Introduction: The membrane oxygenator in extracorporeal circulation circuits is coated with acrylate-copolymer (ACP) or immobilized heparin (IHP) to enhance hemocompatibility. To evaluate the relative features of both coatings, we compared blood components circulated in the circuits with ACP-and IHP-coated membranes in vitro using whole human blood.
Methods: Whole human blood was heparinized and circulated in two experimental circuits with an ACP-coated reservoir, tubes, and an ACP- or IHP-coated membrane. Platelet (PLT) counts and the amount of total protein (TP), complement component 3 (C3), and complement component 4 (C4) were measured at 0, 8, 16, 24, and 32 h in each experiment (n = 5).
Results: The PLT count at 0-h circulation was lower in the IHP-coated than in the ACP-coated circuits (p = 0.034); however, no significant difference was observed at other time points. Reduction in TP at 8-h and 16-h circulation and in C3 at 32-h circulation was lesser in the ACP-coated than in the IHP-coated circuits (p = 0.004, 0.034, and 0.027, respectively); reduction in TP and C3 at other time points and C4 at each time point was not significantly different. There were significant interactions between coating type and circulation duration in the PLT, TP, and C3 transitions (p = 0.008, 0.020, and 0.043, respectively).
Conclusions: Our findings suggest that ACP-coated membranes can prevent the initial drop in PLT count and C3 consumption over 32 h, whereas IHP-coated membranes could not prevent this drop in extracorporeal circulation. Therefore, ACP-coated membranes are suitable for short- and long-term extracorporeal life support.
Keywords: cardiopulmonary bypass; complement activity; extracorporeal circulation; heparin coating; membrane oxygenator; platelet aggregation; polymer coating.