Kramer Andreas H, Roberts Derek J
Departments of Critical Care Medicine & Clinical Neurosciences, Foothills Hospital, University of Calgary, McCaig Tower, 3134 Hospital Drive N.W., Calgary, AB, T2N 2T9, Canada,
Neurocrit Care. 2014 Dec;21(3):539-50. doi: 10.1007/s12028-014-9997-4.
Physiological instability and confounding factors may interfere with the clinical diagnosis of brain death. Computed tomography angiography (CTA) has been suggested as a potential ancillary test for confirmation of brain death, but its diagnostic accuracy remains unclear.
We searched MEDLINE, EMBASE, and CENTRAL for studies comparing CTA with other accepted methods of diagnosing brain death (clinical or radiographic). Summary estimates of diagnostic accuracy were computed using random effects models. Subgroup analyses and meta-regression were performed to assess associations between CTA sensitivity and study or patient characteristics.
Twelve studies, involving 541 patients, were included. If the CTA criterion for brain death was complete lack of opacification of intracranial vessels, then the pooled sensitivity was 62 % (50-74 %) for venous phase and 84 % (75-94 %) for arterial phase imaging. The sensitivity of CTA was higher when the criterion for brain death involved absence of opacification of internal cerebral veins, either alone (99 %, 97-100 %) or in combination with lack of flow to the distal middle cerebral artery branches (85 %, 77-93 %). CTA sensitivity was not influenced by different reference standards (clinical vs. radiographic) or predominant diagnostic category (stroke vs. brain trauma). Specificity of CTA could not be adequately determined from the existing data.
Many patients who progress to brain death by accepted clinical or radiographic criteria have persistent opacification of proximal intracranial vessels when CTA is performed. The specificity of CTA in the diagnosis of brain death has not been adequately assessed. Routine use of CTA as an ancillary test in the diagnosis of brain death is therefore not recommended until diagnostic criteria have undergone further refinement and prospective validation. Absence of opacification of the internal cerebral veins appears to be the most promising angiographic criterion.
生理不稳定和混杂因素可能会干扰脑死亡的临床诊断。计算机断层血管造影（CTA）已被提议作为确认脑死亡的一种潜在辅助检查，但它的诊断准确性仍不明确。
我们检索了MEDLINE、EMBASE和CENTRAL数据库，以查找比较CTA与其他公认的脑死亡诊断方法（临床或影像学方法）的研究。使用随机效应模型计算诊断准确性的汇总估计值。进行亚组分析和meta回归，以评估CTA敏感性与研究或患者特征之间的关联。
纳入了12项研究，涉及541例患者。如果脑死亡的CTA标准是颅内血管完全不显影，那么静脉期成像的汇总敏感性为62%（50%-74%），动脉期成像的汇总敏感性为84%（75%-94%）。当脑死亡标准涉及单独的大脑内静脉不显影（99%，97%-100%）或与大脑中动脉远端分支血流缺失相结合（85%，77%-93%）时，CTA的敏感性更高。CTA敏感性不受不同参考标准（临床与影像学）或主要诊断类别（中风与脑外伤）的影响。现有数据无法充分确定CTA的特异性。
许多按照公认的临床或影像学标准进展至脑死亡的患者在进行CTA检查时，颅内近端血管仍持续显影。CTA在脑死亡诊断中的特异性尚未得到充分评估。因此在诊断标准经过进一步完善和前瞻性验证之前，不建议常规使用CTA作为脑死亡诊断的辅助检查。大脑内静脉不显影似乎是最有前景的血管造影标准。
