Department of Anesthesiology and Intensive Care, University Hospital of Toulouse, University Paul Sabatier, Toulouse, France,
Neurocrit Care. 2013 Oct;19(2):215-7. doi: 10.1007/s12028-013-9845-y.
Apnea test is a key component to confirm brain death. For patients receiving extracorporeal membrane oxygenation (ECMO), apnea test remains challenging. Brain death (BD) diagnosis is often made without apnea test.
We report the case of a 29-year-old man presenting clinical signs of BD while treated with ECMO therapy for refractory cardiogenic shock. Decreasing the ECMO sweep gas flow from 3 to 1 L/min and increasing oxygen delivery to 100% on ECMO during the apnea test have allowed increasing the PaCO2 of more than 20 mmHg without decreasing PaO2.
In order to diagnose BD, neurological examination should be complete, including apnea testing, which can be not possible in patients receiving ECMO due to CO2 removal from the membrane. Decreasing sweep gas rate allows reduction in CO2 diffusion through the membrane. However, decreasing the ECMO gas flow to zero could be insufficient to maintain normoxemia. Decreasing (but not stopping) the sweep gas flow to 1 L/min and increasing the oxygen delivery through the ECMO have allowed performing the apnea test safely.
To assess brain death in patients on ECMO, apnea test can be performed without compromising oxygenation by decreasing (but not stopping) the sweep gas flow and increasing oxygen delivery through the membrane.
呼吸暂停试验是确认脑死亡的关键组成部分。对于接受体外膜肺氧合（ECMO）治疗的患者，呼吸暂停试验仍然具有挑战性。脑死亡（BD）的诊断通常在没有进行呼吸暂停试验的情况下做出。
我们报告了一例 29 岁男性的病例，该患者在接受 ECMO 治疗难治性心源性休克时出现 BD 的临床体征。在呼吸暂停试验期间，将 ECMO 的吹扫气体流量从 3 降至 1 L/min，并将 ECMO 上的氧气输送增加到 100%，从而使 PaCO2 增加超过 20mmHg，而不降低 PaO2。
为了诊断 BD，应进行完整的神经系统检查，包括呼吸暂停试验，但由于膜去除 CO2，接受 ECMO 治疗的患者可能无法进行呼吸暂停试验。降低吹扫气体速度可减少 CO2 通过膜的扩散。然而，将 ECMO 气体流量降低至零可能不足以维持正常氧合。将吹扫气体流量降低（但不停止）至 1 L/min，并通过 ECMO 增加氧气输送，可安全进行呼吸暂停试验。
为了评估 ECMO 患者的脑死亡，可以通过降低（但不停）吹扫气体流量并通过膜增加氧气输送来进行呼吸暂停试验，而不会影响氧合。
