Methods: Thirty consecutive patients (22 males, 8 females; mean age 62.4±9.0 years; range 49 to 78 years) who underwent openheart surgery were enrolled in this prospective study. Serum IL-18 concentrations were analyzed prior to induction of anesthesia, at weaning from cardiopulmonary bypass (CPB) and two hours after weaning from CPB. Serum creatinine levels were analyzed in the postoperative first, second, and third days. Acute kidney injury was defined as creatinine levels exceeding 50% of the basal value or exceeding the basal value by 0.3 mg/dl at 48 hours postoperatively. The patients were classified into two groups including AKI (n=12) and non-AKI (n=18). Serum IL-18 levels were compared between the groups.

Results: Twelve patients (40%) developed AKI. The diagnosis was able to be made using the serum creatinine levels at 24 to 48 hours postoperatively. Although IL-18 concentrations at weaning from CPB decreased slightly in the AKI group, the decrease in the non- AKI presenting group was higher. Using univariate analyses, IL-18 concentrations at two hours after weaning from CPB were found to be related to AKI (p=0.031). The difference in serum IL-18 concentrations between the preoperative period and two hours after weaning from CPB were found to be statistically significant (p=0.017). According to the Receiver operating characteristic curve analysis, the threshold value for AKI prediction of serum IL-18 concentrations at two hours after weaning from CPB was 353.7 pg/ml with a sensitivity of 58.3% and a specificity of 83.3% (AUC=0.736).

Conclusion: Serum IL-18 concentration may be used as a biochemical indicator for early detection of acute kidney injury following open heart surgery.