急性轻中度缺氧条件下心率及收缩压变异性谱变化

目的：应用心率及收缩压变异性（HRV、SBPV）谱分析方法评价急性轻中度缺氧条件下心血管自主神经调节的变化。方法：10名健康男性青年分别吸入氧13．7％（相当于海拔3500m)和11％（相当于海拔5000m）两种氮－氧混合气各20min，将对照和缺氧条件下的HRV和SBPV谱变化进行对比分析。结果：在两种缺氧条件下，受试者均出现血压下降、心率增快反应，HRV谱总功率（TP）和高频成分（HF）功率均显著减小，低频成分（LF）功率与LF／HF功率比值无显著变化，SBPV谱LF功率显著增大，3名缺氧耐力不良受试者尤为明显。不同水平缺氧之间的数值比较差异均无显著性意义。结论：急性轻中度缺氧条件下，人副交感神经抑制，交感神经兴奋，联合应用HRV与SBPV谱分析方法可对心血管自主神经调节活动进行评定；但HRV的LF成分变化机理较为复杂。

Changes in spectra of heart rate and systolic blood pressure variabilities during acute mild and moderate hypoxia in man

Objective To evaluate the changes in cardiovascul ar autonomic regulation by spectral analysis of heart rate and systolic blood pr essure variabilities (HRV and SBPV) during acute mild and moderate hypoxia in ma n. Methods Ten healthy young men served as subjects. They unde rwent mild hypoxia exposure (breathing 13.7% O 2 gas mixture, corresponding to 3 500 m altitude) and moderate hypoxia exposure (breathing 11% O 2 gas mixture , corresponding to 5 000 m altitude) for 20 min separately. ECG and beat by beat blood pressure signals were recorded and analysed. Results D uring both levels of hypoxia, blood pressure decreased and heart rate increased significantly. Total power (TP) and high-frequency component (HF) of HRV spectr um decreased significantly, while low-frequency component (LF) and LF/HF power ratio remained unchanged, LF power of SBPV spectrum increased significantly espe cially in 3 men who couldn't tolerate 11% hypoxia for 20 min. The differences be tween data of the two levels of hypoxia were non-significant. Conclusi on The parasympathetic nerve activity is inhibited and sympathetic nerv e is activated during these two levels of hypoxia. HRV together with SBPV spectr al analysis can be used for evaluation of cardiovascular autonomic regulation. B ut the mechanism of change in LF component of HRV spectrum is rather complicated .