Is cardiopulmonary bypass (CPB) a trigger for systemic inflammatory response syndrome (SIRS) in cardiac surgery?

Objectives: In a small group of patients SIRS can be the cause of fatal clinical outcome after cardiac surgery. As many authors accept CPB as a main reason for a SIRS, the incidence of „off-pump-techniques“ CPB rises. Material and Methods: We performed a prospective study using standardized operative procedures with CPB. A group A (no SIRS, n=20) was compared to a group B (postoperative SIRS, n=12). At 6 time points, beginning before and ending 2 days after surgery, we measured plasma levels of blood lactate, endothelin 1 (ET1), ICAM-1 (CD54), ICAM-3 (CD50), VCAM-1 (CD106), and ELAM-1 (E-selectin) with ELISA technique. Results: In the control group (CAD-patients), all patients had a uneventful postoperative course. In the SIRS-group 7 patients (58%) died. We found significantly higher preoperative levels of ET1 (2.5±0.3 vs. 1.2±0.4 pg/ml), ICAM-1 (537±24 vs. 387±22 ng/ml), ICAM-3 (270±15 vs. 202±20 ng/ml), and ELAM-1 (60±11 vs. 37±9 ng/ml) in SIRS patients. After starting CPB we measured a significant increase of blood lactate levels in this group (3.7±0.3 vs. 2.2±0.2mg/dl). Conclusions: Since adequate therapies are missing, the preoperative identification of „risk-patients“ is one of the most important goals in cardiac surgery. With the results of this study, we can conclude that a preoperative activation of the endothelium in patients with coronary artery disease represents a main risk factor for an inflammatory complication. A general tissue hypoxia with elevated blood lactate levels immediately after start of CPB in these patients may be the next step in the ongoing cascade of SIRS.