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目的 探讨头低位卧床模拟失重过程中心脏 X线形态变化及四肢加压套带、下体负压的作用。 方法 18名健康男性青年 ,自愿接受试验 ,随机分为对照组、套带组和下体负压组 ,进行- 6°头低位卧床 2 1d试验。对照组卧床中不用任何对抗措施 ;套带组卧床期间每天 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 1周和最后 1周每天下午使用 1h下体负压裤 ,压力维持在 - 4k Pa。分别于卧床前 1d和卧床后 1d摄取 X线胸片 1张 ,按有关标准测量胸廊横径、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 对照组卧床后较卧床前心脏横径减小 0 .5 4cm,心胸比减小 0 .0 2 4,心脏面积减小 9cm2 ,差异有显著性意义。套带组和下体负压组心脏面积前后比较差异无显著性意义。 结论 头低位卧床 2 1d模拟失重过程可使心脏体积变小 ,这可能是心脏功能降低的结果 ,与有关实验结果相符 ;使用四肢加压套带和下体负压等对抗措施可以防止心脏形态改变 ,而下体负压作用效果及可操作性均优于四肢加压套带。
Objective To investigate the changes of cardiac X-ray and the effects of pressure banding and lower body pressure on the extremities during the head-lying ambulatory simulated weightlessness. Methods Eighteen healthy male adolescents were randomly divided into control group, cuffed group and lower body negative pressure group. Control group bed without any countermeasures; banding group bed day 0 8: 30 ~ 2 0: 30, wearing a pressure bandage on both limbs, the pressure maintained at 5.3kPa; lower body negative pressure group during the first week of bed rest and 1h lower body pressure pants are used every afternoon for the last week, the pressure is maintained at -4kPa. 1 chest X-ray and 1 chest X-ray respectively were taken before bedtime and 1 chest X-ray respectively. The chest diameter, heart diameter, long diameter and width were measured according to relevant standards, and the ratio of heart-chest size and heart area were calculated. Results Compared with the control group, the horizontal diameter of the bed before bedridden decreased by 0.54 cm, the heart-chest ratio decreased by 0.024, and the heart area decreased by 9 cm 2. The difference was statistically significant. There was no significant difference in the heart area between the cuff and lower body negative pressure group before and after treatment. CONCLUSIONS: The head-to-floor ambulation of the simulated weightlessness during 21 days of simulated bed-ridding may reduce the volume of the heart, which may be the result of reduced cardiac function, which agrees with the experimental results. Counter measures such as compression bandage on the extremities and negative pressure on the lower body prevent cardiac morphological changes, The effect of lower body negative pressure and maneuverability are better than the pressure on the limbs.