Brauer P, Kochs E, Werner C, Bloom M, Policare R, Pentheny S, Yonas H, Kofke W A, Schulte am Esch J
Department of Anesthesiology, University Hospital Eppendorf, Hamburg, Germany.
J Neurosurg Anesthesiol. 1998 Apr;10(2):80-5. doi: 10.1097/00008506-199804000-00003.
Several studies suggest that relative changes in cerebral blood flow (CBF) may be assessed via transcranial Doppler sonography (TCD). The present study investigates the correlation between changes in TCD-mean flow velocity (Vm) and changes in CBF in patients with a variety of types of intracranial pathology undergoing cerebrovascular reactivity tests. After informed consent was obtained, 32 patients presenting with stenoses of brain-supplying arteries (n = 13), cerebral vascular malformations (n = 6), surgical decompression for subarachnoid hemorrhage (n = 2), brain edema after closed head injury (n = 8), or hepatic encephalopathy (n = 3) were studied. The patients were divided into two groups for different reactivity tests. Patients in group 1 (awake or sedated, n = 18) received a 1-g dose of acetazolamide intravenously. In group 2 (n = 14), mechanical ventilation was adjusted to produce a 20% decrease in arterial CO2 tension compared with baseline. Regional CBF was measured using xenon-enhanced computed tomography (Xe-CT). Xe-CT scans at the levels of the basal ganglia and the lateral ventricles were performed during a 4.5-min xenon wash-in period. Bilateral flow velocity was measured in the middle cerebral artery using a 2-MHz pulsed TCD system. Mean arterial blood pressure, heart rate, and end-tidal CO2 were continuously recorded during the procedure. After baseline measurements and either alteration of CO2 or application of acetazolamide, the cerebrovascular reactivity was assessed at 20 min by a second measurement of CBF, TCD, and all other physiologic variables. The correlation coefficient for relative changes of MCA territory CBF versus Vm and for the overall population was r = 0.82. In groups 1 and 2, the r values were 0.39 and 0.5, respectively. Correlation coefficients did not exceed r = 0.4 in any subgroup-classification based on diagnosis. The close correlation between changes in CBF and Vm (r = 0.82) in patients with heterogeneous intracranial pathology seems to show that TCD is a measure of CBF. However, in groups 1 and 2 and in subgroups formed of patients classified according to diagnoses, data dispersion suggests that the actual correlation is weaker. Relation of changes in Vm to those in CBF may depend on the underlying diagnosis. These data indicate that the correlation between Vm and CBF may vary with intracranial pathology.
多项研究表明，可通过经颅多普勒超声检查（TCD）评估脑血流量（CBF）的相对变化。本研究调查了接受脑血管反应性测试的各种类型颅内病变患者中，TCD平均流速（Vm）变化与CBF变化之间的相关性。在获得知情同意后，对32例患者进行了研究，这些患者分别患有脑供血动脉狭窄（n = 13）、脑血管畸形（n = 6）、蛛网膜下腔出血手术减压（n = 2）、闭合性颅脑损伤后脑水肿（n = 8）或肝性脑病（n = 3）。将患者分为两组进行不同的反应性测试。第1组患者（清醒或镇静，n = 18）静脉注射1 g剂量的乙酰唑胺。第2组患者（n = 14），将机械通气调整为使动脉血二氧化碳分压较基线降低20%。使用氙增强计算机断层扫描（Xe-CT）测量局部脑血流量。在4.5分钟的氙气注入期内，在基底节和侧脑室水平进行Xe-CT扫描。使用2 MHz脉冲TCD系统测量大脑中动脉的双侧流速。在操作过程中持续记录平均动脉血压、心率和呼气末二氧化碳。在进行基线测量以及改变二氧化碳或应用乙酰唑胺后，在20分钟时通过再次测量CBF、TCD和所有其他生理变量来评估脑血管反应性。大脑中动脉区域CBF相对变化与Vm相对变化以及总体人群的相关系数为r = 0.82。在第1组和第2组中，r值分别为0.39和0.5。在基于诊断的任何亚组分类中，相关系数均未超过r = 0.4。颅内病变类型各异的患者中，CBF变化与Vm变化之间的密切相关性（r = 0.82）似乎表明TCD是脑血流量的一种测量方法。然而，在第1组和第2组以及根据诊断分类的患者组成的亚组中，数据离散表明实际相关性较弱。Vm变化与CBF变化的关系可能取决于潜在诊断。这些数据表明，Vm与CBF之间的相关性可能因颅内病变而异。
