Estimation of the correlation dimension of heart rate using surrogate data techniques.
Estimation of the correlation dimension of heart rate using surrogate data techniques.
复制标题
使用替代数据技术估计心率的相关维度。
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
S. A. Moulden
中科院分区：
文献类型：
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作者：
J. Thayer;S. A. Moulden
研究人员最近将非线性动力系统理论应用于生理时间序列数据。然而，用于估计相关维数的确定性方程的直接实现对于生理数据是有问题的。重要的是，非线性过程和噪声之间的区别是特别困难的实验数据。为帮助实现这种区分而开发的一种技术是使用替代数据。这些数据保留了原始时间序列的许多属性，但实际上是原始数据的随机化。然而，在足够高的嵌入空间中，非线性过程的相关维数的估计将趋于平稳，而噪声过程的这种估计将随着嵌入维数的增加而继续上升。在本实验中，检查了两个数据集。在自主呼吸和以每分钟15次呼吸起搏的呼吸期间从女性受试者收集心脏周期时间序列。两个数据集均由约3000个心搏间期组成，并检查了m = 2至m = 6的嵌入维数。结果表明，自主呼吸数据的相关维数估计达到了约4的平台，而该系列的替代数据显示没有这样的平台。对于起搏呼吸数据，原始数据和替代数据均未能显示相关维数估计值中的平台证据。这些结果表明，必须谨慎使用在解释有限值的关联维数作为证据的混沌吸引子在实验数据中，如果没有测试确定性进行。
Researchers have recently applied nonlinear dynamical systems theory to physiological time series data. However, the direct implementation of the deterministic equations used to estimate the correlation dimension is problematic for physiological data. Importantly, the distinction between a nonlinear process and noise is particularly difficult for experimental data. One technique that has been developed to help with this distinction is the use of surrogate data. These data preserve many of the properties of the original time series but in fact are a randomization of the original data. Whereas in a sufficiently high embedding space the estimates of the correlation dimension of a nonlinear process will plateau, such estimates for a noise process will continue to rise with increases in the embedding dimension. In the present experiment two data sets were examined. Heart period time series were collected from a female subject during spontaneous breathing and breathing paced at 15 breaths per minute. Both data sets consisted of approximately 3000 interbeat intervals and embedding dimensions of m = 2 through m = 6 were examined. Results indicate that the correlation dimension estimate for the spontaneous breathing data reached a plateau around 4, whereas the surrogate data for this series showed no such plateau. For the paced breathing data, both the original and the surrogate data failed to show evidence of a plateau in the estimates of the correlation dimension. These results suggest that caution must be used in interpreting finite values of correlation dimension as evidence of a chaotic attractor in experimental data if no test for determinism is performed.