Department of Social Medicine, Division of Hygiene, Nihon University School of Medicine, Tokyo, Japan.
Anesth Analg. 2010 Nov;111(5):1279-84. doi: 10.1213/ANE.0b013e3181f42fc0. Epub 2010 Sep 29.
Although midazolam and propofol reduce cerebral blood flow (CBF) similarly, they generate different effects on the autonomic nervous system and endothelium-induced relaxation. Midazolam induces sympathetic dominance, whereas propofol induces parasympathetic dominance. Midazolam has no effect on endothelium-dependent relaxation, whereas propofol suppresses endothelium-dependent relaxation. Moreover, midazolam apparently constricts cerebral arterioles. We therefore hypothesized that midazolam and propofol have different effects on dynamic cerebral autoregulation.
Ten healthy male subjects received midazolam, propofol, and placebo administrations in a randomized, single-blind, crossover study. The modified Observer's Assessment of Alertness/Sedation scale was used to assess sedation depth. After reaching a target depth of sedation (Observer's Assessment of Alertness/Sedation scale score 3, responds only after name is called loudly and/or repeatedly) or after 15 minutes of normal saline administration as placebo, dynamic cerebral autoregulation was evaluated by spectral and transfer function analyses between mean arterial blood pressure variability in the radial artery measured by tonometry, and CBF velocity variability in the middle cerebral artery measured by transcranial Doppler ultrasonography.
Steady-state CBF velocity decreased significantly with midazolam and propofol administration (significant interaction effects, P = 0.024). However, transfer function gain in the low-frequency range decreased significantly only with midazolam administration (significant interaction effects, P = 0.015), suggesting a reduced magnitude of transfer from mean arterial blood pressure oscillations to CBF fluctuations during midazolam sedation.
Our results suggest that midazolam and propofol sedation have different effects on dynamic cerebral autoregulation despite causing equivalent decreases in steady-state CBF velocity. Only midazolam sedation is likely to improve dynamic cerebral autoregulation.
尽管咪达唑仑和丙泊酚均可降低脑血流（CBF），但它们对自主神经系统和内皮细胞诱导的松弛产生不同的影响。咪达唑仑引起交感神经占优势，而丙泊酚引起副交感神经占优势。咪达唑仑对内皮依赖性松弛没有影响，而丙泊酚抑制内皮依赖性松弛。此外，咪达唑仑显然会收缩脑小动脉。因此，我们假设咪达唑仑和丙泊酚对动态脑自动调节有不同的影响。
10 名健康男性受试者接受咪达唑仑、丙泊酚和安慰剂的随机、单盲、交叉研究。使用改良的警觉/镇静观察者评估量表（Observer's Assessment of Alertness/Sedation scale）评估镇静深度。达到目标镇静深度（警觉/镇静观察者评估量表评分 3，仅在大声且/或重复呼叫姓名后才有反应）或在生理盐水 15 分钟作为安慰剂后，通过容积描记法测量桡动脉平均动脉血压变异性和经颅多普勒超声测量大脑中动脉 CBF 速度变异性之间的谱和传递函数分析评估动态脑自动调节。
咪达唑仑和丙泊酚给药后稳态 CBF 速度显著降低（有显著的交互作用，P = 0.024）。然而，只有咪达唑仑给药时低频范围的传递函数增益显著降低（有显著的交互作用，P = 0.015），这表明在咪达唑仑镇静期间，从平均动脉血压波动到 CBF 波动的传递幅度降低。
尽管咪达唑仑和丙泊酚镇静均导致稳态 CBF 速度相等降低，但我们的结果表明，它们对动态脑自动调节有不同的影响。只有咪达唑仑镇静可能会改善动态脑自动调节。
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