头低位暴露后直立位下体负压作用的耐力变化和心血管反应(英文)  

Changes of Tolerance and Cardiovascular Responses to Head-up Tilte Combined with LBNP Following Preceding Exposure to Head-down Tilt

作　　者：姚永杰[1] 孙喜庆[1] 杨长斌[1] 刘挺松[1] 吴燕红[1] 

机构地区：[1]第四军医大学航空航天医学系,陕西西安710032

出　　处：《航天医学与医学工程》2006年第3期157-162,共6页Space Medicine & Medical Engineering

摘　　要：目的观察头低位后直立位下体负压暴露的耐力和心血管反应。方法8名被试者在下体负压倾斜床上进行“直立位-倒立位30s-直立位联合下体负压(-60mmHg)致晕厥前症状”的模拟推拉效应试验及单纯直立位+下体负压(-60mmHg)致晕厥前症状的对照试验,用阻抗法测量了试验过程中心血管功能指标的变化。结果在模拟推拉效应试验中,8名被试者出现晕厥前症状的平均耐受时间为4.5±2.4min,显著低于对照试验时的8.4±2.1min(P<0.01)。在倒立位,被试者HR较直立位基础值降低,SV和CO较直立位基础值升高,均有显著性意义。和基础值相比,直立位下体负压时HR增加的百分比显著低于对照试验(P<0.05),而直立位下体负压时SV和CO降低的百分比均显著高于对照试验时SV和CO降低的百分比(P<0.05)。在直立位下体负压暴露时,对照试验的PP和基础值比较显著降低(P<0.05),TPR比基础值显著增加(P<0.05)。结论倒立位后,再进行直立位下体负压作用,出现晕厥前症状的平均耐受时间缩短,心血管反应降低。Objective To observe pre-syncopal limited tolerance and cardiovascular responses to headup tilt combined with lower body negative pressure （HUT/LBNP） following exposure to head-down tilt （HDT,-1Gz）. Method Exposures to HUT/LBNP （ -60 mmHg） in control session （without preceding 30 s - 1 Gz treatment） and in simulated push-pull effect （PPE） session （with preceding 30 s - 1 Gz treatment） were performed in 8 healthy adults. The changes of hemodynamic parameters were monitored by electrical impedance instrument during the experiments. Result The mean endurance time in presyncopal symptom limited HUT/LBNP in control session and in simulated PPE session were 8.4 ± 2.1 rain and 4.5 ± 2.4 rain, respectively, the two means were significantly different （P 〈 0.01）. In simulated PPE session, as compared with baseline, heart rate （HR） during HDT was significantly lowered （P 〈0.01）, while stroke volume （SV） and cardiac output （CO） were increased significantly （P 〈0.01）. During HUT/LBNP, the increased percentage （ relative to baseline） of HR in PPE session was lower than these in control session （P 〈0.05） ; the decreased percentages of SV and CO during HUT/LBNP in PPE session were both higher than those in control session （P 〈0.05）. During HUT/LBNP, arterial pulse pressure （PP） of control session was significantly decreased than the value of baseline value （P 〈0.05）; Total peripheral resistance （TPR） of PPE session was significantly increased than baseline value （P 〈0. 05）. Conclusion Tolerance time before the appearance of presyncopal symptoms during HUT/LBNP decreases and cardiovascular responses to HUT/LBNP are impaired, preceding exposure to HDT.

关 键 词：下体负压 倾斜床 推拉动作 推拉效应 加速度致意识丧失 心血管系统 

分 类 号：R852.21[医药卫生—航空、航天与航海医学]