Use of urinary PO2 for early detection of renal dysfunction in cardiac surgical patients

Background: Medullary hypoxia is a critical initiating event in the development of multiple forms of acute kidney injury (AKI), and the urinary PO2 provides an index of medullary oxygenation. This biomarker has the potential to aid in the management of patients at risk of AKI and, so, to possibly prevent development of AKI. Objective: To evaluate the effect of cardiopulmonary bypass (CPB) on urine oxygen tension (PO2) and determine whether perioperative PO2 can predict postoperative renal dysfunction in patients undergoing cardiac surgery. Materials and Methods: This prospective, observational study has enrolled a total of 63 patients who were undergoing on-pump cardiac surgery. On the basis of the AKI guideline, the patients were distributed into two groups. Group A patients did not develop AKI (n = 45), and the remaining patients developed AKI: group B (n = 12). Preoperative renal data and intraoperative and postoperative data were collected. Result: Urine PO2 data were recorded for 63 patients from blood gas analyzer. Prebypass and postbypass urine PO2 was similar up to 24-h postoperative in all patients. Even in patients who develop AKI, we did not find any difference in urine PO2 prebypass and postbypass. Conclusion: These results suggest the possibility of PO2 detecting an early stage of renal dysfunction in cardiac surgery although further studies will be required to substantiate it.