Effect of dexmedetomidine on cerebral blood flow velocity, cerebral metabolic rate and carbon dioxide response in normal humans
Effect of dexmedetomidine on cerebral blood flow velocity, cerebral metabolic rate and carbon dioxide response in normal humans
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DOI：
10.1097/01.anes.0000299576.00302.4c
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发表时间：
2008-02-01
期刊：
影响因子：
8.8
通讯作者：
Patel, Piyush M.
中科院分区：
文献类型：
--
作者：
Drummond, John C.;Dao, Andrew V.;Patel, Piyush M.
背景：右美托咪定可降低人和动物的脑血流量（CBF）。在动物研究中，脑代谢率（CMR）无变化。因此，作者假设右美托咪定会导致CBF/CMR比值降低，叠加过度通气会进一步降低。这种减少可能是有害的患者神经injury.Methods：大脑中动脉血流速度（CBFV）连续记录在6名志愿者。在右美托咪定给药前、给药期间和给药后的6个时间点测定CBFV、颈静脉球静脉饱和度（Sjvo（2））、CMR当量（CMRe）和CBFV/CMRc比值：（1）预处理;（2）预处理伴过度通气;稳态血浆水平为（3）0.6 ng/ml和（4）1.2 ng/ml;（5）1.2 ng/ml伴过度通气;（6）停用右美托咪定后30 min。结果：CBFV和CMRe呈剂量依赖性降低，在1.2ng/ml时，CBFV和CMRe呈剂量依赖性降低。CBFV/CMRe比值不变。CBFV对二氧化碳的反应从1.20 +/- 0.2 cm中心点s（-1）中心点mmHg-1降低到0.40 +/- 0.15 cm中心点s（-1）中心点mmHg-1（1.2 ng/ml）。在过度通气期间，Sjvo（2）在1.2 ng/ml与预处理时相比在统计学上没有变化（50 +/- 11 vs. 43 +/- 5%）。1.2 ng/ml的过度通气引起的唤醒导致CBFV（30 5 ~ 38 4）和脑电双频指数（43 ± 10 ~ 94 ± 3）增加。结论：由于CMRe的意外降低和Paco 2-CBFV关系斜率的降低，未观察到CBFV/CMRe比值的预期降低。在1.2 ng/ml时过度通气唤醒期间CBFV和脑电双频指数增加，表明在右美托咪定给药期间CMR-CBr偶联得以保留。在神经损伤患者中进一步评价右美托咪定似乎是合理的。
Background: Dexmedetomidine reduces cerebral blood flow (CBF) in humans and animals. In animal investigations, cerebral metabolic rate (CMR) was unchanged. Therefore, the authors hypothesized that dexmedetomidine would cause a decrease in the CBF/CMR ratio with even further reduction by superimposed hyperventilation. This reduction might be deleterious in patients with neurologic injuries.Methods: Middle cerebral artery velocity (CBFV) was recorded continuously in six volunteers. CBFV, jugular bulb venous saturation (Sjvo(2)), CMR equivalent (CMRe), and CBFV/CMRc ratio were determined at six intervals before, during, and after administration of dexmedetomidine: (1) presedation; (2) presedation with hyperventilation; at steady state plasma levels of (3) 0.6 ng/ml and (4) 1.2 ng/ml; (5) 1.2 ng/ml with hyperventilation; and (6) 30 min after discontinuing dexmedetomidine. The slope of the arterial carbon dioxide tension (Paco(2))-CBFV relation was determined presedation and at 1.2 ng/ml.Results: CBFV and CMRe decreased in a dose-related manner. The CBFV/CMRe ratio was unchanged. The CBFV response to carbon dioxide decreased from 1.20 +/- 0.2 cm center dot s(-1)center dot mm Hg-1 presedation to 0.40 +/- 0.15 cm center dot s(-1)center dot mm Hg-1 at 1.2 ng/ml. Sjvo(2) was statistically unchanged during hyperventilation at 1.2 ng/ml versus presedation (50 +/- 11 vs. 43 +/- 5%). Arousal for hyperventilation at 1.2 ng/ml resulted in increased CBFV (30 5 to 38 4) and Bispectral index (43 +/- 10 to 94 +/- 3).Conclusions: The predicted decrease in CBFV/CMRe ratio was not observed because of an unanticipated reduction of CMRe and a decrease in the slope of the Paco(2)-CBFV relation. CBFV and Bispectral index increases during arousal for hyperventilation at 1.2 ng/ml suggest that CMR-CBr coupling is preserved during dexmedetomidine administration. Further evaluation of dexmedetomidine in patients with neurologic injuries seems justified.