利用非线性方法研究头低位卧床对心血管调控机制的影响(英文)

目的本研究旨在用非线性分析方法,探讨-6°头低位卧床试验对心血管调控机制的影响,并将对照组和中药组进行比较。方法 14名男性健康志愿者随机分入对照组和中药组,进行60d的头低位卧床试验。在试验前、中、后,运用非线性分析技术对心率变异、血压变异进行测试。结果志愿者心率水平在卧床开始后的前21d保持稳定,但从卧床试验的第41天起显著升高,且在卧床结束后亦未恢复至正常;趋向波动指数(DFAα1)于卧床试验开始后的第2天出现明显升高,且维持升高状态至试验结束后的第12天;混沌指数(chaos)在卧床过程中明显下降。卧床试验过程中组间对比发现:对照组心率变异的1/f以及血压变异的SDNN、LF/HF、DFAα1和1/f明显高于中药组,并且心率变异的DFAα2和血压变异的HF明显降低。结论在卧床试验后期机体出现迷走神经张力下降,迷走交感平衡升高;而中药可以减轻模拟失重对心血管系统的影响。

Cardiovascular Control Mechanism during Head-down Bed Rest Using Nonlinear Techniques

Objective To investigate the influence of -6°head-down bed rest(HDBR) on the cardiovascular control mechanism and effects of Chinese herbal medicine (CHM) as a countermeasure. Methods Fourteen Chinese healthy men were randomly allocated to a control group and a CHM group. Heart rate and blood pressure variability ( HRV & BPV) were assessed before, during and after 60 d HDBR with a focus on nonlinear techniques to quantify scaling behaviour, chaotic behaviour and complexity. Results There was no change in heart rate till the 21st day of HDBR, but increased significantly from the 41st day,without any recovery afterwards. DFA α1 was significantly higher on the 2nd day of HDBR compared with baseline and remained so high until even 12 d after HDBR. The chaos level was drastically lower during HDBR compared with the peri od before HDBR. Over all time sessions, heart rate, HRV 1/f slope and the BPV parameters SDNN, LF/HF,DFA α1 and 1/f were significantly higher in the control group compared with CHM group although HRV DFA α2 and BPV HF showed significantly lower values. Conclusion It confirmed the reduced vagal modulation and higher sympathovagal balance at the end of HDBR. Moreover, a change in nonlinear heart rate and blood pressure dynamics during HDBR was still present after 1 week of recovery. It demonstrates that CHM has restricted some influences of HDBR on the cardiovascular regulation, only partially functions as a countermeasure.