Annu Int Conf IEEE Eng Med Biol Soc. 2021 Nov;2021:5582-5585. doi: 10.1109/EMBC46164.2021.9629476.
Fixed sample entropy (fSampEn) is a promising technique for the analysis of respiratory electromyographic (EMG) signals. Its use has shown outperformance of amplitude-based estimators such as the root mean square (RMS) in the evaluation of respiratory EMG signals with cardiac noise and a high correlation with respiratory signals, allowing changes in respiratory muscle activity to be tracked. However, the relationship between the fSampEn response to a given muscle activation has not been investigated. The aim of this study was to analyze the nature of the fSampEn measurements that are produced as the EMG activity increases linearly. Simulated EMG signals were generated and increased linearly. The effect of the parameters r and the size of the moving window N of the fSampEn were evaluated and compared with those obtained using the RMS. The RMS showed a linear trend throughout the study. A non-linear, sigmoidal-like behavior was found when analyzing the EMG signals using the fSampEn. The lower the values of r, the higher the non-linearity observed in the fSampEn results. Greater moving windows reduced the variation produced by too small values of r.Clinical Relevance- Understanding the inherent non-linear relationship produced when using the fSampEn in EMG recordings will contribute to the improvement of the respiratory muscle activation assessment at different levels of respiratory effort in patients with respiratory conditions, particularly during the inspiratory phase.
固定样本熵（fSampEn）是一种很有前途的分析呼吸肌电图（EMG）信号的技术。其在评估存在心脏噪声的呼吸 EMG 信号时，表现优于基于幅度的估计量，如均方根（RMS），并且与呼吸信号高度相关，能够跟踪呼吸肌活动的变化。然而，尚未研究给定肌肉激活时 fSampEn 响应的关系。本研究的目的是分析随着 EMG 活动线性增加而产生的 fSampEn 测量的性质。生成模拟的 EMG 信号并使其线性增加。评估 fSampEn 的参数 r 和移动窗口 N 的大小的影响，并将其与 RMS 获得的结果进行比较。RMS 在整个研究中表现出线性趋势。在用 fSampEn 分析 EMG 信号时，发现了一种非线性、类正弦的行为。r 的值越低，fSampEn 结果中的非线性观察值越高。较大的移动窗口减少了 r 的过小值产生的变化。临床意义-了解在 EMG 记录中使用 fSampEn 时产生的固有非线性关系，将有助于改善呼吸状况患者在不同呼吸努力水平下的呼吸肌激活评估，特别是在吸气阶段。
