Carbogen for Apnea Testing During the Brain Death Declaration Process in Subjects on Extracorporeal Membrane Oxygenation

BACKGROUND: The use of extracorporeal membrane oxygenation (ECMO) in adult patients continues to increase. Suspicion of brain death while on ECMO creates a conundrum. The American Academy of Neurology states that apnea testing is a critical component of the process to declare brain death. However, there is a paucity of literature on apnea testing for confirmation of brain death in patients on venoarterial ECMO and venovenous ECMO. Traditional apnea testing does not consider ECMO physiology or de-recruitment of the lungs in this subset of critically ill patients. Complications with traditional apnea testing include hemodynamic instability that may lead to cardiac arrest and death.

METHODS: We conducted a retrospective review of apnea tests using the carbogen method performed for brain death determination on 5 subjects on ECMO. A positive apnea test was used in confirmation of brain death in all 5 subjects on either venovenous ECMO (n = 2) or venoarterial ECMO (n = 3) while remaining on mechanical ventilation. A formula was used to calculate the subject's target value for CO₂ production and completion of the apnea test.

RESULTS: In all 5 cases, the carbogen method resulted in 100% accuracy of the targeted CO₂ goal, and apnea testing was confirmed with no adverse events.

CONCLUSION: In 5 subjects on ECMO, the carbogen method for apnea testing as part of the process to declare brain death was accurate in predicting the end point of the apnea test. With the increased use of ECMO in adults and the ongoing need for organs, methods to confirm brain death with apnea testing while on ECMO should be further studied.