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头低位卧床休息时脑自动调节动力学的变化。

Changes in kinetics of cerebral auto-regulation with head-down bed rest.

作者信息

Pavy-Le Trao Anne, Costes-Salon Marie-Claude, Vasseur-Clausen Pascale, Bareille Marie-Pierre, Maillet Alain, Parant Marc

机构信息

Neurology Department, Rangueil Hospital, Toulouse, France.

出版信息

Clin Physiol Funct Imaging. 2002 Mar;22(2):108-14. doi: 10.1046/j.1365-2281.2002.00403.x.

Abstract

Thoraco-cephalic fluid shift induced by weightlessness may influence cerebral autoregulation. Our objective was to assess effects of simulated weightlessness by a 7-day head-down bed rest (HDBR) on the kinetics of cerebral blood flow (CBF) autoregulation in eight healthy women (27.9 +/- 0.9 years). This was studied by transcranial Doppler (TCD) of the middle cerebral artery (MCA) during the sudden decrease in blood pressure (BP) induced by quickly deflating thigh cuff aftera 4-min arterial occlusion before (D - 3), during (D2, D5) and after the HDBR (D + 1). BP (Finapres) and MCA maximal blood flow velocity were continuously recorded. Cerebrovascular resistance (CR) was expressed as the ratio of mean BP to mean MCA velocity. The CR slope was defined as changes in CR per second during the BP decrease. The magnitude of the relative decrease in mean BP and MCA velocity as well as the CR slope did not differ significantly before, during and after the HDBR, showing no major impairment of cerebral autoregulation during short-term HDBR. The time to maximum decrease in CR (T1 in s), corresponding to the maximum vasodilation was reduced on D2 (7-2 +/- 0.6) versus D - 3 (9.9 +/- 1-3), D5 (9-6 +/- 0.8) and R + 1 (11.7 +/- 11) probably as a result of the fluid shift. We also looked if the responses during the thigh cuff release differed in women according to their tolerance to the 10 min stand test performed after the HDBR: T1 was larger in the five women who presented orthostatic intolerance suggesting that some differences in cerebral autoregulatory responses may be related to orthostatic intolerance.

摘要

失重引起的胸-头体液转移可能会影响脑自动调节。我们的目的是评估8名健康女性(27.9±0.9岁)进行7天头低位卧床休息(HDBR)模拟失重对脑血流(CBF)自动调节动力学的影响。在HDBR前(D - 3)、期间(D2、D5)和之后(D + 1),通过在4分钟动脉闭塞后快速放气大腿袖带诱导血压(BP)突然下降期间,对大脑中动脉(MCA)进行经颅多普勒(TCD)研究。连续记录BP(Finapres)和MCA最大血流速度。脑血管阻力(CR)表示为平均BP与平均MCA速度的比值。CR斜率定义为BP下降期间每秒CR的变化。HDBR前、期间和之后,平均BP和MCA速度的相对下降幅度以及CR斜率没有显著差异,表明短期HDBR期间脑自动调节没有严重受损。对应最大血管舒张的CR最大下降时间(T1,单位为秒)在D2(7.2±0.6)比D - 3(9.9±1.3)、D5(9.6±0.8)和D + 1(11.7±1.1)缩短,这可能是体液转移的结果。我们还研究了HDBR后进行10分钟站立试验耐受性不同的女性在大腿袖带松开时的反应是否不同:在出现体位性不耐受的5名女性中,T1更大,这表明脑自动调节反应的一些差异可能与体位性不耐受有关。

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