Changes in leukocyte counts and soluble ICAMI and E-selectin during cardioputmonary bypass in children

Abstract

A consequence of cardiopulmonary bypass (CPB) in young children is postoperative capillary leak and associated pulmonary dysfunction. Neutrophils sequester in itic lungs during CPU and may contribute to functional endothelial damage. Endothelial adhesion molecules E-selectin and ICAMI mediate sequential steps in adhesion by binding to leukocyte ligands. Circulating forms of these proteins have recently been identified. We therefore studied changes in the plasma concentrations of soluble E-selectin and soluble ICAMI using fixed phase immunoassays, and associated leukocyte counts in 10 pediatric patients undergoing CPB for corrective cardiac surgery. Preoperative concentrations of soluble E-selectin and soluble ICAM-1 consistently fell during CPB from 89±27ng/ml (mean ± 2SE) and 218±70ng/ml respectively, to 39±12ng/ml and 84 ± 28ng/ml respectively at the beginning of maximum hypothermia during CPB, The haemodilution that occurred during CPB largely explained this fall, but not a more marked decrease in while cell counts that also occurred over this period (6.66±1.23 to 1.73±1.73×109/l) which may reflect increased leukocyte sequestration. By 24 hours postoperatively, levels of both soluble adhesion molecules approached preoperative concentrations, as did lymphocyte counts. In marked contrast neutrophil counts rose appreciably at the end of CPB and during llie immediate postoperative period and remained at these elevated levels 24 hours later. Major consistent elungcs in circulating leukocyte numbers which occur early in CPB may reflect changes in adhesion to endothelium and consequent sequestration. Alterations in the levels of soluble adhesion proteins may influence these processes.