MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis
MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis
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DOI：
10.1161/01.str.31.7.1672
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发表时间：
2000-07-01
期刊：
影响因子：
8.3
通讯作者：
Bondar, RL
中科院分区：
文献类型：
--
作者：
Serrador, JM;Picot, PA;Bondar, RL
背景和目的-大脑中动脉（MCA）血流速度（CFV）和脑血流（CBF）之间的关系是不确定的，因为血管直径对生理刺激的反应是未知的。本研究的目的是直接检查的效果，模拟直立应力（下体负压[LBNP]），以及增加或减少潮气末二氧化碳分压（PETCO 2）对MCA直径和CFV.Methods-Twelve的主题参加了二氧化碳操作协议和/或LBNP协议。在CO2操作方案中，受试者呼吸室内空气（正常碳酸血症）或吸入6%的CO（高碳酸血症），或过度通气至约25 mmHg PETCO 2（低碳酸血症）。在LBNP方案中，受试者经历了10分钟的-20和-40 mm Hg下体抽吸。结果：与正常碳酸血症组相比，高碳酸血症组PETCO 2增加（从36+/-3到40+/-4 mm Hg，P
Background and Purpose-The relationship between middle cerebral artery (MCA) flow velocity (CFV) and cerebral blood now (CBF) is uncertain because of unknown vessel diameter response to physiological stimuli. The purpose of this study was to directly examine the effect of a simulated orthostatic stress (lower body negative pressure [LBNP]) as well as increased or decreased end-tidal carbon dioxide partial pressure (PETCO2) on MCA diameter and CFV.Methods-Twelve subjects participated in a CO2 manipulation protocol and/or an LBNP protocol. In the CO2 manipulation protocol, subjects breathed room air (normocapnia) or 6% inspired CO, (hypercapnia), or they hyperventilated to approximate to 25 mmHg PETCO2 (hypocapnia). In the LBNP protocol, subjects experienced 10 minutes each of -20 and -40 mm Hg lower body suction. CFV and diameter of the MCA were measured by transcranial Doppler and MRI, respectively, during the experimental protocols.Results-Compared with normocapnia, hypercapnia produced increases in both PETCO2 (from 36+/-3 to 40+/-4 mm Hg, P