Effect of Serum Precoat on Complement Activation in Membrane Oxygenators: An In Vitro Study

-----------------Previous studies have shown that extracorporeal circulation devices can activate the complement cascade via the alternative pathway. Anaphylatoxins (C3a and C5a) generated by complement activation may lead to pulmonary leukocyte sequestration, pulmonary edema, granulocytopenia and microvascular lung damage. This is of particular concern in patients on cardiopulmonary bypass. The purpose of this study was to examine the impact on complement activation of precoating membrane oxygenators with serum. A pool of recalcified human serum was prepared from fresh frozen plasma stored in citrate phosphate dextrose. SciMed membrane oxygenators (N=4) were primed with 200 ml aliquots of pooled serum which were recirculated through the oxygenators for 180 minutes at 37° C. The primary recirculation serum C3a levels (mean ± SD) measured by radioimmunoassay techniques at 0, 60, 120, and 180 minutes were 122.25 ± 26.22, 430.25 ± 164.39, 456.0 ± 154.16 and 577.5 ± 163.07 ng/ml respectively. Each oxygenator was then flushed with saline and reprimed with a fresh 200 ml aliquot of pooled serum which was recirculated for 180 minutes at 37° C. The secondary recirculation serum C3a levels (mean ± SD) measured at 0, 60, 120, and 180 minutes were 130.75 ± 15.67, 213.25 ± 58.24, 283.75 ± 27.24 and 301.75 ± 19.18 ng/ml respectively. Serum C3a levels were higher in the primary serum than the secondary serum in all oxygenators. These results suggest that preconditioning the oxygenator may be a way to moderate complement activation during cardiopulmonary bypass. Introduction-----------------It is now widely accepted that contact between human blood and foreign surfaces such as silicon, nylon, or cellulose during extracorporeal circulation activates the alternative pathway of the complement cascade ( 1-7). Chenoweth and colleagues demonstrated that the complement cascade is activated by the initiation of cardiopulmonary bypass and that complement production continues through the duration of the procedure (8). The complement cascade consists of a set of circulating serum Address correspondence to: Patrick F. Plunkett, Ed.D., 234 Mugar Life Science Building, Northeastern University, Boston,