RESUMO
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.