Panerai R B, Simpson D M, Deverson S T, Mahony P, Hayes P, Evans D H
Division of Medical Physics, Faculty of Medicine, University of Leicester, U.K.
IEEE Trans Biomed Eng. 2000 Mar;47(3):419-23. doi: 10.1109/10.827312.
The contributions of beat-to-beat changes in mean arterial blood pressure (MABP) and breath-by-breath fluctuations in end-tidal CO2 (EtCO2) as determinants of the spontaneous variability of cerebral blood flow velocity (CBFV) were studied in 16 normal subjects at rest. The two input variables (MABP and EtCO2) had significant cross-correlations with CBFV but not between them. Transfer functions were estimated as the multivariate least mean square finite impulse response causal filters. MABP showed a very significant effect in explaining CBFV variability (p < 10(-11), Fisher's aggregated-p test) and the model mean square error was significantly reduced (p < 0.001) by also including the contribution of EtCO2. The estimated mean CBFV step response to MABP displayed the characteristic return to baseline caused by the cerebral autoregulatory response. The corresponding response to EtCO2 showed a gradual rise taking approximately 10 s to reach a plateau of 2.5%/mmHg. This study demonstrated that spontaneous fluctuations in EtCO2 can help to explain the CBFV variability at rest if appropriate signal processing techniques are employed to address the limited power and bandwith of the breath-by-breath EtCO2 signal.
在16名静息状态的正常受试者中，研究了平均动脉血压（MABP）的逐搏变化和呼气末二氧化碳（EtCO2）的逐次呼吸波动作为脑血流速度（CBFV）自发变异性决定因素的作用。两个输入变量（MABP和EtCO2）与CBFV有显著的互相关性，但它们之间没有。传递函数被估计为多元最小均方有限脉冲响应因果滤波器。MABP在解释CBFV变异性方面显示出非常显著的作用（p < 10(-11)，Fisher综合p检验），并且通过纳入EtCO2的贡献，模型均方误差显著降低（p < 0.001）。估计的CBFV对MABP的平均阶跃响应显示出由脑自动调节反应引起的特征性基线恢复。对EtCO2的相应响应显示出逐渐上升，大约需要10秒达到2.5%/mmHg的平台期。这项研究表明，如果采用适当的信号处理技术来处理逐次呼吸EtCO2信号的有限功率和带宽，EtCO2的自发波动有助于解释静息状态下的CBFV变异性。
