IEEE Trans Biomed Eng. 2018 May;65(5):1049-1056. doi: 10.1109/TBME.2017.2737328. Epub 2017 Aug 7.
This study investigates the time-dependent behaviour and algorithmic complexity of low-frequency periodic oscillations in blood flux (BF) and oxygenation signals from the microvasculature.
Microvascular BF and oxygenation (OXY: oxyHb, deoxyHb, totalHb, and SO%) was recorded from 15 healthy young adult males using combined laser Doppler fluximetry and white light spectroscopy with local skin temperature clamped to 33 °C and during local thermal hyperaemia (LTH) at 43 °C. Power spectral density of the BF and OXY signals was evaluated within the frequency range (0.0095-1.6 Hz). Signal complexity was determined using the Lempel-Ziv (LZ) algorithm.
Fold increase in BF during LTH was 15.6 (10.3, 22.8) and in OxyHb 4.8 (3.5, 5.9) (median, range). All BF and OXY signals exhibited multiple oscillatory components with clear differences in signal power distribution across frequency bands at 33 and 43 °C. Significant reduction in the intrinsic variability and complexity of the microvascular signals during LTH was found, with mean LZ complexity of BF and OxyHb falling by 25% and 49%, respectively ( ).
These results provide corroboration that in human skin microvascular blood flow and oxygenation are influenced by multiple time-varying oscillators that adapt to local influences and become more predictable during increased haemodynamic flow.
Recent evidence strongly suggests that the inability of microvascular networks to adapt to an imposed stressor is symptomatic of disease risk which might be assessed via BF and OXY via the combination signal analysis techniques described here.
本研究旨在探讨血液流量（BF）和微循环氧合信号低频周期振荡的时变行为和算法复杂性。
使用激光多普勒流量仪和白光光谱仪，在局部皮肤温度保持在 33°C 时和 43°C 局部热充血（LTH）期间，从 15 名健康年轻男性中记录微血管 BF 和氧合（OXY：氧合血红蛋白、脱氧血红蛋白、总血红蛋白和 SO%）。在频率范围（0.0095-1.6 Hz）内评估 BF 和 OXY 信号的功率谱密度。使用 Lempel-Ziv（LZ）算法确定信号复杂度。
LTH 期间 BF 的倍数增加为 15.6（10.3，22.8），OxyHb 为 4.8（3.5，5.9）（中位数，范围）。所有 BF 和 OXY 信号均表现出多个振荡分量，在 33°C 和 43°C 时，信号功率在频带内的分布存在明显差异。在 LTH 期间，微血管信号的固有可变性和复杂性显著降低，BF 和 OxyHb 的平均 LZ 复杂度分别下降了 25%和 49%（）。
这些结果提供了佐证，表明在人体皮肤微血管中，血流和氧合受多个时变振荡器的影响，这些振荡器适应局部影响，并在血流增加时变得更可预测。
最近的证据强烈表明，微血管网络无法适应强制应激源的能力是疾病风险的症状，这可能通过这里描述的 BF 和 OXY 组合信号分析技术来评估。
