Panerai R B, Kelsall A W, Rennie J M, Evans D H
Division of Medical Physics, University of Leicester, Leicester Royal Infirmary, UK.
IEEE Trans Biomed Eng. 1996 Aug;43(8):779-88. doi: 10.1109/10.508541.
The dynamic response of cerebral autoregulation to spontaneous changes in arterial blood pressure (ABP) is described by the relationship between cerebral blood flow velocity (CBFV) and resistance-area product (RAP). CBFV was measured with Doppler ultrasound in the middle cerebral artery and ABP with an intra-arterial catheter in 66 neonates. Spontaneous changes in mean ABP were automatically detected and the maximum derivative was used to synchronize the coherent averaging of corresponding CBFV and RAP transients. These were classified into two groups corresponding to intact (group A) or impaired (group B) autoregulation. The cross correlation between RAP and CBFV indicates a significant relationship with a time delay of 5 s for group A. The frequency response of RAP was estimated by the cross spectra with CBFV. Groups A and B present a similar amplitude spectra but the phase spectra of group A lags that of group B. The impulse responses of the two groups are also markedly different and were used to simulate the velocity response to a 5% step change in ABP. Impulse responses were also obtained for four different levels of pCO2 showing that hypercapnia leads to an impulse response similar to that of group B (impaired autoregulation). This method can be used to extend the usual dichotomic classification adopted in clinical studies of autoregulation.
脑自动调节对动脉血压（ABP）自发变化的动态反应通过脑血流速度（CBFV）与阻力-面积乘积（RAP）之间的关系来描述。在66例新生儿中，使用多普勒超声测量大脑中动脉的CBFV，并通过动脉内导管测量ABP。自动检测平均ABP的自发变化，并使用最大导数来同步相应CBFV和RAP瞬变的相干平均。这些被分为两组，分别对应完整（A组）或受损（B组）的自动调节。RAP与CBFV之间的互相关表明A组在5秒的时间延迟时有显著关系。通过与CBFV的交叉谱估计RAP的频率响应。A组和B组呈现相似的幅度谱，但A组的相位谱落后于B组。两组的脉冲响应也明显不同，并用于模拟对ABP 5%阶跃变化的速度响应。还获得了四种不同pCO2水平的脉冲响应，表明高碳酸血症导致的脉冲响应与B组（自动调节受损）相似。该方法可用于扩展自动调节临床研究中通常采用的二分法分类。
