Jan Yih-Kuen, Liao Fuyuan
University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:1753-6. doi: 10.1109/IEMBS.2011.6090501.
Local heating causes an increase in skin blood flow by activating sensory axon reflex and metabolic nitric oxide controls. It has been observed that the remote skin area without temperature changes also shows a slightly increase in blood flow. The responsible mechanism of this indirect vasodilation remains unclear. We hypothesized that the remote skin area will have enhanced synchronization of blood flow oscillations (BFO), thus inducing a vasodilatory response. We studied BFO in two sites separated 10 cm of the sacral skin in 12 healthy people. Ensemble empirical mode decomposition method was used to decompose blood flow signals into a set of intrinsic mode functions (IMFs), and an IMF was selected to quantify each of myogenic, neurogenic, and metabolic modes of BFO. Then the instantaneous phase of the mode was calculated using the Hilbert transform. From the time series of phase difference between a pair of characteristic modes, we detected the epochs of phase synchronization and estimated the level of statistical significance using surrogate time series. The results showed that phase synchronization between neurogenic BFO was significantly higher in the period of the maximal vasodilation. We also observed a weak synchronization between myogenic BFO of the two skin sites. Our results suggested that synchronization of BFO may be associated with the changes in skin blood flow at the non-heated site.
局部加热通过激活感觉轴突反射和代谢性一氧化氮调控机制，使皮肤血流量增加。据观察，未发生温度变化的远端皮肤区域血流量也略有增加。这种间接血管舒张的相关机制尚不清楚。我们推测，远端皮肤区域的血流振荡（BFO）同步性会增强，从而引发血管舒张反应。我们对12名健康受试者骶部皮肤相距10厘米的两个部位的BFO进行了研究。采用总体经验模态分解方法将血流信号分解为一组本征模态函数（IMF），并选取一个IMF对BFO的肌源性、神经源性和代谢性模式进行量化。然后利用希尔伯特变换计算该模式的瞬时相位。从一对特征模式之间的相位差时间序列中，我们检测到相位同步的时段，并使用替代时间序列估计统计显著性水平。结果显示，在最大血管舒张期，神经源性BFO之间的相位同步性显著更高。我们还观察到两个皮肤部位的肌源性BFO之间存在微弱同步。我们的结果表明，BFO的同步性可能与未加热部位皮肤血流量的变化有关。
