Method for analyzing of dynamic cerebral autoregulation, and its significance : Comparable study and dynamic and static cerebral autoregulation on autoregulation curve.

1.数据采集：将5例成人志愿者的动脉压、经颅多普勒（TCD）测量的大脑中动脉（Vmca）血流速度和心电图同时通过AD转换器记录到PC上。动态脑自动调节（dCAR）分析新方法的建立：计算动脉压（MAP）和Vmca的逐拍平均值，在ECG各R峰处对齐，然后在0.5Hz处重新采样。利用MAP与平均Vmca之间的传递函数对dCAR进行分析。V计算相干性（coh）、增益和相位。高氧血症（PetCO_2: 50mmHg）时，coh <0.07Hz显著升高，正常氧血症（PetCO_2:30- 40mmhg）时，coh <0.07Hz趋于正常。以上结果提示，coh升高<0.07Hz可能是dcar的可靠指标。(1)动物实验：用激光多普勒测量5只成年猫的区域脑血流（rCBF），同时用TCD、ECG和MAP测量Vmca。采血、输血或输注苯肾上腺素诱导MAP（40,70,100,120和180mmHg）的逐步变化。在每个MAP保持稳定状态5min，并在每个MAP评估dCAR。在研究期间保持正常睡眠。(2)结果：平均Vmca和rCBF维持在MAP 70 ~ 120mmhg范围内，MAP为40mmHg时Vmca和rCBF均显著降低，MAP为180mmHg时Vmca和rCBF均升高（P<0.05）。与100mmHg时相比，MAP=40mmHg时<0.07Hz的coh显著升高，MAP=180mmHg时各频率的coh均显著升高（P<0.05）。结论：coh <07Hz升高与静态自调节功能受损程度有明显相关性。因此，床侧评价dCAR是可行和可靠的。

1.Data Acquisition :Arterial pressure, blood flow velocity in the middle cerebral artery(Vmca) measured with transcranial Doppler(TCD), and ECG were simultaneously recorded into PC via AD converter in 5 adult volunteers.2.Development of new method for analyzing of dynamic cerebral autoregulation(dCAR) :Beat by beat mean values of arterial pressure (MAP) and Vmca were calculated, aligned at each R peak of ECG, and then resampled at 0.5Hz. dCAR was analyzed with using transfer function between MAP and mean Vmca. V Coherence (coh), gain, and phase were calculated. During hypercpnia (PetCO_2>50mmHg), coh <0.07Hz was significantly increased, and normalized during normocapnia ((PetCO_2:30-40mmHg). These results indicate that an increase of coh <0.07Hz may be reliable indicator of dCAR.3.Evaluation of dCAR on static autoregulation curve :(1)Animal study : Regional CBF(rCBF) measured with laser Doppler, Vmca measured with TCD,ECG,and MAP were simultaneously measured in 5 adult cats. Stepwise changes of MAP(40,70,100,120,and 180mmHg) were induced by phlebotomy, transfusion, or an infusion of phenylephrine. Steady condition was maintained at each MAP for 5min, and dCAR was evaluated at each MAP. Normocapnia was maintained during study.(2)Results :mean Vmca and rCBF were maintained in the range of MAP between 70-120mmHg, and significantly reduced at MAP of 40mmHg, and increased at MAP of 180mmHg(P<0.05 in both). As compared at 100mmHg, coh in <0.07Hz was significantly increased at MAP=40mmHg, and coh in all frequency was significantly increased at MAP=180mmHg (P<0.05 in both).4.Conclusion :An increase of coh <07Hz can clearly correlate with degree of impairment of static autoregulation. Thus, bed side evaluation of dCAR is feasible and reliable.