Wessel Niels, Gapelyuk Andrej, Weiß Jonas, Schmidt Martin, Kraemer Jan F, Berg Karsten, Malberg Hagen, Stepan Holger, Kurths Jürgen
Department of Physics, Humboldt-Universität zu Berlin, Berlin, Germany.
Institute of Biomedical Engineering, Technische Universität Dresden, Dresden, Germany.
Front Neurosci. 2020 Sep 24;14:547433. doi: 10.3389/fnins.2020.547433. eCollection 2020.
Spontaneous baroreflex sensitivity (BRS) is a widely used tool for the quantification of the cardiovascular regulation. Numerous groups use the xBRS method, which calculates the cross-correlation between the systolic beat-to-beat blood pressure and the R-R interval (resampled at 1 Hz) in a 10 s sliding window, with 0-5 s delays for the interval. The delay with the highest correlation is selected and, if significant, the quotient of the standard deviations of the R-R intervals and the systolic blood pressures is recorded as the corresponding xBRS value. In this paper we test the hypothesis that the xBRS method quantifies the causal interactions of spontaneous BRS from non-invasive measurements at rest. We use the term spontaneous BRS in the sense of the sensitivity curve is calculated from non-interventional, i.e., spontaneous, baroreceptor activity. This study includes retrospective analysis of 1828 measurements containing ECG as well as continues blood pressure under resting conditions. Our results show a high correlation between the heart rate - systolic blood pressure variability (HRV/BPV) quotient and the xBRS ( = 0.94, < 0.001). For a deeper understanding we conducted two surrogate analyses by substituting the systolic blood pressure by its reversed time series. These showed that the xBRS method was not able to quantify causal relationships between the two signals. It was not possible to distinguish between random and baroreflex controlled sequences. It appears xBRS rather determines the HRV/BPV quotient. We conclude that the xBRS method has a potentially large bias in characterizing the capacity of the arterial baroreflex under resting conditions. During slow breathing, estimates for xBRS are significantly increased, which clearly shows that measurements at rest only involve limited baroreflex activity, but does neither challenge, nor show the full range of the arterial baroreflex regulatory capacity. We show that xBRS is exclusively dominated by the heart rate to systolic blood pressure ratio ( = 0.965, < 0.001). Further investigations should focus on additional autonomous testing procedures such as slow breathing or orthostatic testing to provide a basis for a non-invasive evaluation of baroreflex sensitivity.
自发性压力反射敏感性（BRS）是一种广泛用于量化心血管调节的工具。许多研究团队使用xBRS方法，该方法在10秒的滑动窗口中计算逐搏收缩压与R-R间期（重采样至1Hz）之间的互相关，R-R间期有0-5秒的延迟。选择相关性最高的延迟，如果显著，则将R-R间期和收缩压的标准差之商记录为相应的xBRS值。在本文中，我们检验了这样一个假设，即xBRS方法能够通过静息状态下的非侵入性测量来量化自发性BRS的因果相互作用。我们使用“自发性BRS”一词，是指敏感性曲线是根据非介入性的，即自发性的压力感受器活动计算得出的。本研究包括对1828例静息状态下包含心电图以及连续血压测量数据的回顾性分析。我们的结果显示心率-收缩压变异性（HRV/BPV）商与xBRS之间存在高度相关性（r = 0.94，P < 0.001）。为了更深入地理解，我们进行了两项替代分析，即将收缩压用其时间反转序列替代。结果表明，xBRS方法无法量化两个信号之间的因果关系。无法区分随机序列和压力反射控制序列。似乎xBRS更多地是决定HRV/BPV商。我们得出结论，xBRS方法在表征静息状态下动脉压力反射能力时可能存在较大偏差。在慢呼吸期间，xBRS的估计值显著增加，这清楚地表明静息状态下的测量仅涉及有限的压力反射活动，既未对动脉压力反射进行挑战，也未显示其全部调节能力范围。我们表明xBRS完全由心率与收缩压之比主导（r = 0.965，P < 0.001）。进一步的研究应侧重于其他自主测试程序，如慢呼吸或直立位测试，以便为压力反射敏感性的非侵入性评估提供依据。
