Variability of cerebral blood volume and oxygen extraction: stages of cerebral haemodynamic impairment revisited
Variability of cerebral blood volume and oxygen extraction: stages of cerebral haemodynamic impairment revisited
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DOI：
10.1093/brain/awf047
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发表时间：
2002-03-01
期刊：
影响因子：
14.5
通讯作者：
Powers, WJ
中科院分区：
文献类型：
--
作者：
Derdeyn, CP;Videen, TO;Powers, WJ
闭塞性脑血管疾病引起的血流动力学损害的存在或程度通常通过脑血流量（CBF）、脑血容量（CBV）、氧提取分数（OEF）和脑氧代谢率（cmor2）的测量来推断。然而，在亚急性或慢性疾病患者中，这些变量（特别是CBV）与区域脑血流动力学的关系尚未明确确立。在本研究中，我们研究了单侧颈动脉闭塞患者CBV与OEF、CBF和cmor2的关系，以及与随后卒中风险的关系，以便更好地确定相关的血流动力学和代谢变化。我们回顾了81例有症状的颈动脉闭塞患者的资料，这些患者参加了一项血流动力学因素和卒中风险的前瞻性研究。入行时用PET测定CBV、CBF、OEF和cmo 2。在与正常对照比较的基础上，根据半球比和OEF和CBV的同侧绝对值将患者分为两组。比较两组患者血流动力学和代谢值、危险因素及卒中风险。根据半球比例，45例患者的同侧OEF增加；这45例患者中有19例CBV升高。这19例患者与其余26例OEF升高、CBV正常或降低的患者在CBF、cmor2或临床危险因素方面均无差异。随访期间发生13例同侧卒中，其中10例发生在OEF和CBV升高的19例患者中（log rank P < 0.0001）。有完整定量PET数据的68例患者中有32例OEF的绝对同侧值增加。32例患者中有20例CBV升高。这20例患者与其余12例OEF升高而CBV正常的患者在CBF、cmor2或临床危险因素方面均无差异。在68例患者中发生的9例同侧卒中中，有7例发生在OEF和CBV升高的20例患者中（log rank P = 0.003）。OEF和CBV增加的患者发生缺血性卒中的风险更高，这表明他们的血流动力学损害程度比OEF增加和CBV正常的患者更严重。在慢性颈动脉闭塞和OEF升高的患者中，CBV升高可能表明由于自身调节血管舒张衰竭而引起的血管舒张明显。对于OEF升高的患者测量正常CBV的生理解释不太确定，可能反映了保留的自我调节能力。
The presence or degree of haemodynamic impairment due to occlusive cerebrovascular disease is often inferred from measurements of cerebral blood flow (CBF), cerebral blood volume (CBV), oxygen extraction fraction (OEF) and the cerebral rate for oxygen metabolism (CMRO2). However, the relationship of these variables, in particular CBV, to regional cerebral haemodynamics is not clearly established in humans with subacute or chronic disease. In the present study, we investigated the relationship of CBV to OEF, CBF and CMRO2, and to subsequent stroke risk in patients with unilateral carotid artery occlusion, in order to define better the associated haemodynamic and metabolic changes. We reviewed data from 81 patients with symptomatic carotid occlusion enrolled in a prospective study of haemodynamic factors and stroke risk. Measurements of CBV, CBF, OEF and CMRO2 were made on entry using PET. Patients were divided into groups by hemispheric ratios and absolute ipsilateral values of OEF and CBV, based on comparison with normal controls. Haemodynamic and metabolic values, risk factors and stroke risk were compared between groups. Based on hemispheric ratios, 45 patients had increased ipsilateral OEF; CBV was increased in 19 of these 45 patients. No differences in CBF, CMRO2 or clinical risk factors were found between these 19 patients and the remaining 26 patients with increased OEF and normal or reduced CBV. Thirteen ipsilateral strokes occurred during follow-up, and 10 of the 13 occurred in the 19 patients with increased OEF and CBV (log rank P < 0.0001). Thirty-two of the 68 patients with complete quantitative PET data had increased OEF by absolute ipsilateral values. CBV was increased in 20 of the 32 patients. No differences in CBF, CMRO2 or clinical risk factors were found between these 20 patients and the remaining 12 patients with increased OEF and normal CBV. Seven of the nine ipsilateral strokes that occurred in the 68 patients occurred in those 20 patients with increased OEF and increased CBV (log rank P = 0.003). The higher risk of ischaemic stroke in patients with increased OEF and CBV suggests that their degree of haemodynamic compromise is more severe than those with increased OEF and normal CBV. In patients with chronic carotid occlusion and increased OEF, increased CBV may indicate pronounced vasodilation due to exhausted autoregulatory vasodilation. The physiological explanation for the measurement of normal CBV in patients with increased OEF is less certain and may reflect preserved autoregulatory capacity.