Tackla Ryan, Hinzman Jason M, Foreman Brandon, Magner Mark, Andaluz Norberto, Hartings Jed A
Department of Neurosurgery, University of Cincinnati (UC) College of Medicine, Neurotrauma Center at UC Neuroscience Institute, 231 Albert Sabin Way, Cincinnati, OH, 45267, USA.
Mayfield Clinic, Cincinnati, OH, USA.
Neurocrit Care. 2015 Dec;23(3):339-46. doi: 10.1007/s12028-015-0146-5.
Impairment of cerebrovascular autoregulation is a risk factor for ischemic damage following severe brain injury. Autoregulation can be assessed indirectly using intracranial pressure monitoring as a surrogate of cerebral blood volume, but this measure may not be applicable to patients following decompressive craniectomy. Here, we describe assessment of autoregulation using regional cerebral blood flow (rCBF).
In seven patients with severe brain trauma who underwent neurological surgery, a Hemedex® rCBF probe was placed intraoperatively in peri-lesional tissue. Autoregulation was assessed as a moving Pearson correlation between CPP and rCBF (rCBFx).
Composite data from all patients showed relatively constant perfusion over a wide CPP range (50-90 mmHg) and a U-shaped autoregulation curve with maximal autoregulation (CPPopt) at 55-60 mmHg. All rCBF values fell below the ischemic threshold (<18 ml/100 g/min) when CPPs were <50 mmHg compared with 11 % ischemia when CPPs >50 mmHg (P < 0.05). We examined the percent time during which both autoregulation was intact and rCBF exceeded the ischemic threshold. In the composite data, this variable was maximal in the CPP range of 75-80 mmHg (CPPideal). In individual patients, the range of CPPs with intact autoregulation varied widely. Individual CPPopt values ranged between 60 and 100 mmHg and CPPideal ranged between 65 and 105 mmHg.
Assessment of autoregulation with Hemedex® rCBF monitor is feasible and could be used to guide CPP management strategies to optimize both autoregulation and perfusion. Autoregulatory impairment and CPPopt vary considerably between patients, and the addition of rCBF monitoring could help guide CPP targeting decisions.
脑血管自动调节功能受损是重度脑损伤后缺血性损伤的一个危险因素。可通过颅内压监测间接评估自动调节功能，将其作为脑血容量的替代指标，但该方法可能不适用于减压颅骨切除术后的患者。在此，我们描述了使用局部脑血流量（rCBF）评估自动调节功能的方法。
对7例接受神经外科手术的重度脑外伤患者，术中在病灶周围组织放置Hemedex® rCBF探头。通过计算脑灌注压（CPP）与rCBF（rCBFx）之间的移动Pearson相关性来评估自动调节功能。
所有患者的综合数据显示，在较宽的CPP范围（50 - 90 mmHg）内灌注相对恒定，自动调节曲线呈U形，在55 - 60 mmHg时自动调节功能最佳（CPPopt）。当CPP < 50 mmHg时，所有rCBF值均低于缺血阈值（< 18 ml/100 g/min），而当CPP > 50 mmHg时，缺血发生率为11%（P < 0.05）。我们检查了自动调节功能完整且rCBF超过缺血阈值的时间百分比。在综合数据中，该变量在75 - 80 mmHg的CPP范围内最大（CPPideal）。在个体患者中，自动调节功能完整的CPP范围差异很大。个体CPPopt值在60至100 mmHg之间，CPPideal在65至105 mmHg之间。
使用Hemedex® rCBF监测仪评估自动调节功能是可行的，可用于指导CPP管理策略，以优化自动调节功能和灌注。患者之间自动调节功能受损情况和CPPopt差异很大，增加rCBF监测有助于指导CPP目标设定决策。
