Mitsis Georgios D, Poulin Marc J, Robbins Peter A, Marmarelis Vasilis Z
Department of Biomedical Engineering, University of Southern California, University Park, Los Angeles, CA 90089, USA.
IEEE Trans Biomed Eng. 2004 Nov;51(11):1932-43. doi: 10.1109/TBME.2004.834272.
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.
采用多输入非线性系统的拉盖尔 - 沃尔泰拉网络方法，研究了逐搏平均动脉血压波动和逐次呼吸末二氧化碳波动对逐搏脑血流速度变化的影响。对十名健康人体受试者进行实验测量后发现，尽管压力波动解释了大部分高频血流速度变化（高于0.04Hz），但呼气末二氧化碳波动以及压力与二氧化碳之间的非线性相互作用在较低频率（低于0.04Hz）时具有相当大的影响。研究结果还表明，脑自动调节具有强烈的非线性和动态性（频率依赖性）。非线性主要在低频范围（低于0.04Hz）起作用，并且在呼气末二氧化碳 - 血流速度关系的动态变化中更为突出。所得模型还揭示了显著的非平稳性，二氧化碳对血流速度动态变化的影响具有更大的变异性。
