Dynamic cerebral autoregulation during repeated squat-stand maneuvers
Dynamic cerebral autoregulation during repeated squat-stand maneuvers
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DOI：
10.1152/japplphysiol.90822.2008
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Zhang, Rong
中科院分区：
文献类型：
--
作者：
Claassen, Jurgen A. H. R.;Levine, Benjamin D.;Zhang, Rong
作者：张红，张红.反复蹲立动作时的动态脑自动调节。J Appl Physiol 106：153-160，2009.首次发表于2008年10月30日; doi：10.1152/japplphysiol.90822.2008。血压和脑血流量自发振荡的传递函数分析可以定量地反映血压和脑血流量之间的动态关系。然而，这样的振荡幅度通常很小并且具有可疑的临床意义，变化很大，并且不能控制。在非常低的频率（< 0.07 Hz），BP和CBF之间的相干性通常很低（< 0.50），它们之间的因果关系存在争议。8名健康受试者进行重复的蹲立动作，以诱导血压在0.025和0.05 Hz（极低频）和0.1 Hz（低频）的频率分别大的振荡。监测BP（Finapres）、CBF流速（CBFV;经颅多普勒）和潮气末CO2（二氧化碳描记法）。频谱分析用于量化BP和CBFV中的振荡，并估计传递函数相位、增益和相干性。与自发振荡相比，诱发振荡具有更高的相干性[平均值0.8（SD 0.11）;所有受试者在所有频率下均> 0.5]和更低的相位估计变异性。然而，收益估计保持不变。在这两种情况下，都观察到动态自动调节的“高通滤波”特征。总之，使用重复的蹲站动作，我们能够研究动态脑自动调节在低频率的条件下，血流动力学强和因果关系相关的振荡BP和CBFV。这不仅增强了传递函数分析的置信度，如高相干性和改进的相位估计所示，而且还增强了该方法的临床相关性，因为BP和CBFV中的诱导振荡模拟了与日常生活中的姿势变化相关的振荡。
Claassen JA, Levine BD, Zhang R. Dynamic cerebral autoregulation during repeated squat-stand maneuvers. J Appl Physiol 106: 153-160, 2009. First published October 30, 2008; doi: 10.1152/japplphysiol.90822.2008.-Transfer function analysis of spontaneous oscillations in blood pressure ( BP) and cerebral blood flow (CBF) can quantify the dynamic relationship between BP and CBF. However, such oscillation amplitudes are often small and of questionable clinical significance, vary substantially, and cannot be controlled. At the very low frequencies (< 0.07 Hz), coherence between BP and CBF often is low (< 0.50) and their causal relationship is debated. Eight healthy subjects performed repeated squat-stand maneuvers to induce large oscillations in BP at frequencies of 0.025 and 0.05 Hz ( very low frequency) and 0.1 Hz ( low frequency), respectively. BP (Finapres), CBF velocity (CBFV; transcranial Doppler), and end-tidal CO2 (capnography) were monitored. Spectral analysis was used to quantify oscillations in BP and CBFV and to estimate transfer function phase, gain, and coherence. Compared with spontaneous oscillations, induced oscillations had higher coherence [ mean 0.8 (SD 0.11); > 0.5 in all subjects at all frequencies] and lower variability in phase estimates. However, gain estimates remained unchanged. Under both conditions, the "high-pass filter" characteristics of dynamic autoregulation were observed. In conclusion, using repeated squat-stand maneuvers, we were able to study dynamic cerebral autoregulation in the low frequencies under conditions of hemodynamically strong and causally related oscillations in BP and CBFV. This not only enhances the confidence of transfer function analysis as indicated by high coherence and improved phase estimation but also strengthens the clinical relevance of this method as induced oscillations in BP and CBFV mimic those associated with postural changes in daily life.