Apnea Testing for the Determination of Brain Death in Patients Supported by Extracorporeal Membrane Oxygenation

Abstract

The neurological criteria for brain death include coma, absent brain stem reflexes, and apnea. For patients on extracorporeal membrane oxygenation (ECMO), routine apnea testing is not possible because gas exchange occurs entirely through the membrane oxygenator. We describe the protocol we used to perform the apnea test and declare brain death in a patient on ECMO and review the literature of brain death testing in patients on ECMO. A 39-year-old female presented with cardiogenic shock followed by pulseless electrical activity (PEA) and eventually started on veno-arterial (VA) ECMO. Neurology was consulted for prognostication. Initial exam 48 hours after arrest showed absent brain stem reflexes. Another neurological exam 72 hours after arrest was compatible with brain death, so apnea test was performed. The apnea test involved preoxygenation, then she was disconnected from ventilator and the gas sweep rate decreased to 1 L/minute while maintaining the same blood flow rate. At 10 minutes, the PCO 2 level needed to declare brain death was achieved. With increasing use of ECMO to support critically ill patients, physicians should become familiar with the challenges this technology has created when testing for apnea in the determination of brain death. In this case report, we showed that apnea testing can be done in patients on ECMO without the need for ancillary testing. The mainstay of performing apnea testing on these patients is decreasing the gas sweep rate to 0.5 - 1 L/minute while maintaining the same blood flow rate. J Neurol Res. 2016;6(1):28-34 doi: http://dx.doi.org/10.14740/jnr376w