Urinary neutrophil gelatinase-associated lipocalin time course during cardiac surgery

Background: NGAL is one of the most promising AKI biomarkers in cardiac surgery. However, the best timing to dose it and the reference values are still matter of discussion. Aim of the Study: We performed a uNGAL perioperative time course, to better understand its perioperative kinetics and its role in AKI diagnosis. Setting of the Study: San Raffaele University Hospital, cardiac surgery department. Material and Methods: We enrolled in this prospective observational study 19 patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Based on preoperative characteristics, they were divided in low-risk and high-risk patients. uNGAL measurements were collected at pre-defined times before, during, and up to 24 hours after surgery. Statistical Analysis: Data were analysed by use of SAS 1999-2001 program or IBM SPSS Statistics. Results: In low-risk patients, uNGAL had the highest value immediately after general anesthesia induction (basal dosage: uNGAL: 12.20ng×ml ^-1 , IQR 14.00). It later decreased significantly (3.40 ng×ml ^-1 , IQR 4.80; P = 0.006) during CPB, and finally return to its original value 24 hours after surgery. In high-risk patients, uNGAL increased immediately after surgery; it had the highest value on ICU arrival (38,20 ng×ml ^-1 ; IQR 133,10) and remained high for several hours. A difference in uNGAL levels between the two groups was already observed at the end of surgery, but it became statistically significant on ICU arrival (P = 0.002). Conclusion: This study helps to better understand the different kinetics of this new biomarker in low-risk and high-risk cardiac patients.