头低位卧床期间四肢加压套带预防大脑中动脉血流下降

Preventive effect of extremilies' cuffs on blood flow of middle cerebral artery during head-down tilt bed-rest

目的 观察头低位卧床 2 1d期间套带对大脑中动脉血流变化的影响 .方法 健康男性志愿者 12名随机分为对照组和套带组 ,每组 6人 ,进行 - 6°卧床试验 2 1d.套带组卧床每日 0 8:30～ 2 0 :30四肢加压套带 ,压力维持在 5 .3k Pa,对照组不做任何对抗措施 .卧床前、卧床 10 d及卧床结束时进行 3次立位耐力试验 .卧床前、卧床 1,3,10和 2 1d用经颅超声多普勒 (TCD)测量大脑中动脉血流动力学指标 .结果 对照组 2 1d卧床期间大脑中动脉血流速度下降 ,血流量减少 ,其中卧床 3 d和 2 1d较卧床前血流速 (vs,vm)明显降低 ,血流量减少 (P<0 .0 5或 P<0 .0 1) .套带组卧床期间及卧床结束时血流速度及血流量较卧床前无显著降低或减少 (P>0 .0 5 ) .卧床 10 d和卧床结束时立位耐力试验对照组 6人均未通过立位耐力试验 .套带组 4人顺利通过立位耐力试验 ,2人未通过立位耐力试验 .结论 头低位卧床期间使用套带能有效减缓大脑中动脉血流速度下降 ,对改善失重引起的脑缺血和立位耐力不良有明显的作用 .

AIM To investigate the changes of blood flow of human middle cerebral artery (MCA) during 21 d simulated weightlessness with cuffs. METHODS 12 healthy males were exposed to 21 d, -6° head down tilt bed rest (HDT) to simulate weightlessness. They were divided into cuff group and control group (6 in each group). Inflated cuffs on the upper part of thighs and arms were performed 12 h·d -1 in cuffs group during HDT, the pressure were 5.3 kPa. Control group had no countermeasures. HDT+75° 20 min orthostatic tolerance test on 10 and 21 days of HDT. The V s (systolic peak flow velocity), V m (mean peak flow velocity), V d (diastolic peak flow velocity), RI (resistance index), PI (pulsatility index) of right MCA were measured by transcranial Doppler before HDT and on 1, 3, 10, 21 days of HDY. RESULTS In control group, v s and v m of MCA on 3 and 21 days of HDT reduced significantly than those of pre HDT ( P <0.05, P <0.01). V d, RI and PI had no significant changes. In cuff group, only PI on the firstday of HDT were significant lowered than those of pre HDT ( P =0.05). The results of orthostatic tolerance tests on 10 days of HDT and at the end of HDT were that 6 in the control group and 2 in the cuff group failed to pass, but 4 in the cuff group passed. CONCLUSION During the 21 d HDT bed rest, the use of cuffs can effectively reduce the blood flow velocity of MCA. It can obviously improve the cerebral ischemia and poor orthostatic tolerance.