Postoperative Morbidity Following Red Cell Deformability Changes During Cardiopulmonary Bypass Using Bubble and Membrane Oxygenators

Abstract

The preoperative blood cell trauma and postoperative morbidity were com pared in a prospective randomized study in two groups of patients undergoing cardiac surgery with extracorporeal circulation (ECC). One group was oxygen ated during ECC with a membrane oxygenator (MO) and the other with a bub ble oxygenator (BO). Red cell trauma was ascertained by a standard microfiltration technique that expressed the rheologic properties of standard ized red cell suspensions. The filtrability of the cell suspension was significantly reduced during ECC for both membrane (MO) and bubble (BO) oxygenators. However, the bubble type proved to be more traumatic, and the difference was statistically signifi cant after thirty minutes of ECC. The filtrability was reduced by 20% in the MO group and by 35% in the BO group at the end of ECC (p < 0.01). A significantly higher frequency of postoperative bleeding (p < 0.05), blood transfusion (p < 0.05), and arrhythmias was found in the BO group (p < 0.01). This study demonstrates that the microrheology of red blood cells is better preserved with the membrane oxygenator, which is associated with a smoother postoperative course, owing probably to a better preserved microcirculation. The membrane oxygenator can be recommended even for short perfusions and routine procedures requiring cardiopulmonary bypass (CPB) and should be used whenever possible.