The influence of calculation method on estimates of cerebral critical closing pressure
The influence of calculation method on estimates of cerebral critical closing pressure
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DOI：
10.1088/0967-3334/32/4/007
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发表时间：
2011-04-01
影响因子：
3.2
通讯作者：
Robinson, T. G.
中科院分区：
文献类型：
--
作者：
Panerai, R. B.;Salinet, A. S. M.;Robinson, T. G.
脑循环的临界闭合压（CrCP）通常是通过瞬时速度-压力曲线外推来估计的。分析了不同的估计方法，以评估其在静态和动态应用中的鲁棒性和可重复性。10名健康受试者（平均+/- SD年龄37.5 +/- 9.2岁）静息时连续记录动脉血压（BP, Finapres）和双侧脑血流速度（经颅多普勒超声，大脑中动脉）。每次录音由三个独立的5分钟录音组成。在两周的时间内，每个受试者总共进行了四次录音。总共117个记录包含34 014个心动周期。对于每个心动周期，使用线性回归（LR）、主成分分析（PCA）、一次谐波拟合（H1）、2点收缩期/舒张期值（2Ps）和2点平均/舒张期值（2Pm）估计CrCP和阻力面积积（RAP）。LR和PCA也只应用于舒张期（LRd, PCAd）。与其他方法相反，LRd、PCAd、H1和2Pm在整个5分钟记录（“静态”条件）中的CrCP和RAP平均值没有显著差异。同样的四种方法在CrCP不存在负值和受试者内平均标准误差变异系数（CV） （SEM）方面的结果最好。另一方面，“动态”应用，如平均BP和RAP之间的传递函数（相干性和RAP阶跃响应）导致了不同方法的排名，但CV SEM相干性没有显著差异。对于RAP阶跃响应的CV， LRd和PCAd表现不佳。这些结果表明，H1或2Pm比LR分析效果更好，应该用于估算静态和动态应用的CrCP和RAP。
The critical closing pressure (CrCP) of cerebral circulation is normally estimated by extrapolation of instantaneous velocity-pressure curves. Different methods of estimation were analysed to assess their robustness and reproducibility in both static and dynamic applications. In ten healthy subjects (mean +/- SD age 37.5 +/- 9.2 years) continuous recordings of arterial blood pressure (BP, Finapres) and bilateral cerebral blood flow velocity (transcranial Doppler ultrasound, middle cerebral arteries) were obtained at rest. Each session consisted of three separate 5 min recordings. A total of four recording sessions for each subject took place over a 2 week period. A total of 117 recordings contained 34 014 cardiac cycles. For each cardiac cycle, CrCP and resistance-area product (RAP) were estimated using linear regression (LR), principal component analysis (PCA), first harmonic fitting (H1), 2-point systolic/diastolic values (2Ps) and 2-point mean/diastolic values (2Pm). LR and PCA were also applied using only the diastolic phase (LRd, PCAd). The mean values of CrCP and RAP for the entire 5 min recording ('static' condition) were not significantly different for LRd, PCAd, H1 and 2Pm, as opposed to the other methods. The same four methods provided the best results regarding the absence of negative values of CrCP and the coefficient of variation (CV) of the intra-subject standard error of the mean (SEM). On the other hand, 'dynamic' applications, such as the transfer function between mean BP and RAP (coherence and RAP step response) led to a different ranking of methods, but without significant differences in CV SEM coherence. For the CV of the RAP step response though, LRd and PCAd performed badly. These results suggest that H1 or 2Pm perform better than LR analysis and should be used for the estimation of CrCP and RAP for both static and dynamic applications.