Membrane and bubble oxygenator: a clinical comparison in patients undergoing aortocoronary bypass procedures

Forty patients undergoing aortocoronary bypass procedures were randomyl allocated to a bubble oxygenator group (20 patients) and a membrane oxygenator group (20 patients). Blood chemistry, hematology and hemodynamics before, during and after cardiopulmonary bypass were used to compare the two oxygenators. There was no mortality and no serious complications in both groups. A higher hemolysis, with significantly higher levels of lactic dehydrogenase and free plasma hemoglobin and a more pronounced reduction in platelet count were found in the patients perfused with the bubble oxygenator. These differences persisted for 24 hours after the operation; 48 hours after surgery no significant differences between the two groups could be detected. Postoperative blood loss, intra- and postoperative hemodynamics and pulmonary gas exchange were equal in both groups. These results show, that the routine use of membrane oxygenators brings only minor benefits; therefore it may be specially reserved for extended open-heart procedures and for operations in high risk patients.