Comparison of mini-cardiopulmonary bypass system with air-purge device to conventional bypass system

Background. Although mini-cardiopulmonary bypass systems reduce inflammation, hemodilution, and transfusion requirements, the problem of air entrainment and embolization into the system has limited its use. Newer systems incorporate an air purge to address this problem. We compared the benefits and possible risks in using the newer mini-cardiopulmonary bypass system with those for conventional cardiopulmonary bypass. Methods. Data of 60 patients who underwent cardiac surgery with a newer mini-cardiopulmonary bypass system incorporating an air purge from August 2005 to July 2006 (group A) were retrospectively collected and compared with that of 60 matched patients who underwent cardiac surgery with conventional cardiopulmonary bypass during the same period (group B). Matching criteria were prebypass hematocrit, body surface area, age, and surgical procedure. Results. Demographic and background data were similar for both groups. There were no detectable episodes of air embolism. Patients in group A had higher initial and nadir hematocrits during cardiopulmonary bypass and received fewer transfusions. However, postoperative blood loss and transfusion requirements were similar in both groups. Episodes of low indexed flows during cardiopulmonary bypass commonly occurred in group A, and this was associated with a greater than 50% decrease in urine output and lower mixed venous oxygen saturations (58% +/- 6% versus 68% +/- 5%) as compared with group B. There were no differences in clinical outcomes. Conclusions. The newer mini-cardiopulmonary bypass system addressed the problem of air embolization. It preserved hematocrit and reduced transfusion during cardiopulmonary bypass, but did not improve outcomes postoperatively. It is unclear whether these benefits outweigh the potential risk of hypoperfusion associated with its use.