Forster A, Juge O, Morel D
J Cereb Blood Flow Metab. 1983 Jun;3(2):246-9. doi: 10.1038/jcbfm.1983.33.
Although it is known that hypercarbia increases and benzodiazepines decrease cerebral blood flow (CBF), the effects of benzodiazepines on CBF responsiveness to CO2 are not well documented. The influence on CBF and CBF-CO2 sensitivity of placebo or midazolam, which is a new water-soluble benzodiazepine, was measured in eight healthy volunteers using the noninvasive 133Xe inhalation method for CBF determination. Under normocarbia, midazolam decreased CBF from 40.6 +/- 3.2 to 27.0 +/- 5.0 ml 100 g-1 min-1 (means +/- SD). At a later session under hypercarbia, CBF was 58.8 +/- 4.4 ml 100 g-1 min-1 after administration of placebo, and 49.1 +/- 10.2 ml 100 g-1 min-1 after midazolam. The mean of the slopes correlating PaCO2 and CBF was significantly steeper with midazolam (2.5 +/- 1.2 ml 100 g-1 min-1 mm Hg-1) than with placebo (1.5 +/- 0.4 ml 100 g-1 min-1 mm Hg-1). Our results suggest that midazolam may be a safe agent to use in patients with intracranial hypertension, since it decreases CBF and thus cerebral blood volume; however, it should be administered with caution in nonventilated patients with increased intracranial pressure, since its beneficial effects on cerebrovascular tone can be readily counteracted by the increase in arterial CO2 tension induced by this drug.
虽然已知高碳酸血症会增加脑血流量（CBF），而苯二氮䓬类药物会降低脑血流量，但苯二氮䓬类药物对CBF对二氧化碳反应性的影响尚无充分记录。使用无创吸入133Xe法测定CBF，在8名健康志愿者中测量了安慰剂或咪达唑仑（一种新型水溶性苯二氮䓬类药物）对CBF及CBF-CO2敏感性的影响。在正常碳酸血症下，咪达唑仑使CBF从40.6±3.2降至27.0±5.0 ml·100 g-1·min-1（均值±标准差）。在随后的高碳酸血症阶段，服用安慰剂后CBF为58.8±4.4 ml·100 g-1·min-1，服用咪达唑仑后为49.1±10.2 ml·100 g-1·min-1。与安慰剂（1.5±0.4 ml·100 g-1·min-1·mmHg-1）相比，咪达唑仑使动脉血二氧化碳分压（PaCO2）与CBF相关的斜率均值显著更陡（2.5±1.2 ml·100 g-1·min-1·mmHg-1）。我们的结果表明，咪达唑仑可能是颅内高压患者使用的安全药物，因为它会降低CBF，从而减少脑血容量；然而，对于颅内压升高的未通气患者应谨慎使用，因为该药物对脑血管张力的有益作用很容易被其诱导的动脉二氧化碳张力升高所抵消。
