Inflammatory response of neutrophil granulocytes and monocytes after cardiopulmonary bypass in pediatric cardiac surgery

Objective: To determine whether the activation state of polymorphonuclear neutrophils (PMNs) and monocytes contributes to the inflammatory response after cardiopulmonary bypass (CPB) in pediatric cardiac surgery. Design: Observational prospective clinical study. Setting: Pediatric intensive care unit of a university hospital. Patients: Twenty pediatric patients before and after open heart surgery with CPB. Measurements: Cell counts of circulating PMNs and monocytes as well as phenotypic and functional analysis of these cells, and plasma levels of myeloperoxidase. Results: Levels of myeloperoxidase (a marker of PMN degranulation) were significantly elevated after CPB (2.9 +/- 1.6 ng/ml before CPB versus 13.7 +/- 6.5 ng/ml after CPB, p=0.0001). However, PMN function, as measured by surface expression of CD11b/CD18 and phagocytic respiratory burst, was reduced. In contrast, the phagocytic respiratory burst of circulating monocytes was increased in some patients and there was a correlation with the increase of monocyte cell count after CPB (r=0.63, p=0.015). Conclusions: After the end of CPB, there was an ongoing inflammatory process. In particular, there was an activation of monocytes after the end of CPB.