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目的探讨２１天头低位（ＨＤＴ）卧床对人体立位应激下心血管反应的影响，以及比较下体负压（ＬＢＮＰ）和头高位倾斜（ＨＵＴ）两种立位应激下心血管反应的差异。方法６名受试者在２１天ＨＤＴ前、后分别进行ＬＢＮＰ（－４．００ｋＰａ／３ｍｉｎ、－６．６７ｋＰａ／３ｍｉｎ及－９．３３ｋＰａ／３ｍｉｎ）和ＨＵＴ试验（３０°／３ｍｉｎ、４５°／３ｍｉｎ、６０°／３ｍｉｎ及７５°／３ｍｉｎ），以比较两种检测方法的血压（ＢＰ）和心率（ＨＲ）的变化情况。结果与ＬＢＮＰ（或ＨＵＴ）前相比：①ＬＢＮＰ（ＨＵＴ）时ＨＲ显著增加（Ｐ＜０．０１），ＳＢＰ显著降低（Ｐ＜０．０５）；卧床后相应的变化量增加。②ＬＢＮＰ时ＤＢＰ降低（卧床后达显著，Ｐ＜０．０５）；而ＨＵＴ时ＤＢＰ增加（卧床后达显著，Ｐ＜０．０５）。③ＬＢＮＰ时ＭＡＰ均显著降低（Ｐ＜０．０５）；而ＨＵＴ时在卧床前无变化（Ｐ＞０．０５），在卧床后显著增加（Ｐ＜０．０５）。结论ＬＢＮＰ和ＨＵＴ引起的ＣＶＳ反应并不相同。笔者认为，ＨＵＴ更能促进心血管系统对立位应激的调节作用。
Objective To investigate the effect of 21-day-old low bed rest on cardiovascular responses to ambulatory orthostatic stress in humans and to compare the differences of cardiovascular responses between two types of standing stress, hypobaric chamber pressure (LBNP) and head elevation tilt (HUT). Methods Six subjects underwent LBNP (-4.00kPa / 3min, -6.67kPa / 3min and -9.33kPa / 3min) and HUT test (30 ° / 3min, 45 ° / 3min, 60 ° / 3min and 75 ° / 3min) to compare the blood pressure (BP) and heart rate (HR) changes of the two methods. Results Compared with those before LBNP (or HUT), HR increased significantly (P <0.01), SBP decreased significantly (P <0.05) in LBNP (HUT), and increased correspondingly after bed rest. (2) DBP decreased (significant after bedridden, P <0.05) at LBNP; and increased at DBH (significant after bed rest, P <0.05). (3) MAP in LBNP was significantly decreased (P <0.05); HUT did not change before bedridden (P> 0.05), but significantly increased in bedridden (P <0.05). Conclusions The CVS responses induced by LBNP and HUT are not the same. The author believes that HUT can promote the regulation of the cardiovascular system on the standing stress.