Complement activation during and after open-heart surgery is only marginally affected by the choice of fluid for volume replacement

Forty patients undergoing CPB for coronary artery surgery, using a standardized technical setting, were randomized to receive either Ringer's acetate, dextran 70 (Macrodex), polygeline (Haemaccel) or albumin 4% for volume replacement during and after surgery. The choice of fluid did not affect early complement activation (C3 activation products). Higher values of the terminal complement complex (TCC) were found only at the end of the operation in patients receiving polygeline. There were no differences between any two of the four groups during the postoperative course. The use of blood transfusion or autotransfusion and the degree of haemodilution and hypothermia did not affect complement activation. We conclude that complement activation in association with open-heart surgery is only marginally affected by the choice of fluid for volume replacement.

Time for new concepts about measurement of complement activation by cardiopulmonary bypass?

Fifty-one patients admitted for routine coronary bypass operations were randomized to cardiopulmonary bypass with a membrane oxygenator (Capiox) or a bubbler (Polystan or William Harvey). Complement activation was measured using enzyme immunoassays for concentrations of C3 activation products and the terminal complement complex. From 5.8 to 8.1 arbitrary units (AU)/mL (medians), the plasma concentrations of C3 activation products increased by 119.9 AU/mL (Capiox), 124.6 AU/mL (Polystan), and 79.5 AU/mL (William Harvey) to a peak at closure of the sternum (not significant when related to baseline concentrations). The increase in C3 activation products and baseline C3 activation were linearly correlated (R2 = 0.30; p less than 0.0001). From 5.5 to 6.1 AU/mL, the plasma terminal complement complex concentrations increased by 45.2 AU/mL (Capiox), 15.4 AU/mL (Polystan), and 17.4 AU/mL (William Harvey) to a peak before termination of cardiopulmonary bypass. Maximal terminal (C5-C9) activation was significantly higher in the membrane oxygenator group (p less than 0.0001) and showed no relationship to C3 activation. Measurement of C3 activation only gives no information about C5-C9 activation. At present, terminal complement complex quantitation is probably the best index of C5-C9 activation during cardiopulmonary bypass.