Differentiation of the functional from the structural vascular tone using new elasticity indices of the linger artery and their psychophysiological application

采用810nm波长的近红外手指光体积图提供了在正常（I：组织加血液）和缺血循环状态（I_t：仅组织）下叠加在透射直流成分上的脉动ac成分（ΔI）。同时记录徘徊血压提供了扩张脉搏（PP）和平均血压（MBP）。根据朗伯特-比尔定律，建议动脉顺应性指标CI = ΔI/I/PP。我们引入了指数压力-体积模型（V=a-b×exp(-nP)），并检查了血管张力的功能和结构变化对这些参数的影响。实验1:12名女性受试者将对侧手浸泡在两种不同温度（44℃，22℃）的水中。在22℃条件下，对数CI和MBP之间的线性回归计算CI在9OmmHg（CI90）时显著下降。实验2：采用心算时的linger-occlusion方法对16例女性和5例反应性充血进行了CI跨壁压功能关系的研究。对数变换后的CI与跨壁压力呈线性相关。在指数模型的三个参数中，参数a的变化最为一致。实验三：考察了31名青年学生和9名中年工人在静息状态下参数a、b、n的年龄相关差异。与青年学生相比，中年被试的模型适应度下降，只有参数n降低。参数n与衡量动脉硬度的肱-踝脉波速度（baPWV）显著相关。用近红外光谱法记录腕部桡动脉反应性充血时的血流介导扩张（FMD）。青年组FMD发病高峰时间较中老年组延迟，且与baPWV呈负相关。

A near-infrared finger photoplethysmogram adopting a wavelength of 810nm provides for the pulsatile ac component(ΔI) superimposed on the transmitted dc components in a normal (I:tissue plus blood) and an ischemic circulatory state (I_t:tissue only). Simultaneous recording of linger blood pressure provides for the distending pulse(PP) and mean blood pressure(MBP). Based on the Lambert Beer's law, indices of the arterial compliance (CI;= ΔI/I/PP) is advocated for the linger vasculature. We introduced the exponential pressure-volume model(V=a-b×exp(-nP)) and examined the effects of functional and structural variations in the vascular tone on these parameters. Experiment 1:Twelve female subjects underwent immersions of the contralateral hand in water at two different temperatures(44℃,22℃). CI calculated at 9OmmHg(CI90) of linear regression between log CI and MBP decreased significantly during 22℃ condition. Experiment 2:The functional relationship to the transmural pressure for CI was examined using linger-occlusion during mental arithmetics in sixteen females and reactive hyperemia in five. Logarithmically transformed CI was linearly associated with the transmural pressure. Changes in parameter a were most consistent among three parameters of the exponential model. Experiment 3:Age-associated differences in parameter a,b, and n were examined during resting condition between 31 young students and 9 middle aged workers. In the middle aged subjects, the model fitness deteriorated and only the parameter n was lowered compared with the young student. Parameter n was significantly correlated with brachial-ankle pulse wave velocity(baPWV) as a measure of arterial stiffness. Flow-mediated dilation(FMD) during reactive hyperemia at the wrist radial artery was recorded by oxygenated hemoglobin using near-infrared spectroscopy. Peak time of FMD was delayed in the young group as compared with the middle aged group and negatively correlated with baPWV.