Effect of Oxygenator Size on Air Removal Characteristics: A Clinical Evaluation

During cardiopulmonary bypass (CPB), gaseous microemboli (GME) are released into the patients' arterial bloodstream. Gaseous microemboli may contribute to the adverse outcome after cardiac surgery. Recently, two oxygenator models with or without integrated arterial filter (IAF) were designed and only differ in size, leading to a change of 20% in surface area of the hollow fibers and 25% in blood velocities. The aim of this study was to assess the air removal characteristics of the inspire oxygenators with or without IAF. Sixty-eight patients were randomly assigned to four different groups: optimized adult and full adult and an additional IAF. Gaseous microemboli reduction rates were measured with a bubble counter. The number of GME reduction rates showed no differences. However, both models reduced significantly less volume of GME (optimized adult: 40.6% and full adult: 50.3%) compared with both models with IAF (88.7% and 88.5%, respectively). No significant differences of reduction rates were found between both devices without IAF and also not between both models with IAF. In conclusion, the larger inspire oxygenator tends to remove more GME. No effect from size of oxygenator device with integrated screen filter on GME reduction was observed. The inspire oxygenators with IAF may be considered as an adequate GME filter.