Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, United States of America.
PLoS One. 2019 Feb 12;14(2):e0211710. doi: 10.1371/journal.pone.0211710. eCollection 2019.
We report a study on twenty-two healthy human subjects of the dynamic relationship between cerebral hemoglobin concentration ([HbT]), measured with near-infrared spectroscopy (NIRS) in the prefrontal cortex, and systemic arterial blood pressure (ABP), measured with finger plethysmography. [HbT] is a measure of local cerebral blood volume (CBV). We induced hemodynamic oscillations at discrete frequencies in the range 0.04-0.20 Hz with cyclic inflation and deflation of pneumatic cuffs wrapped around the subject's thighs. We modeled the transfer function of ABP and [HbT] in terms of effective arterial (K(a)) and venous (K(v)) compliances, and a cerebral autoregulation time constant (τ(AR)). The mean values (± standard errors) of these parameters across the twenty-two subjects were K(a) = 0.01 ± 0.01 μM/mmHg, K(v) = 0.09 ± 0.05 μM/mmHg, and τ(AR) = 2.2 ± 1.3 s. Spatially resolved measurements in a subset of eight subjects reveal a spatial variability of these parameters that may exceed the inter-subject variability at a set location. This study sheds some light onto the role that ABP and cerebral blood flow (CBF) play in the dynamics of [HbT] measured with NIRS, and paves the way for new non-invasive optical studies of cerebral blood flow and cerebral autoregulation.
我们报告了一项在 22 名健康人体受试者中进行的研究，研究了前额叶皮层近红外光谱（NIRS）测量的脑血红蛋白浓度（[HbT]）与手指体积描记法测量的系统动脉血压（ABP）之间的动态关系。[HbT]是局部脑血容量（CBV）的度量。我们通过周期性地充气和放气包裹在受试者大腿上的气动袖带，在 0.04-0.20 Hz 的离散频率范围内诱导血流动力学振荡。我们根据有效动脉（K(a)）和静脉（K(v)）顺应性以及脑自动调节时间常数（τ(AR)），对 ABP 和 [HbT] 的传递函数进行建模。这 22 名受试者的这些参数的平均值（±标准误差）为 K(a)=0.01±0.01μM/mmHg、K(v)=0.09±0.05μM/mmHg 和 τ(AR)=2.2±1.3s。在 8 名受试者的子集的空间分辨测量中，发现这些参数的空间变异性可能超过特定位置的个体间变异性。这项研究揭示了 ABP 和脑血流量（CBF）在 NIRS 测量的 [HbT]动力学中所起的作用，并为新的非侵入性光学脑血流和脑自动调节研究铺平了道路。
