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首页> 外文期刊>Journal of Clinical Ultrasound: JCU >Peak and time-integrated shear rates independently predict flow-mediated dilation
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Peak and time-integrated shear rates independently predict flow-mediated dilation

机译：峰值和时间积分剪切速率独立预测流量介导的扩张

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Background: To determine whether peak and time-integrated shear rates independently predict flow-mediated dilation (FMD). Methods: Eleven physically active (25±5 years old) male subjects were tested. FMD was defined as the shear rate-diameter relationship. Hierarchical linear modeling was used to estimate brachial artery diameter change with repeated measures of shear rate nested within each subject. Two models were tested: 1) FMD was induced using ischemia-induced hyperemia (2, 4, 6, and 10 minutes); and 2) FMD was induced following transient (ischemia) and steady-state (forearm heating and handgrip exercise) increases in shear rate. For both models we determined whether peak, in addition to time-integrated shear rates, explained a significant portion of variation for diameter change. Results: Model 1: Time integrated shear rates explained most of the variation for diameter change. However, peak shear rate explained an additional significant portion of variation. Model 2: The transient condition resulted in significantly (p = 0.012) smaller diameter change per shear rate change than the steady-state condition. However, when specifying peak shear rate as a covariate, the difference between conditions became nonsignificant (p = 0.138). Conclusions: Peak and time-integrated shear rates independently predict FMD. Future studies using the FMD test should consider both parameters.
机译：背景：为了确定峰值和时间积分剪切速率是否独立地预测流动介导的膨胀（FMD）。方法：对11名身体活动（25±5岁）的男性受试者进行了测试。 FMD定义为剪切速率-直径关系。使用分层线性建模来估计肱动脉直径的变化，并重复嵌套在每个受试者体内的剪切速率测量值。测试了两个模型：1）使用缺血性充血（2、4、6和10分钟）诱导FMD; 2）短暂（局部缺血）和稳态（前臂加热和握力练习）剪切速率增加后诱发FMD。对于这两个模型，我们确定除时间积分剪切速率外，峰是否解释了直径变化的显着部分。结果：模型1：时间积分剪切率解释了直径变化的大部分变化。但是，峰值剪切速率说明了变化的另一个重要部分。模型2：瞬态条件导致每个剪切速率变化的直径变化比稳态条件小得多（p = 0.012）。但是，将峰值剪切速率指定为协变量时，条件之间的差异变得不显着（p = 0.138）。结论：峰值和时间积分剪切速率独立地预测FMD。未来使用FMD测试的研究应考虑这两个参数。

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