The haemocompatibility of five different bubble oxygenators (Polystan venotherm, Harvey H-1700, Bentley BIO-10, Gambro 10 and Shiley S-100A HED) and one membrane oxygenator (Cobe CML) have been evaluated during standardized clinical perfusion for open-heart surgery in 48 adult patients. Control of arterial PO2 and PCO2 was an important feature of the evaluation protocol. Over the period of cardiopulmonary bypass (CPB) there was a marked difference in the mean percentage reduction in platelet count in the different oxygenator groups. Only 1% reduction in platelet count occurred with the Cobe CML membrane oxygenator group compared with, in the bubble oxygenator groups, 7% for the Gambro 10, 16% for the Harvey H-1700, 19% for the Shiley S-100A HED, 24% for the Bentley BIO-10 and 31% for the Polystan venotherm. The post bypass platelet count was significantly lower than the prebypass value in all oxygenator groups ( p < 0.05) except the Cobe CML and Gambro 10. The two oxygenator groups with the largest percentage reduction in platelet count (Polystan venotherm and Bentley BIO-1 0) demonstrated a significant reduction ( p < 0.05) in platelet aggregation over the period of bypass. Platelet depletion in the Harvey H-1700. Shiley S-100A HED, Bentley BIO-10 and Polystan venotherm oxygenators was associated with a significant fall ( p < 0.05) in mean platelet volume during the first 35 minutes of CPB due to the removal from the circulation of large, young, functionally more active platelets. Erythrocyte damage was minimal in all oxygenator groups and only a minor degree of leucopenia could be demonstrated during the first five minutes of CPB. Cardiotomy suction was not associated with significant changes in platelet numbers or platelet aggregation. When selecting the oxygenator for use in patients undergoing open-heart surgery, gas transfer characteristics and GME production together with the superior preservation of platelet numbers and function in the membrane oxygenator group and variable degree of platelet depletion and reduction in platelet aggregability demonstrated in the five bubble oxygenator groups, must be taken into account.
