Using Modified Sample Entropy to Characterize Aging-Associated Microvascular Dysfunction.

摘要: Cutaneous microvascular function can be assessed by skin blood flow (SBF) response to thermal stimuli. Usually, the activities of regulatory mechanisms are quantified means spectral analysis response. However, measures unable characterize nonlinear dynamics SBF signal. Sample entropy (SampEn) is a commonly used measure degree regularity time series. SampEn value depends on relationship between frequency studied and sampling rate. Hence, when series data oversampled, may give misleading results. We modified definition including lag successive points vectors compared address oversampled issue. The could chosen as first minimum auto mutual information tested performance using simulated signals in young old groups. results indicated that yields consistent for different rates data, but cannot. Blood showed higher during maximal vasodilation period baseline both groups older group group. Furthermore, our second peak more regular behavior oscillations (BFO) mainly attributed enhanced cardiac oscillations. This study suggests approach useful assessing function.