Vasopressinase Activity: A Potential Early Biomarker for Detecting Cardiopulmonary Bypass-Associated Acute Kidney Injury?

Background Acute kidney injury (AKI) is a common and serious complication of surgeries that include cardiopulmonary bypass (CPB). Currently, increases in serum creatinine levels are used to diagnose AKI, but this change may be slow to detect. Animal studies pertaining to renal hypoxia suggest a correlation between vasopressinase activity and AKI. The objective of this study is to determine if vasopressinase activity can be used as an early biomarker for renal hypoxia and CPB-associated AKI. This could potentially help improve the diagnosis and subsequent treatment of the condition. Materials and Methods We conducted a single-center, prospective observational study which analyzed serum vasopressinase activity and creatinine levels at seven time points from 31 patients undergoing CPB. We also measured urine vasopressinase activity in 19 of the 31 patients at five of the time points. Results Results show that serum and urine vasopressinase activity peak at the time of arrival to the ICU for patients undergoing CPB. This increase occurred earlier than the increase in creatinine, which generally occurred on postoperative day 2. In the five patients who were diagnosed with AKI, vasopressinase activity peaked 30 minutes into CPB while creatinine peaked on postoperative day 2. Conclusion Our findings suggest that vasopressinase might be a potential early biomarker for AKI. Further studies with other AKI biomarkers are required to determine if the vasopressinase response can be directly attributed to the presence of AKI.