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目的观察２４ ｈ 头低位卧床对心血管系统功能和头高位倾斜心血管反应变化的影响。方法健康男性学员６ 名，年龄２２ ～２３ 岁，进行了２４ ｈ 头低位卧床实验，卧床期间用阻抗法测量了心脏泵血功能指标，并观察了卧床前后头高位倾斜时的心血管反应和卧床期间尿量的变化。结果在卧床期间受试者心率较卧床前（ 立位） 显著减慢，第６ 、１２ 、１８ ｈ 的心率较卧床开始时（０ ｈ） 显著降低。ＳＶ 和ＳＩ在卧床０ 、６ 、１２ 和２４ ｈ 较卧床前显著增加。ＣＯ 和ＣＩ 在第１８ ｈ 较０ ｈ 显著性降低。ＴＰＲ在第１８ ｈ 较０ ｈ 显著性增高。卧床前后ＨＵＴ 时，ＨＲ、ＭＢＰ、ＴＰＲ 显著增加，ＳＶ、ＳＩ、ＣＯ、ＣＩ显著下降，ＳＢＰ 变化不显著；卧床后ＨＵＴ 时，舒张压（ＤＢＰ） 显著增加，脉压差（ＰＰ） 显著下降，而卧床前ＨＵＴ 时，ＤＢＰ 和ＰＰ 变化不显著。卧床０ ～４ ｈ 的平均每小时尿量显著高于４ ～１２ ｈ 和１２ ～２４ 的平均小时尿量（ Ｐ＜ ０ ．０１） 。结论２４ 头低位卧床对心血管系统功能和头高位倾斜时的心血管反应有显著影响。
Objective To observe the effects of 24-hour head-down bed rest on changes of cardiovascular system function and head-tilt angiocardial response. Methods Six male healthy subjects aged from 22 to 23 years were enrolled in this study. The 24-hour low bed rest test was performed. During the ambulatory period, the cardiac pump function indexes were measured by impedance method. The cardiovascular responses and bed rest Period urine volume changes. Results During the ambulatory period, the heart rate of the subjects was significantly lower than that of the bed rest (standing position). The heart rate at 6, 12 and 18 h was significantly lower than that at the beginning of bed rest (0 h). SV and SI increased significantly at bedridden 0, 6, 12 and 24 h before bed rest. CO and CI significantly decreased at 0 h after 18 h. TPR significantly increased at 0 h compared with that at 18 h. The HR, MBP, TPR, SV, SI, CO and CI were significantly decreased and the SBP did not change significantly in HUT before and after bed rest; DBP increased significantly and pulse pressure difference (PP) While bedtime HUT, DBP and PP did not change significantly. The mean hourly urine output of bed rest from 0 to 4 hours was significantly higher than that from 4 to 12 hours and from 12 to 24 hours (P <0.01). CONCLUSIONS: 24 low bed rests significantly affect cardiovascular function and cardiovascular response at head tilt.