Faculty of Medicine and Health Sciences, Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia.
Physiol Meas. 2017 Sep 21;38(10):N128-N137. doi: 10.1088/1361-6579/aa8981.
Cardio-ankle vascular index (CAVI) as measured using the VaSera device (CAVI, Fukuda Denshi), has been proposed as a stiffness index that does not depend on blood pressure. We have recently shown theoretically that CAVI still exhibits blood pressure dependence, and proposed the corrected index CAVI. The present study aims to establish a method of calculating [Formula: see text] either (i) from VaSera-reported values of cardiac-brachial and brachial-ankle pulse transit times (tb and tba, respectively) and blood pressure, or (ii) directly from CAVI. To derive this method, the relationship among CAVI and its scale constants a and b, tb, tba, and blood pressure has to be established.
From data of 497 subjects, eight candidate CAVI parameters were defined and calculated, containing all combinations of left or right tb/tba/blood pressure. Candidates were evaluated through correlation with measured left and right CAVI. Correlations were compared statistically. Once the correct candidates were determined, two constants (a and b) required for converting CAVI to CAVI were estimated through linear regression.
Left and right CAVI are calculated using left and right tba; however, both left and right CAVI are calculated using right brachial blood pressures and right tb. Constants a and b for conversion of CAVI to CAVI were estimated to be 0.842 [0.836 0.848] and 0.753 [0.721 0.786] (mean [95%CI]), respectively. Equations to estimate CAVI from CAVI, and to directly calculate CAVI from the VaSera output are provided in this paper, as well as in a directly usable spreadsheet supplement.
Our results permit straightforward calculation of [Formula: see text] during a study, as well as retrospective estimation of [Formula: see text] from CAVI in already published studies or where the original transit time values are not available, paving the way for thorough comparison of CAVI to CAVI in clinical and research settings. Novelty and significance Cardio-ankle vascular index (CAVI) as measured using the VaSera device (CAVI, Fukuda Denshi), has been proposed as a blood pressure-independent arterial stiffness index. We have recently shown theoretically that CAVI still exhibits pressure dependence, and proposed a corrected index, CAVI. In the present study, we derived equations to directly obtain CAVI using data from the VaSera device. Our results permit straightforward calculation of [Formula: see text] during a study, as well as retrospective estimation of [Formula: see text] from CAVI in already published studies, paving the way for thorough comparison of CAVI to CAVI in clinical and research settings.
使用 VaSera 设备（CAVI，Fukuda Denshi）测量的心血管踝指数（CAVI）被提出作为一种不依赖血压的僵硬指数。我们最近从理论上证明，CAVI 仍然表现出血压依赖性，并提出了校正指数 CAVI。本研究旨在建立一种计算[公式：见正文]的方法，要么（i）从 VaSera 报告的心脏-臂和臂-踝脉搏传输时间（tb 和 tba，分别）和血压中计算，要么（ii）直接从 CAVI 中计算。为了推导出这种方法，必须建立 CAVI 与其标度常数 a 和 b、tb、tba 和血压之间的关系。
从 497 名受试者的数据中，定义并计算了 8 个候选 CAVI 参数，包含左或右 tb/tba/血压的所有组合。通过与测量的左和右 CAVI 的相关性来评估候选者。通过统计学比较相关性。一旦确定了正确的候选者，就通过线性回归估计将 CAVI 转换为 CAVI 所需的两个常数（a 和 b）。
左和右 CAVI 使用左和右 tba 计算；然而，左和右 CAVI 都使用右肱动脉血压和右 tb 计算。转换 CAVI 为 CAVI 的常数 a 和 b 估计为 0.842 [0.836-0.848] 和 0.753 [0.721-0.786]（平均值[95%CI]）。本文以及一个可直接使用的电子表格补充中提供了从 CAVI 估计 CAVI 的方程，以及直接从 VaSera 输出计算 CAVI 的方程。
我们的结果允许在研究期间直接计算[公式：见正文]，以及从已发表的研究或原始传输时间值不可用的情况下从 CAVI 中回溯估计[公式：见正文]，为在临床和研究环境中彻底比较 CAVI 与 CAVI 铺平了道路。
使用 VaSera 设备（CAVI，Fukuda Denshi）测量的心血管踝指数（CAVI）被提出作为一种不依赖血压的动脉僵硬指数。我们最近从理论上证明，CAVI 仍然表现出血压依赖性，并提出了校正指数 CAVI。在本研究中，我们推导出了使用 VaSera 设备数据直接获得 CAVI 的方程。我们的结果允许在研究期间直接计算[公式：见正文]，以及从已发表的研究中的 CAVI 回溯估计[公式：见正文]，为在临床和研究环境中彻底比较 CAVI 与 CAVI 铺平了道路。
