模拟失重对心脏的影响及四肢加压套带和下体负压的拮抗作用

Cardiac changes during simulated weightlessness with and without cuffs and low body negative pressure

目的 研究模拟失重对心脏形态的影响及其用四肢加压套带和下体负压的拮抗作用 .方法 自愿接受试验的健康男性青年 18名 ,年龄 19～ 2 5 (平均 2 2 .6 )岁 ,随机分为对照组 ,套带组和下体负压组 ,进行 2 1d6°头低位卧床试验 .对照组卧床中不用任何对抗措施 ;套带组卧床期间每日 0 8∶ 30～2 0∶ 30 ,四肢戴加压套带 ,压力维持在 5 .3k Pa;下体负压组卧床期间第 1wk和最后 1wk每日 15 :0 0使用 1h下体负压裤 ,压力维持在 - 4k Pa.所有组均分别于卧床前 1d和卧床结束后 1d摄取 X线胸片各 1张 ,测量胸廊横径、心脏横径、长径和宽径 ,并计算反映心脏形态大小的心胸比和心脏面积 .结果 对照组心脏横径减少 0 .5 4cm,心胸比减少 0 .0 2 4,心脏面积减少 9cm2 ,前后比较均有明显差异 (P<0 .0 5 ) ;套带组分别减少 0 .5 0 cm,0 .0 2 1和 1.9cm2 ,前后比较无显著性差异 (P>0 .0 5 ) ;下体负压组各指标变化不明显 (P>0 .0 5 ) .结论 头低位卧床模拟失重对心脏形态有明显的影响 。

AIM To investigated the effects of simulated weightlessness on cardiac morphology and counteracting effects of cuffs and low body negative pressure (LBNP) on them. METHODS The 21d -6° head down bed rest was used to simulate weightlessness. Eighteen young healthy volunteers were divided into 3 groups randomizedly: cuffs group, LBNP group and control group. In cuffs group, cuffs on the upper part of thighs and arms were inflated from 8:30 am to 20:30 pm during bed rest with pressure 5.3 kPa. In LBNP group, low body pressure was maintained at -4 kPa for one hour from 15:00 pm to 16:00 pm during the first and last week of bed rest. X ray examination was used to study the cardiac morphology changes during simulated weightlessness. All groups were taken X ray examination one day before and after bed rest and the alongside of thoracic cage and cardiac transverse diameter were measured. Also, the cardiac thoracic ratio and area of heart were calculated. RESULTS The alongside of thoracic cage, cardiac thoracic ratio and area of heart were significantly decreased after bed rest in control group. However, there were no significant differences in cuffs and LBNP groups after bed rest. CONCLUSION It is suggested that simulated weightlessness, conducted by head down bed rest has great influences on cardiac morphology and cuffs and LBNP can counteract the effects of simulated weightlessness.