Predictive value of IL-18 and SC5b-9 for neurocognitive dysfunction after cardiopulmonary bypass

Background. Neurological injury after cardiopulmonary bypass (CPB) continues to be a major problem after cardiac surgery. The aim of this study was to investigate the predictive value of Interleukin-18 (IL-18) and SC5b-9 as biochemical markers of neurocognitive dysfunction after cardiac surgery. Methods. A total of 30 patients undergoing elective cardiac surgery using CPB were recruited. Blood samples were obtained for IL-18 and SC5b-9 concentrations before induction, 24, 48, 72, 96 and 120 h post-CPB and 6 weeks after operation. In addition, patients underwent a standard battery of neuropsychometric tests before operation and at day 5 and 6 weeks after operation. Results. Serum concentration of IL-18, but not SCSb-9, was significantly different between patients with and without neurocognitive dysfunction; serum IL-18 concentration significantly increased in patients with neurocognitive dysfunction (P=0.018). Neurological outcome was significantly dependent on peak difference in IL-18 concentration at day 5 (P=0.033), but not on peak difference in SC5b-9 concentration (P=0.16). Eight patients had neurocognitive dysfunction at day 5 and three had neurocognitive dysfunction at 6 weeks. In a very small number of patients, no significant association was demonstrated between IL-18 or SC5b-9 concentrations and neurocognitive dysfunction at 6 weeks. Conclusions. IL-18 has the potential as a useful marker of neurological dysfunction, requiring further investigation.