21d头低位卧床期间TCD检测套带对大脑中动脉血流变化的影响

Treatise Transcranial doppler assessment the change of blood flow of middle cerebral artery during 21d head-down tilt bed-rest with and without cuffs

目的观察21d头低位卧床期间套带对大脑中动脉血流变化的影响。方法12名健康男性志愿者随机分为对照组和套带组,每组6人,进行21d(-6°)卧床试验。套带组卧床第1～21天,每天8:30～20:30四肢加压套带,压力维持在5.3kPa;对照组不做任何对抗措施。卧床前、卧床第10天及卧床结束时进行了3次立位耐力试验。卧床前、卧床第1、3、10、21天用经颅超声多普勒(TCD)测量大脑中动脉血流动力学指标。结果对照组21d卧床期间大脑中动脉血流速度下降,血流量减少,其中卧床第3天和第21天较卧床前血流速(Vs,Vm)明显降低,血流量减少(P<0.05或P<0.01)。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=0.05)。卧床第10天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21d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。

Objective To investigate the changes of blood flow of human Middle Cerebral Artery（MCA） during 21 d simulated weightlessness with and without euffs.Methods 12 healthy males were exposed to 21 d （-6°） head-down tilt bed rest （HDT） to simulate weightlessness.They were divided into cuffs group and control group, with 6 subjects in each group. Inflat- ed cuffs on the upper part of thighs and arms were performed 12 h/d in cuffs group during HDT,the pressure were 5.3 kPa. there was no countermeasures in control group.HUT＋75°20 min orthostatie tolerance test were performed at day 10 and 21 of HDT. The Vs （systolic peak flow velocity）,Vm （mean peak flow velocity）,Vd （diastolic peak flow velocity）,RI （resistance index）, PI （pulsatility index） of right MCA were measured by transcranial Doppler before HDT and at dayl,3,10,21 of HDY. Results compared with those of pre-HDT, Vs and Vm of MCA In control group at day 3 and 21 of HDT reduced significantly （P〈0. 05,P〈0.01）. there was no significant changes in Vd,RI and PI .PI In cuffs group at the first day of HDT were significant lowered than those of pre-HDT （P=-0.05）. The results of orthostatic tolerance tests on day 10 of HDT and at the end of HDT showed there were 6 in the control group and 2 in the cuffs group failed to pass,and 4 in the cuffs group passed. Conclusion During the 21 d HDT bed-rest,the blood flow velocity of MCA could be reduced effectively by the use of cuffs. It can obviously improve the cerebral ischemia and poor orthostatic tolerance.