[Cellular injury associated with extracorporeal circulation]

Circulation of blood extracorporeally through plastic tubing causes severe shear stresses to blood cells and activates several regulatory cascades. These various pathways include the cytokine cascades, complement and coagulation. Interleukine-1, -6, -8, tumor necrosis factor-alpha have been implicated. Among various mediators of tissue injury released by activated neutrophils, elastase and metalloproteinases have been considered to be relevant in postoperative organ dysfunction in cardiac operations. Endothelial cells are extremely sensitive to insults that occur during cardiopulmonary bypass (CPB). These insults lead to disruption of barrier function and leukocyte adhesion. Immunoglobulins such as ICAM-1 and VCAM-1 are expressed on endothelium cells and act as ligands for integrins. It is also important to remember that during cardiac operations, the interest on the metabolism of in free radicals has focused on the heart and the lungs because they are exposed to ischemia and subsequent reperfusion. Increased production of free radicals during CPB is associated with myocardial and pulmonary dysfunctions. Now it is well recognized that the whole body inflammatory response induced by CPB is mainly responsible for postoperative organ dysfunctions.