Objective: Postoperative delirium (POD) is a common complication after major surgery. Our aim was to prove the hypothesis that systemic inflammatory response syndrome (SIRS) contributes to the develop-ment of POD. SIRS is a complex network of mutually interacting processes where one of the terminál tis-sue effectors is COX-2. Design: Prospective open-label study. Setting: Center for Cardiac Surgery and Transplantation. Materials and Methods: 86 consecutive patients all over 65 years of age with coronary artery disease were enrolled. All of them were indicated for open-heart surgery (with or without revascularization). Patients with a past history of postoperative delirium were excluded. The patients were randomized into two groups: treated (N = 40) and controis (N = 46). The treated patients were administered parecoxib (40 mg IV after arrival on the ICU + continuous infusion of 1 mg/kg/day on the day of surgery and the first postoperative day) followed by valdecoxib (2 x 20 mg orally) on the second and third days. Each postoperative day (1-7) the patients were scored for the severity and clinical relevance of POD (0-5).The incidence, duration and severity score of POD were evaluated. Results: No differences in age, comorbidity and perioperative factors were observed between the groups. The duration of POD was significantly shorter in the treated group than in the control group (1.9 ± 0.9 vs. 3.6 ±1.6 days; P = 0.02). The incidence of POD was the samé in both groups. The severity score was lower in the treated group but did not reach statistical significance.The difference in the incidence of postoperative complications was not significant. Conclusion: Systematic administration of COX-2 inhibitors shortened POD duration after cardiac surgery suggesting that COX-2 could contribute to its development. POD ranks among the complications induced by SIRS. Interventions targeted at suppressing SIRS could act as a prevention of POD.

        Key words: postoperative delirium - coxibs - cardiac surgery