Department of Anesthesiology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
Neurocrit Care. 2012 Aug;17(1):77-84. doi: 10.1007/s12028-012-9721-1.
Clinical monitoring of cerebral blood flow (CBF) autoregulation in patients undergoing liver transplantation may provide a means for optimizing blood pressure to reduce the risk of brain injury. The purpose of this pilot project is to test the feasibility of autoregulation monitoring with transcranial Doppler (TCD) and near-infrared spectroscopy (NIRS) in patients undergoing liver transplantation and to assess changes that may occur perioperatively.
We performed a prospective observational study in 9 consecutive patients undergoing orthotopic liver transplantation. Patients were monitored with TCD and NIRS. A continuous Pearson's correlation coefficient was calculated between mean arterial pressure (MAP) and CBF velocity and between MAP and NIRS data, rendering the variables mean velocity index (Mx) and cerebral oximetry index (COx), respectively. Both Mx and COx were averaged and compared during the dissection phase, anhepatic phase, first 30 min of reperfusion, and remaining reperfusion phase. Impaired autoregulation was defined as Mx ≥ 0.4.
Autoregulation was impaired in one patient during all phases of surgery, in two patients during the anhepatic phase, and in one patient during reperfusion. Impaired autoregulation was associated with a MELD score >15 (p = 0.015) and postoperative seizures or stroke (p < 0.0001). Analysis of Mx categorized in 5 mmHg bins revealed that MAP at the lower limit of autoregulation (MAP when Mx increased to ≥ 0.4) ranged between 40 and 85 mmHg. Average Mx and average COx were significantly correlated (p = 0.0029). The relationship between COx and Mx remained when only patients with bilirubin >1.2 mg/dL were evaluated (p = 0.0419). There was no correlation between COx and baseline bilirubin (p = 0.2562) but MELD score and COx were correlated (p = 0.0458). Average COx was higher for patients with a MELD score >15 (p = 0.073) and for patients with a neurologic complication than for patients without neurologic complications (p = 0.0245).
These results suggest that autoregulation is impaired in patients undergoing liver transplantation, even in the absence of acute, fulminant liver failure. Identification of patients at risk for neurologic complications after surgery may allow for prompt neuroprotective interventions, including directed pressure management.
对接受肝移植的患者进行脑血流（CBF）自动调节的临床监测，可能为优化血压以降低脑损伤风险提供一种手段。本初步研究的目的是测试经颅多普勒（TCD）和近红外光谱（NIRS）监测在接受肝移植的患者中监测自动调节的可行性，并评估围手术期可能发生的变化。
我们对 9 例连续接受原位肝移植的患者进行了前瞻性观察性研究。患者接受 TCD 和 NIRS 监测。计算平均动脉压（MAP）与 CBF 速度之间以及 MAP 与 NIRS 数据之间的连续 Pearson 相关系数，分别得出变量平均速度指数（Mx）和脑氧饱和度指数（COx）。分别对解剖阶段、无肝期、再灌注的前 30 分钟和剩余再灌注期进行 Mx 和 COx 平均值比较。自动调节受损定义为 Mx≥0.4。
1 例患者在手术的所有阶段、2 例患者在无肝期和 1 例患者在再灌注期间自动调节受损。自动调节受损与 MELD 评分>15（p=0.015）和术后癫痫发作或中风（p<0.0001）相关。将 Mx 分为 5mmHg -bin 进行分析显示，自动调节下限的 MAP（当 Mx 增加到≥0.4 时的 MAP）范围在 40 至 85mmHg 之间。平均 Mx 和平均 COx 显著相关（p=0.0029）。仅评估胆红素>1.2mg/dL 的患者时，COx 与 Mx 的关系仍然存在（p=0.0419）。COx 与基线胆红素无相关性（p=0.2562），但 MELD 评分与 COx 相关（p=0.0458）。MELD 评分>15 的患者（p=0.073）和有神经系统并发症的患者的平均 COx 高于无神经系统并发症的患者（p=0.0245）。
这些结果表明，即使在没有急性暴发性肝功能衰竭的情况下，接受肝移植的患者也会出现自动调节受损。识别术后发生神经并发症的高危患者可能允许及时进行神经保护干预，包括靶向血压管理。
