A Protocol that Mandates Postoxygenator and Arterial Blood Gases to Confirm Brain Death on Venoarterial Extracorporeal Membrane Oxygenation

The apnea test (AT) during clinical brain death (BD) testing does not account for different arterial gas tensions on veno-arterial extracorporeal membrane oxygenation (V-A ECMO). We aimed to develop a protocol and now report our experience with three patients. The protocol was developed and implemented in 2015 at a quaternary center in Australia, measures both right radial and postoxygenator carbon dioxide (CO2) and oxygen (O2) gas tensions during the AT, incorporates regular gas sampling and a gradual reduction in fresh gas flow to ensure patient oxygenation. Patient 1 remained apneic despite both right radial and postoxygenator CO2 gas tensions >60 mmHg. Patient 2, despite having CO2 levels in a right radial arterial sample high enough to diagnose BD, postoxygenator CO2 remained <60 mmHg. Patient 2 did not breathe but radiological tests confirmed BD. Patient 3 showed respiratory effort but only once CO2 levels rose high enough in both right radial and postoxygenator samples. No patient was hypoxic during the AT. Performance of a reliable AT on V-A ECMO requires measurement of both right radial and postoxygenator blood gases. A protocol, which measures both blood gas values, is feasible to implement, while being both safe and easy to perform.