Potential impact of oxygenators with venous air trap on air embolism in veno-arterial Extracorporeal Life Support

BACKGROUND: Air embolism is a potentially fatal but underrecognized complication in Extracorporeal Life Support (ECLS). Oxygenators containing venous air traps have been developed to minimize the risk of air embolism in daily care. OBJECTIVE: We reproduced air embolism as occurring via a central venous catheter in an experimental setting to test the potential of oxygenators with and without venous bubble trap (VBT) to withhold air. METHODS: An in vitro ECLS circuit was created and a central venous catheter with a 3-way stopcock and a perforated male luer cap was inserted into the inflow line. Three different oxygenators with and without VBT and their capability to withhold air were examined. After 60 seconds of stable ECLS flow, the stopcock was opened towards the atmosphere for 3 minutes. Afterwards, air accumulation within the oxygenator was determined. RESULTS: Comparison of the total air entrapment showed a significant superiority of the oxygenators with VBT (p < 0.001). All oxygenators were able to partly withhold macro air boli, however, the capacity of oxygenators with VBT was higher. Passing through the oxygenator resulted in a reduction of microbubbles in all cases. CONCLUSIONS: Macro air emboli can be substantially reduced by usage of oxygenators that contain a VBT, whereas the capability to withhold microbubbles to a vast extent seems to depend on the intrinsic oxygenator's membrane.