Division of NeuroIntensive Care, Department of Anesthesia and Critical Care, Ospedale San Gerardo, Monza, Italy.
Crit Care Med. 2012 Oct;40(10):2797-804. doi: 10.1097/CCM.0b013e31825b8bc6.
Isoflurane is a volatile anesthetic that has a vasodilating effect on cerebral vessels producing a cerebral blood flow increase. Furthermore, it has been shown in animal studies that isoflurane, when used as a preconditioning agent, has neuroprotective properties, inducing tolerance to ischemia. However, it is not routinely used in neurointensive care because of the potential increase in intracranial pressure caused by the rise in cerebral blood flow. Nevertheless, subarachnoid hemorrhage patients who are at risk for vasospasm may benefit from an increase in cerebral blood flow. We measured regional cerebral blood flow during intravenous sedation with propofol and during sedation with isoflurane in patients with severe subarachnoid hemorrhage not having intracranial hypertension.
The study is a crossover, open clinical trial (NCT00830843).
Neurointensive care unit of an academic hospital.
Thirteen patients with severe subarachnoid hemorrhage, (median Fisher scale 4), monitored on clinical indication with intracranial pressure device and a thermal diffusion probe for the assessment of regional cerebral blood flow. An intracranial pressure>18 mm Hg was an exclusion criterion.
Cerebral and hemodynamic variables were assessed at three steps. Step 1: sedation with propofol 3-4 mg/kg/hr; step 2: after 1 hr of propofol discontinuation and isoflurane 0.8%; step 3: after 1 hr of propofol at the same previous infusion rate. Cerebral perfusion pressure and arterial PCO2 were maintained constant. Mean cerebral artery flow velocity and jugular vein oxygen saturation were measured at the end of each step.
Regional cerebral blood flow increased significantly during step 2 (39.3±29 mL/100 hg/min) compared to step 1 (20.8±10.7) and step 3 (24.7±8). There was no difference in regional cerebral blood flow comparing step 1 vs. step 3. No significant difference in intracranial pressure, mean cerebral artery transcranial Doppler velocity, PaCO2, cerebral perfusion pressure between the different steps.
Isoflurane increases regional cerebral blood flow in comparison to propofol. Intracranial pressure did not change significantly in the population not affected by intracranial hypertension.
异氟醚是一种挥发性麻醉剂，它对脑血管有扩张作用，导致脑血流增加。此外，动物研究表明，异氟醚作为预处理剂具有神经保护作用，诱导对缺血的耐受。然而，由于脑血流增加导致颅内压升高的潜在风险，它并未在神经重症监护中常规使用。然而，蛛网膜下腔出血患者存在血管痉挛的风险，可能受益于脑血流的增加。我们在没有颅内高压的严重蛛网膜下腔出血患者中，测量了异丙酚静脉镇静期间和异氟醚镇静期间的局部脑血流。
该研究是一项交叉、开放的临床试验（NCT00830843）。
学术医院的神经重症监护病房。
13 名严重蛛网膜下腔出血患者（中位数 Fisher 分级 4 级），根据颅内压装置和用于评估局部脑血流的热扩散探头的临床指征进行监测。颅内压>18mmHg 是排除标准。
在三个步骤评估脑和血流动力学变量。步骤 1：异丙酚 3-4mg/kg/hr 镇静；步骤 2：异丙酚停药 1 小时后和异氟醚 0.8%；步骤 3：异丙酚以相同的先前输注速率恢复。保持脑灌注压和动脉 PCO2 恒定。在每个步骤结束时测量平均大脑中动脉血流速度和颈静脉血氧饱和度。
与步骤 1（20.8±10.7）和步骤 3（24.7±8）相比，步骤 2（39.3±29 mL/100 hg/min）中局部脑血流显著增加。步骤 1 与步骤 3 相比，局部脑血流无差异。不同步骤之间，颅内压、平均大脑中动脉经颅多普勒速度、PaCO2、脑灌注压无显著差异。
与异丙酚相比，异氟醚增加局部脑血流。未受颅内高压影响的人群中，颅内压无显著变化。
