RESUMO
OBJECTIVES: The objectives of this study were to quantify the immunosuppressive effects of cardiopulmonary bypass (CPB) and to identify mechanisms responsible for the postoperative immunosuppression of patients undergoing cardiac surgery. DESIGN: A prospective study from 20 consecutive patients. SETTING: The same team operated on all patients in a major teaching hospital, and the immunologic tests were performed in the hospital's hematology laboratory. PARTICIPANTS: Twenty patients were studied who had consented to participate in the study. INTERVENTIONS: All patients underwent valve replacement under general anesthesia. MEASUREMENT AND MAIN RESULTS: The changes in the white blood cell count (WBC), in the B, T, T4, T8 lymphocytes, the concentrations of C-reactive protein (CRP), a1-antitrypsin (A1AT), a2-macroglobulin (A2MG), C3, C4 immunoglobulin A (IgA), IgM, IgG, Kappa (K), and lambda (L) chains were studied. The postoperative immune response was expressed with (1) increased mean axillary temperature (37.5 degrees +/- 0.62 degrees) in the first postoperative 24 hours; (2) increase of WBC (p < 0.001) and T8 (p < 0.01); (3) reduction of C3 (p = 0.01) and A2MG (p < 0.01); (4) reduction of IgA (p < 0.001) and IgG, K, L chains (p < 0.01); and (5) reduction of T (p < 0.01) and T4 (p < 0.01). In the first 24 hours postoperatively, B cells were increased (81%) together with CRP (p < 0.01) and A1AT. CONCLUSIONS: The observed immune alterations were mostly of no immunologic origin and were related to hemodilution and inflammation together with an immunosuppressive effect of trauma and stress.
