Gambhir S, Inao S, Tadokoro M, Nishino M, Ito K, Ishigaki T, Kuchiwaki H, Yoshida J
Department of Radiology, Nagoya University School of Medicine, Japan.
Neurol Res. 1997 Apr;19(2):139-44. doi: 10.1080/01616412.1997.11740787.
Carbon dioxide (CO2) and acetazolamide are increasingly being used as vasodilators to detect cerebrovascular reserve capacity in patients of chronic cerebrovascular disease. The functional cerebrovascular reserve or ability of cerebral vessels to lower their resistance in response to decrease in cerebral perfusion pressure is expressed as change in cerebral blood flow from baseline under a vasodilatory stimuli. Theoretically a vasodilator causing maximum vasodilation, and thereby expressing complete reserve capacity would be more suitable for such a purpose. We quantitatively compared the vasodilating effect of 5% CO2 inhalation and 1 g of intravenous acetazolamide by positron emission tomography. Cerebrovascular reserve was quantified in six patients with chronic cerebrovascular disease in the same sitting, using oxygen-15 labeled water (H2(15)O) positron emission tomography at rest, during 5% CO2 inhalation and after 1 g intravenous acetazolamide. A significant linear correlation in both nonlesion hemisphere (r = 0.701, p < 0.001) and in lesion hemisphere (r = 0.626, p < 0.005) was found between CO2 and acetazolamide for cerebrovascular reserve capacity. This correlation improved by considering cerebrovascular reserve per unit change in arterial carbon dioxide (r = 0.744, p < 0.001 in nonlesion hemisphere and r = 0.721, p < 0.001 in lesion hemisphere). The quantitative value of global reserve capacity was different by CO2 stimuli (5.2%) and acetazolamide (49.7%). Though a similar vasodilatory response is elicited by both vasodilators, acetazolamide seems to be more potent and therefore should be preferred to detect patients with exhausted cerebrovascular reserve capacity.
二氧化碳（CO₂）和乙酰唑胺越来越多地被用作血管扩张剂，以检测慢性脑血管疾病患者的脑血管储备能力。功能性脑血管储备或脑血管在脑灌注压降低时降低其阻力的能力，表现为在血管扩张刺激下脑血流量相对于基线的变化。从理论上讲，一种能引起最大血管扩张从而表达完全储备能力的血管扩张剂更适合用于此目的。我们通过正电子发射断层扫描定量比较了吸入5% CO₂和静脉注射1 g乙酰唑胺的血管扩张效果。在同一时间段内，对6例慢性脑血管疾病患者进行了脑血管储备的定量分析，使用氧-15标记水（H₂¹⁵O）正电子发射断层扫描，分别在静息状态、吸入5% CO₂期间以及静脉注射1 g乙酰唑胺后进行检测。在非病变半球（r = 0.701，p < 0.001）和病变半球（r = 0.626，p < 0.005）中，均发现CO₂和乙酰唑胺在脑血管储备能力方面存在显著的线性相关性。通过考虑每单位动脉二氧化碳变化的脑血管储备，这种相关性得到了改善（非病变半球r = 0.744，p < 0.001；病变半球r = 0.721，p < 0.001）。全局储备能力的定量值在CO₂刺激下为5.2%，在乙酰唑胺刺激下为49.7%。尽管两种血管扩张剂引起的血管扩张反应相似，但乙酰唑胺似乎更有效，因此在检测脑血管储备能力耗尽的患者时应优先选用。
