Factors affecting the determination of cerebrovascular reactivity
Factors affecting the determination of cerebrovascular reactivity
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DOI：
10.1002/brb3.275
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发表时间：
2014-09-01
影响因子：
3.1
通讯作者：
Duffin, James
中科院分区：
文献类型：
--
作者：
Regan, Rosemary E.;Fisher, Joseph A.;Duffin, James
背景和目的：脑血管反应性 (CVR) 测量脑血管系统对 CO2 等血管活性刺激的反应能力。 CVR常表示为脑血流量变化与CO2变化的比值。我们研究了影响该测量的几个因素：血压、刺激模式、反应分析和受试者位置。方法：对九名受试者（坐位和仰卧位）进行阶梯式和斜坡式增加二氧化碳浓度。逐次呼吸测定大脑中动脉血流速度（MCAv）和平均动脉压（MAP）。脑血管传导率 (MCAc) 估计为 MCAv/MAP。 CVR 是根据 MCAc 和 MCAv 反应的相对和绝对测量值计算的。结果：某些受试者的 MAP 随 CO2 的增加而增加，因此根据电导响应计算出的相对 CVR 小于根据速度响应计算出的 CVR 计算出的相对 CVR。根据阶跃响应测量的 CVR 受到响应动态的影响，并且小于根据斜坡响应测量的 CVR 计算的值。受试者位置不影响 CVR。结论：（1）MAP随着CO2的增加而增加，并且是CVR测量的混杂因素； (2) CVR 取决于所使用的刺激模式； (3) 在这些实验中，坐位与仰卧位的 CVR 没有差异； (4)MCAv绝对变化计算的CVR小于相对变化计算的CVR。
Background and Purpose: Cerebrovascular reactivity (CVR), measures the ability of the cerebrovasculature to respond to vasoactive stimuli such as CO2. CVR is often expressed as the ratio of cerebral blood flow change to CO2 change. We examine several factors affecting this measurement: blood pressure, stimulus pattern, response analysis and subject position. Methods: Step and ramp increases in CO2 were implemented in nine subjects, seated and supine. Middle cerebral artery blood flow velocity (MCAv), and mean arterial pressure (MAP) were determined breath-by-breath. Cerebrovascular conductance (MCAc) was estimated as MCAv/MAP. CVR was calculated from both the relative and absolute measures of MCAc and MCAv responses. Results: MAP increased with CO2 in some subjects so that relative CVR calculated from conductance responses were less than those calculated from CVR calculated from velocity responses. CVR measured from step responses were affected by the response dynamics, and were less than those calculated from CVR measured from ramp responses. Subject position did not affect CVR. Conclusions: (1) MAP increases with CO2 and acts as a confounding factor for CVR measurement; (2) CVR depends on the stimulus pattern used; (3) CVR did not differ from the sitting versus supine in these experiments; (4) CVR calculated from absolute changes of MCAv was less than that calculated from relative changes.