Effects of 18 days of bed rest on leg and arm venous properties.
Effects of 18 days of bed rest on leg and arm venous properties.
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卧床休息 18 天对腿部和手臂静脉特性的影响。
DOI：
10.1152/japplphysiol.00835.2003
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Levine,BD
中科院分区：
文献类型：
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作者：
Bleeker,MWP;DeGroot,PCE;Pawelczyk,JA;Hopman,MTE;Levine,BD
静脉功能可能因卧床休息而改变。然而，卧床休息后观察到的直立性不耐受与静脉顺应性改变的关系尚不确定。本研究的目的是评估18天卧床休息对腿部和手臂静脉特性的影响（分别是重力梯度和使用模式的大变化和小变化）。我们假设这些静脉变化的大小与直立性不耐受有关。11名健康受试者（10名男性，1名女性）参加了本研究。6°上下倾斜卧床18天前（前）、后（后），采用应变计静脉闭塞容积描记术评估肢体静脉血管特征。卧床休息后下肢静脉顺应性显著降低（术前：0.048±0.007 ml·100 ml-1·mmHg-1，术后：0.033±0.007 ml·100 ml-1·mmHg-1， P< 0.01），而上肢顺应性无变化。卧床休息后腿部静脉血流阻力显著升高（术前：1.73±1.08 mmHg·ml-1·100 ml·min，术后：3.10±1.00 mmHg·ml-1·100 ml·min；P< 0.05）。所有受试者在卧床休息后（休息前：932 mmHg·min，休息后：747 mmHg·min），最大下体负压耐受性（以累积应激指数（压力·时间）表示）均下降。直立耐受性的降低与腿部静脉顺应性的变化无关。综上所述，本研究表明卧床休息后腿部静脉顺应性降低，腿部静脉流出阻力增强。然而，这些变化与直立耐受性的测量无关；因此，静脉顺应性的改变在头向下倾斜床休息18天后的直立性不耐受中不起主要作用。
Venous function may be altered by bed rest deconditioning. Yet the contribution of altered venous compliance to the orthostatic intolerance observed after bed rest is uncertain. The purpose of this study was to assess the effect of 18 days of bed rest on leg and arm (respectively large and small change in gravitational gradients and use patterns) venous properties. We hypothesized that the magnitude of these venous changes would be related to orthostatic intolerance. Eleven healthy subjects (10 men, 1 woman) participated in the study. Before (pre) and after (post) 18 days of 6° head-down tilt bed rest, strain gauge venous occlusion plethysmography was used to assess limb venous vascular characteristics. Leg venous compliance was significantly decreased after bed rest (pre: 0.048 ± 0.007 ml·100 ml-1·mmHg-1, post: 0.033 ± 0.007 ml·100 ml-1·mmHg-1;P< 0.01), whereas arm compliance did not change. Leg venous flow resistance increased significantly after bed rest (pre: 1.73 ± 1.08 mmHg·ml-1·100 ml·min, post: 3.10 ± 1.00 mmHg·ml-1·100 ml·min;P< 0.05). Maximal lower body negative pressure tolerance, which was expressed as cumulative stress index (pressure·time), decreased in all subjects after bed rest (pre: 932 mmHg·min, post: 747 mmHg·min). The decrease in orthostatic tolerance was not related to changes in leg venous compliance. In conclusion, this study demonstrates that after bed rest, leg venous compliance is reduced and leg venous outflow resistance is enhanced. However, these changes are not related to measures of orthostatic tolerance; therefore, alterations in venous compliance do not to play a major role in orthostatic intolerance after 18 days of head-down tilt bed rest.