The cardiopulmonary bypass (CPB) procedure has been shown to be a possible cause of postoperative neurological morbidity for various reasons, including: large amounts of gaseous microemboli (GME) reaching the patient and hypoperfusion of the patient due to “stolen” blood flow.This study used a simulated CPB circuit identical to that in a clinical setting to examine three different hollow-fiber membrane oxygenators without intergrated arterial filters - the Capiox RX05, the Quadrox-i neonatal, and the KIDS D100 - to determine their ability to reduce the number of GME delivered to the neonatal patient and their hemodynamic properties in response to varying flow rates, normothermic vs hypothermic conditions, and open vs closed purge line.The circuit was primed with Ringer's Lactate and then human blood with a hematocrit of 30%. Injections of 5cc bolusses of air were injected into the venous line proximal to the venous reservoir over a thirty-second interval. Six injections were done for each oxygenator at each of the eight different experimental conditions for a total of 64 experiments per oxygenator (192 total injections). A flow probe, pressure transducer, and Emboli Detection and Classification (EDAC) quantifier transducer were positioned both upstream and downstream of the oxygenator to measure differences in each parameter. Results demonstrated that the Capiox RX05 is the most effective oxygenator at reducing the number of microemboli that potentially can be delivered to the neonatal patient. In regards to the hemodynamic properties, the Quadrox-i has the most favorable results, with the lowest mean pressure drop and the best energy retention across the oxygenator.