Nattanmai Premkumar, Newey Christopher R, Singh Ishpreet, Premkumar Keerthivaas
Department of Neurology, University of Missouri, Columbia, MO, USA.
SAGE Open Med Case Rep. 2017 Jun 22;5:2050313X17716050. doi: 10.1177/2050313X17716050. eCollection 2017.
Apnea test is required as part of the brain death examination. The duration of the apnea test is variable but typically requires 8-10 min. Prolonged apnea tests have been reported in the setting of hypothermia. Here, we describe a case of prolonged duration of apnea test secondary to a phenomenon called cardiac ventilation.
The patient presented in coma with brainstem areflexia after having an intracerebral hemorrhage resulting in subfalcine, central, uncal, and tonsillar herniations. Confounding variables were excluded. Brain death testing was performed, and she was found to have brainstem areflexia. Pre-requisites for apnea test were then met.
Apnea testing, however, was prolonged at 110 min. When reconnected to ventilator, it was noted that she had small (30-35 cc) tidal volumes at a rate of her heart rate without respiratory effort. Ancillary testing with four-vessel cerebral angiogram confirmed cerebral circulatory arrest.
To our knowledge, this is the longest reported case of apnea testing during brain death testing. Variables known to cause a delay in the rise of carbon dioxide (PaCO) levels were excluded. We suspect the hyperdynamic cardiac state caused cardiac ventilations resulting in slow increase in carbon dioxide levels.
呼吸暂停试验是脑死亡检查的一部分。呼吸暂停试验的持续时间不一，但通常需要8 - 10分钟。已有报道在体温过低的情况下呼吸暂停试验时间延长。在此，我们描述一例因一种称为心脏通气的现象导致呼吸暂停试验时间延长的病例。
该患者在脑出血后出现昏迷，伴有脑干反射消失，导致大脑镰下、中央、钩回和小脑扁桃体疝形成。排除了混杂变量。进行了脑死亡测试，发现她存在脑干反射消失。随后满足了呼吸暂停试验的先决条件。
然而，呼吸暂停试验延长至110分钟。当重新连接呼吸机时，注意到她在心率的频率下有小潮气量（30 - 35毫升），且无呼吸努力。四血管脑血管造影的辅助检查证实了脑循环停止。
据我们所知，这是脑死亡测试期间报道的呼吸暂停试验时间最长的病例。排除了已知会导致二氧化碳（PaCO）水平上升延迟的变量。我们怀疑高动力心脏状态导致心脏通气，从而使二氧化碳水平缓慢升高。
