Department of Anaesthesiology, University Medical Centre of the Johannes Gutenberg-University, Germany.
Br J Anaesth. 2011 Nov;107(5):735-41. doi: 10.1093/bja/aer227. Epub 2011 Jul 31.
Propofol reduces cerebral blood flow (CBF) secondary to cerebral metabolic depression. However, in vitro and in vivo studies demonstrate that propofol directly dilates the vascular smooth muscle. This study investigates the effects of propofol-induced changes in bispectral index (BIS) on cerebral microcirculation and oxygenation during craniotomies.
In 21 craniotomy patients undergoing routine craniotomy, anaesthesia was maintained with propofol 4-10 mg kg⁻¹ h⁻¹ and remifentanil 0.1-0.4 µg kg⁻¹ min⁻¹. Propofol concentration was adjusted to achieve higher BIS (target 40) or lower BIS (target 20). Regional measurements of capillary venous blood flow (rvCBF), oxygen saturation (srvO₂), and haemoglobin amount (rvHb) at 2 mm (grey matter) and 8 mm (white matter) cerebral depth were randomly performed at higher and lower BIS by combined laser-Doppler flowmetry and spectroscopy. Calculations: approximated arteriovenous difference in oxygen content (avDO₂) and cerebral metabolic rate of oxygen (aCMRO₂).
mean values (sd).
Mann-Whitney test (*P<0.05). Results Human cerebral microcirculation and oxygen saturation were assessed at propofol dosages 5.1 (2.3) mg kg⁻¹ h⁻¹ [BIS 40 (9)] and 7.8 (2.1) mg kg⁻¹ h⁻¹ [BIS 21 (7)]. Propofol-induced reduction in BIS resulted in increased srvO₂ (P=0.018), and decreased avDO₂ (P=0.025) and aCMRO(2) (P=0.022), in 2 mm cerebral depth, while rvCBF and rvHb remained unchanged. In 8 mm cerebral depth, srvO₂, rvCBF, rvHb, and also calculated parameters avDO₂ and aCMRO₂ remained unaltered.
Findings suggest alteration of the CBF/CMRO₂ ratio by propofol in cortical brain regions; therefore, it might be possible that propofol affects coupling of flow and metabolism in the cerebral microcirculation.
异丙酚通过降低脑代谢来减少脑血流（CBF）。然而，体外和体内研究表明，异丙酚可直接舒张血管平滑肌。本研究旨在探讨异丙酚诱导的脑电双频指数（BIS）变化对开颅术中脑微循环和氧合的影响。
21 例行常规开颅术的开颅术患者，麻醉维持用异丙酚 4-10mg/kg/h 和瑞芬太尼 0.1-0.4μg/kg/min。调整异丙酚浓度以达到较高的 BIS（目标 40）或较低的 BIS（目标 20）。通过激光多普勒血流测量和光谱测量，随机在较高和较低的 BIS 下对 2mm（灰质）和 8mm（白质）脑深度的毛细血管静脉血流（rvCBF）、氧饱和度（srvO₂）和血红蛋白量（rvHb）进行区域性测量。计算：近似动静脉血氧含量差（avDO₂）和脑氧代谢率（aCMRO₂）。
平均值（标准差）。
Mann-Whitney 检验（*P<0.05）。结果：人类脑微循环和氧饱和度在异丙酚剂量 5.1（2.3）mg/kg/h [BIS 40（9）]和 7.8（2.1）mg/kg/h [BIS 21（7）]下进行评估。BIS 诱导的异丙酚降低导致 2mm 脑深度的 srvO₂增加（P=0.018），avDO₂减少（P=0.025）和 aCMRO₂减少（P=0.022），而 rvCBF 和 rvHb 保持不变。在 8mm 脑深度，srvO₂、rvCBF、rvHb 以及计算的参数 avDO₂和 aCMRO₂均未改变。
结果表明异丙酚在皮质脑区改变了 CBF/CMRO₂ 比值；因此，异丙酚可能影响脑微循环的血流和代谢的耦联。
