Complement activation, cytokines, and adhesion molecules in children undergoing cardiac surgery with or without cardiopulmonary bypass

The effect of cardiopulmonary bypass (CPB) on various blood parameters in c hildren undergoing major cardiovascular surgery was investigated in a prosp ective clinical study. Blood samples of children with CPB (CPB group, n = 1 8) or without CPB (control, n = 12) were collected before, during, and afte r surgery. The concentration of routine laboratory parameters, components o f the complement system (C3, C4, C5, C1 inhibitor, total hemolytic compleme nt, C3d, and C5a), circulating interleukins (IL-6 and IL-8) and soluble adh esion molecules (sICAM-1 and sE-selectin) were determined. In both groups o f patients the serum concentrations of C3, C4, C5, and C1 inhibitor were si gnificantly affected by the treatments (p < 0.001), decreased immediately a fter onset of anesthesia, were minimal during surgery, and increased therea fter. No significant differences in the kinetics of these parameters were d etectable between CPB and control group. In the CPB group the activation of the alternative pathway (increased C3d) was found to be a specific respons e (p = 0.005), but also in the control group C3d and C5a concentration incr eased significantly (p < 0.022), indicating complement activation. None of the effects that would be expected after activation of the complement syste m were specific for the CPB group. In both groups the serum levels of IL-6 increased dramatically during and/or after surgery (p = 0.001), and IL-8 wa s detectable after surgery in 10/12 control patients. The concentration of sICAM-1 and sE-selectin decreased during surgery (p < 0.04) and later did n ot increase above baseline. Our data suggest that increased serum levels of inflammation mediators and increased consumption of complement and adhesio n molecules occur during cardiovascular surgery. Although complement activa tion and ICAM-1 consumption are more pronounced in the CPB patients, none o f these changes occurs exclusively in the CPB group. We conclude, therefore , that these changes are the combined effect of anesthesia, surgical trauma , and endothelial lesions. Additional, undefined CPB-induced reactions may also contribute the postoperative morbidity.