Ali Ahmed M, Green David, Zayed Hany, Halawa Mustafa, El-Sakka Karim, Rashid Hisham I
Department of Vascular Surgery, King's College Hospital, Denmark Hill, London SE5 9RS, UK.
Interact Cardiovasc Thorac Surg. 2011 Mar;12(3):454-7. doi: 10.1510/icvts.2010.235598. Epub 2010 Oct 22.
Selective shunting during carotid endarterectomy (CEA) is advocated to reduce shunt related stroke. Cerebral monitoring is essential for temporary carotid shunting. Many techniques are available for cerebral monitoring, however, none is superior to monitoring the patient's neurological status (awake testing) while performing the procedure under local anaesthesia (LA). Cerebral oximetry (CO) and trans-cranial Doppler (TCD) has previously been used to show the adequacy of cerebral circulation in patients undergoing CEA. The aim of this study is to assess the reliability of CO and TCD in predicting the need for shunting compared to the awake testing.
Patients scheduled for CEA under LA were included. Patients converted to general anaesthesia (GA) and patients with no TCD window were excluded from the study. The Somanetics INVOS(®) CO was used for ipsilateral cerebral monitoring in all patients, in addition to TCD and awake testing. The percentage fall in CO regional oxygen saturation (rSO(2)), and decline in the mean flow velocity (FVm) in TCD following carotid artery clamping recorded. A drop in rSO(2) of ≥20% or FVm of ≥50% was considered an indicator of cerebral ischaemia that may predict the need for carotid shunting. Patients only shunted based on awake testing.
Forty-nine patients underwent triple assessment. The median clamp time was 24 min. 8/49 patients (16.3%) needed carotid shunting based on awake testing. In this group, six patients had ≥20% drop in rSO(2), and ≥50% drop in FVm. However, two patients had a non-significant drop in both rSO(2) and FVm (false negative). In the non-shunted group (41/49), one patient had a significant drop in rSO(2) (false positive) while 10/41 patients had a >50% drop in FVm. This represents sensitivity of 75%, and specificity of 97.5% for CO compared to sensitivity of 75% and specificity of 75% for TCD in prediction of shunting. The positive predictive value and negative predictive value were 85.7 and 95.2%, respectively for CO, compared to 37.5 and 93.9% for TCD.
TCD is less accurate than CO in predicting the need for carotid shunting during CEA. A combination of both methods does not add to the accuracy of detecting the need for carotid shunting.
提倡在颈动脉内膜切除术（CEA）期间进行选择性分流以减少与分流相关的中风。脑监测对于临时颈动脉分流至关重要。有许多技术可用于脑监测，然而，在局部麻醉（LA）下进行手术时，没有一种技术优于监测患者的神经状态（清醒测试）。脑血氧饱和度测定（CO）和经颅多普勒（TCD）先前已被用于显示接受CEA患者的脑循环充足性。本研究的目的是评估与清醒测试相比，CO和TCD在预测分流需求方面的可靠性。
纳入计划在LA下进行CEA的患者。转为全身麻醉（GA）的患者和没有TCD窗口的患者被排除在研究之外。所有患者除了进行TCD和清醒测试外，还使用Somanetics INVOS（®）CO进行同侧脑监测。记录颈动脉夹闭后CO局部氧饱和度（rSO₂）的下降百分比以及TCD中平均流速（FVm）的下降情况。rSO₂下降≥20%或FVm下降≥50%被认为是脑缺血的指标，可能预测需要进行颈动脉分流。患者仅根据清醒测试进行分流。
49例患者接受了三项评估。中位夹闭时间为24分钟。8/49例患者（16.3%）根据清醒测试需要进行颈动脉分流。在该组中，6例患者rSO₂下降≥20%，FVm下降≥50%。然而，2例患者rSO₂和FVm均有不显著下降（假阴性）。在未分流组（41/49）中，1例患者rSO₂有显著下降（假阳性），而10/41例患者FVm下降>50%。与TCD预测分流的敏感性75%和特异性75%相比，CO预测分流的敏感性为75%，特异性为97.5%。CO的阳性预测值和阴性预测值分别为85.7%和95.2%，而TCD的阳性预测值和阴性预测值分别为37.5%和93.9%。
在预测CEA期间颈动脉分流需求方面，TCD不如CO准确。两种方法结合并不能提高检测颈动脉分流需求的准确性。
