Department of Neurology, Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, 600 N Wolfe Street, Phipps 455, Baltimore, MD, 21287, USA.
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
Neurocrit Care. 2017 Dec;27(3):362-369. doi: 10.1007/s12028-017-0421-8.
Transcranial Doppler (TCD) noninvasively measures cerebral blood flow (CBF) velocity and is a well-studied method to monitor cerebral autoregulation (CA). Near-infrared spectroscopy (NIRS) has emerged as a promising noninvasive method to determine CA continuously by using regional cerebral oxygen saturation (rSO) as a surrogate for CBF. Little is known about its accuracy to determine CA in patients with intracranial lesions. The purpose of this study was to assess the accuracy of rSO-based CA monitoring with TCD methods in comatose patients with acute neurological injury.
Thirty-three comatose patients were monitored at the bedside to measure CA using both TCD and NIRS. Patients were monitored daily for up to three days from coma onset. The cerebral oximetry index (COx) was calculated as the moving correlation between the slow waves of rSO and mean arterial pressure (MAP). The mean velocity index (Mx) was calculated as a similar coefficient between slow waves of TCD-measured CBF velocity and MAP. Optimal blood pressure was defined as the MAP with the lowest Mx and COx. Averaged Mx and COx as well as optimal MAP, based on both Mx and COx, were compared using Pearson's correlation. Bias analysis was performed between these same CA metrics.
The median duration of monitoring was 60 min (interquartile range [IQR] 48-78). There was a moderate correlation between the averaged values of COx and Mx (R = 0.40, p = 0.005). Similarly, there was a strong correlation between optimal MAP calculated for COx and Mx (R = 0.87, p < 0.001). Bland-Altman analysis showed moderate agreement with bias (±standard deviation) of -0.107 (±0.191) for COx versus Mx and good agreement with bias of 1.90 (±7.94) for optimal MAP determined by COx versus Mx.
Monitoring CA with NIRS-derived COx is correlated and had good agreement with previously validated TCD-based method. These results suggest that COx may be an acceptable substitute for Mx monitoring in patients with acute intracranial injury.
经颅多普勒（TCD）可无创测量脑血流速度，是一种研究较为深入的脑自动调节（CA）监测方法。近红外光谱（NIRS）已成为一种有前途的连续测量 CA 的非侵入性方法，通过区域性脑氧饱和度（rSO）作为脑血流的替代物来确定 CA。目前尚不清楚它在颅内病变患者中确定 CA 的准确性。本研究旨在评估基于 TCD 方法的 rSO 监测 CA 在急性神经损伤昏迷患者中的准确性。
33 例昏迷患者在床边进行监测，使用 TCD 和 NIRS 测量 CA。患者从昏迷开始每天监测最多三天。脑氧合指数（COx）的计算方法是 rSO 慢波与平均动脉压（MAP）之间的移动相关性。平均速度指数（Mx）的计算方法是 TCD 测量的脑血流速度慢波与 MAP 之间相似的系数。最优血压定义为 Mx 和 COx 最低的 MAP。基于 Mx 和 COx 的平均 Mx 和 COx 以及最优 MAP 进行 Pearson 相关性比较。对这些 CA 指标进行偏倚分析。
监测中位数时间为 60 分钟（四分位距 [IQR] 48-78）。COx 和 Mx 的平均值之间存在中度相关性（R=0.40，p=0.005）。同样，COx 和 Mx 计算的最优 MAP 之间存在很强的相关性（R=0.87，p<0.001）。Bland-Altman 分析显示，COx 与 Mx 的偏差（±标准偏差）为-0.107（±0.191），具有中等一致性，COx 与 Mx 相比，最优 MAP 的偏差为 1.90（±7.94），一致性良好。
NIRS 衍生的 COx 监测 CA 与已验证的基于 TCD 的方法相关且具有良好的一致性。这些结果表明，在急性颅内损伤患者中，COx 可能是 Mx 监测的可接受替代物。
