Coherent averaging of pseudorandom binary stimuli: is the dynamic cerebral autoregulatory response symmetrical?
Coherent averaging of pseudorandom binary stimuli: is the dynamic cerebral autoregulatory response symmetrical?
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DOI：
10.1088/1361-6579/aa9086
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发表时间：
2017-12-01
影响因子：
3.2
通讯作者：
Panerai, Ronney B.
中科院分区：
文献类型：
--
作者：
Katsogridakis, Emmanuel;Simpson, David M.;Panerai, Ronney B.
目的：对脑自调节的研究表明，脑半球对称性的存在可能在脑卒中和创伤性脑损伤中发生改变。然而，关于引起脑高灌注的干扰与引起脑低灌注的干扰之间的反应是否对称的数据缺乏。我们的目的是探讨脑自动调节对不同方向血流动力学刺激的反应是否对称。方法：使用先前描述的评估方法，我们采用连贯平均脑血流速度（CBFV）对大腿袖膨胀和收缩的反应，由伪随机二值序列驱动，同时改变吸入的二氧化碳。自调节反应的对称性是根据其速度和增益两个参数来评估的。采用一阶谐波法估计临界闭合压（CrCP）和阻力面积积（RAP），并通过动脉血压（ABP）与CBFV、ABP与CrCP、最终ABP与RAP的相干平均值进行线性回归计算自调节反应增益。采用双向重复测量方差分析评估ABP变化方向和CO2给药方法的影响。主要结果：我们的研究结果表明，虽然ABP变化的方向没有显著影响，但CO2给药方式的影响非常显著（p < 10(-4)）。意义：这是首次报道间歇性和持续性高碳酸血症下RAP和CrCP对不同方向刺激的自调节反应的对称性以及短期动态。由于血流动力学刺激方向似乎没有影响，我们的研究结果验证了以前使用不同评估方法所做的工作。
Objective: Previous studies on cerebral autoregulation have shown the existence of hemispheric symmetry, which may be altered in stroke and traumatic brain injury. There is a paucity of data however on whether the response is symmetrical between those disturbances that cause cerebral hyperperfusion, to those that cause hypoperfusion. Our aim was to investigate whether the responses of cerebral autoregulation to haemodynamic stimuli of different directions are symmetrical. Approach: Using a previously described assessment method, we employed coherent averaging of the cerebral blood flow velocity (CBFV) responses to thigh cuff inflation and deflation, as driven by pseudorandom binary sequences, whilst simultaneously altering the inspired CO2. The symmetry of the autoregulatory response was assessed with regards to two parameters, its speed and gain. Using the first harmonic method, critical closing pressure (CrCP) and resistance area product (RAP) were estimated, and the gain of the autoregulatory response was calculated by performing linear regression between the coherent averages of arterial blood pressure (ABP) and CBFV, ABP and CrCP and finally ABP and RAP. A two-way repeated measures ANOVA was used to assess for the effect of the direction of change in ABP and the method of CO2 administration. Main results: Our results suggest that whilst the direction of ABP change does not have a significant effect, the effect of CO2 administration method is highly significant (p < 10(-4)). Significance: This is the first report to demonstrate the symmetry of the autoregulatory response to stimuli of different directions as well as the short term dynamics of RAP and CrCP under intermittent and constant hypercapnia. As haemodynamic stimulus direction does not appear to have an influence, our findings validate previous work done using different assessment methods.