Park, Los Angeles, CA 90089, USA. gmitsis@bmsr.usc.edu
Poulin
Marc J
MJ
Robbins
Peter A
PA
Marmarelis
Vasilis Z
VZ
D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001921:Brain / Q000098:blood supply* / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology; D003198:Computer Simulation; D006801:Humans; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D013223:Statistics as Topic
D002245:Carbon Dioxide