Markus H S, Vallance P, Brown M M
Division of Clinical Neuroscience, St George's Hospital Medical School, London, UK.
Stroke. 1994 Sep;25(9):1760-4. doi: 10.1161/01.str.25.9.1760.
Prostaglandins are believed to play an important role in maintenance of cerebral blood flow and possibly in the vasodilatory response to carbon dioxide. Therefore, the nonsteroidal anti-inflammatory drugs and aspirin, which inhibit cyclooxygenase, might be expected to reduce cerebral blood flow and the response to hypercapnia. This could induce cerebral ischemia in patients with a hemodynamically critical circulation. It would also interfere with the measurement of cerebrovascular reserve using carbon dioxide.
The effect of a single dose of indomethacin and of two other cyclooxygenase inhibitors (aspirin and sulindac) on the cerebral circulation was measured using transcranial Doppler ultrasonography of the middle cerebral artery. Seven normal adults were studied in each drug group. Resting blood flow velocity and the responses to hypercapnia and to hyperventilation were measured.
Indomethacin resulted in a fall in basal middle cerebral artery flow velocity from a mean of 48.9 cm/s to 34.0 cm/s (P < .002). It also reduced the vasoconstrictor response to hypocapnia (induced by hyperventilation) from 37.5% to 20.7% (P < .003). There was a nonsignificant reduction in the vasodilatory response to 8% carbon dioxide (mean: predrug, 87.7%; postdrug, 61.0%), with marked intersubject variability. In contrast, basal middle cerebral artery velocity and vasoconstrictor and vasodilatory responses to changes in carbon dioxide were unchanged after aspirin or sulindac administration.
The lack of effect of aspirin on basal cerebral blood flow velocity and on vasodilatory reserve is reassuring; aspirin will not reduce cerebral blood flow or the response to a reduced perfusion pressure in patients with critically impaired cerebral hemodynamics. However, indomethacin should be avoided in such patients.
前列腺素被认为在维持脑血流量以及可能在对二氧化碳的血管舒张反应中起重要作用。因此，抑制环氧化酶的非甾体抗炎药和阿司匹林可能会减少脑血流量以及对高碳酸血症的反应。这可能会在血流动力学临界循环的患者中诱发脑缺血。它还会干扰使用二氧化碳测量脑血管储备。
使用经颅多普勒超声对大脑中动脉进行测量，以评估单剂量吲哚美辛以及其他两种环氧化酶抑制剂（阿司匹林和舒林酸）对脑循环的影响。每个药物组研究7名正常成年人。测量静息血流速度以及对高碳酸血症和过度通气的反应。
吲哚美辛导致大脑中动脉基础血流速度从平均48.9厘米/秒降至34.0厘米/秒（P <.002）。它还将对低碳酸血症（由过度通气诱发）的血管收缩反应从37.5%降至20.7%（P <.003）。对8%二氧化碳的血管舒张反应有非显著性降低（平均值：用药前87.7%；用药后61.0%），个体间差异显著。相比之下，服用阿司匹林或舒林酸后，大脑中动脉基础速度以及对二氧化碳变化的血管收缩和血管舒张反应未改变。
阿司匹林对基础脑血流速度和血管舒张储备缺乏影响令人放心；阿司匹林不会降低脑血流动力学严重受损患者的脑血流量或对灌注压降低的反应。然而，此类患者应避免使用吲哚美辛。
