Faria Carine Carrijo de, Mendes Pedro Vitale, Maia Junior Luis Carlos Cardoso, Kreling Gabriel Afonso Dutra, Park Marcelo
Intensive Care Unit, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo - São Paulo (SP), Brazil.
Crit Care Sci. 2025 Jul 11;37:e20250373. doi: 10.62675/2965-2774.20250373. eCollection 2025.
In recent years, venovenous extracorporeal membrane oxygenation has become a critical therapeutic tool for patients with severe respiratory failure. Neurological complications, including brain death, are common in this population, and confirming brain death in venovenous extracorporeal membrane oxygenation-supported patients presents unique challenges. In Brazil, an apnea test is mandatory for confirming brain death. However, its application in patients on venovenous extracorporeal membrane oxygenation, which predominantly addresses venoarterial extracorporeal membrane oxygenation cases, is not well defined in the literature. This report outlines our standardized approach for conducting apnea tests in three patients with suspected brain death during ongoing venovenous extracorporeal membrane oxygenation support. We describe three cases from a cohort of 93 extracorporeal membrane oxygenation patients treated for severe respiratory failure. The apnea test was conducted after 24 hours of observation without sedation. Given the physiological nuances of extracorporeal membrane oxygenation, where carbon dioxide clearance is primarily influenced by sweep flow, we adopted a low-sweep-flow protocol (200mL/minute) to achieve a partial pressure of carbon dioxide greater than 55mmHg, consistent with brain death criteria. In cases of severe hypoxemia during the test, extracorporeal membrane oxygenation blood flow can be temporarily increased to maintain oxygenation. All patients received concurrent renal support, which also facilitated carbon dioxide clearance. Our findings suggest that the apnea test with very low sweep flow is a safe and feasible method for diagnosing brain death in venovenous extracorporeal membrane oxygenation-supported patients. This physiologically grounded approach provides a clinically viable strategy for managing the complex interplay between gas exchange, oxygenation, and carbon dioxide clearance during the apnea test.
近年来，静脉-静脉体外膜肺氧合已成为治疗严重呼吸衰竭患者的关键治疗手段。包括脑死亡在内的神经系统并发症在这一群体中很常见，而在接受静脉-静脉体外膜肺氧合支持的患者中确认脑死亡面临着独特的挑战。在巴西，进行呼吸暂停试验是确认脑死亡的必要条件。然而，其在主要针对静脉-动脉体外膜肺氧合病例的静脉-静脉体外膜肺氧合患者中的应用，在文献中并未明确界定。本报告概述了我们在三名接受持续静脉-静脉体外膜肺氧合支持且疑似脑死亡的患者中进行呼吸暂停试验的标准化方法。我们描述了93例因严重呼吸衰竭接受体外膜肺氧合治疗的患者队列中的三例。在无镇静状态下观察24小时后进行呼吸暂停试验。鉴于体外膜肺氧合的生理细微差别，即二氧化碳清除主要受扫气流量影响，我们采用低扫气流量方案（200毫升/分钟）以实现二氧化碳分压大于55毫米汞柱，这符合脑死亡标准。在试验过程中出现严重低氧血症的情况下，可暂时增加体外膜肺氧合血流量以维持氧合。所有患者均同时接受肾脏支持，这也有助于二氧化碳清除。我们的数据表明，极低扫气流量的呼吸暂停试验是在接受静脉-静脉体外膜肺氧合支持的患者中诊断脑死亡的一种安全可行的方法。这种基于生理学的方法为在呼吸暂停试验期间管理气体交换、氧合和二氧化碳清除之间复杂的相互作用提供了一种临床可行的策略。
