Unidade de Terapia Intensiva Neurológica, Hospital Beneficência Portuguesa, São Paulo, SP, Brasil.
Rev Bras Ter Intensiva. 2020 Jun;32(2):312-318. doi: 10.5935/0103-507x.20200048. Epub 2020 Jul 13.
Among the potential complications of extracorporeal membrane oxygenation, neurological dysfunctions, including brain death, are not negligible. In Brazil, the diagnostic process of brain death is regulated by Federal Council of Medicine resolution 2,173 of 2017. Diagnostic tests for brain death include the apnea test, which assesses the presence of a ventilatory response to hypercapnic stimulus. However, gas exchange, including carbon dioxide removal, is maintained under extracorporeal membrane oxygenation, making the test challenging. In addition to the fact that the aforementioned resolution does not consider the specificities of the diagnostic process under extracorporeal membrane oxygenation, studies on the subject are scarce. This review aims to identify case studies (and/or case series) published in the PubMed® and Cochrane databases describing the process of brain death diagnosis. A total of 17 publications (2011 - 2019) were identified. The practical strategies described were to provide pretest supplemental oxygenation via mechanical ventilation and extracorporeal membrane oxygenation (fraction of inspired oxygen = 1.0) and, at the beginning of the test, titrate the sweep flow (0.5 - 1.0L/minute) to minimize carbon dioxide removal. It is also recommended to increase blood flow and/or sweep flow in the presence of hypoxemia and/or hypotension, which may be combined with fluid infusion and/or the escalation of inotropic/vasoactive drugs. If the partial pressure of carbon dioxide threshold is not reached, repeating the test under supplementation of carbon dioxide exogenous to the circuit is an alternative. Last, in cases of venoarterial extracorporeal membrane oxygenation, to measure gas variation and exclude differential hypoxia, blood samples of the native and extracorporeal (post-oxygenator) circulations are recommended.
在体外膜肺氧合的潜在并发症中，神经功能障碍，包括脑死亡，不容忽视。在巴西，脑死亡的诊断过程由 2017 年联邦医学理事会第 2173 号决议监管。脑死亡的诊断测试包括 apnea 测试，评估对高碳酸刺激的通气反应。然而，体外膜肺氧合下维持着气体交换，包括二氧化碳的去除，这使得测试具有挑战性。除了上述决议没有考虑体外膜肺氧合下诊断过程的特殊性之外，关于这个主题的研究也很少。本综述旨在确定在 PubMed®和 Cochrane 数据库中发表的描述脑死亡诊断过程的病例研究（和/或病例系列）。共确定了 17 篇出版物（2011-2019 年）。描述的实用策略是通过机械通气和体外膜肺氧合提供预测试补充氧气（吸入氧气分数=1.0），并在测试开始时调整吹扫流量（0.5-1.0L/分钟）以最小化二氧化碳的去除。还建议在存在低氧血症和/或低血压的情况下增加血流量和/或吹扫流量，这可能与液体输注和/或正性肌力/血管活性药物的升级相结合。如果未达到二氧化碳分压阈值，则可选择在补充回路外源性二氧化碳的情况下重复测试。最后，在静脉-动脉体外膜肺氧合的情况下，为了测量气体变化并排除差异缺氧，建议采集原生和体外（氧合后）循环的血液样本。
