The impact of urine flow on urine oxygen partial pressure monitoring during cardiac surgery

Purpose Urine oxygen partial pressure (PuO 2 ) may be useful for assessing acute kidney injury (AKI) risk. The primary purpose of this study was to quantify the ability of a novel urinary oxygen monitoring system to make real-time PuO 2 measurements intraoperatively which depends on adequate urine flow. We hypothesized that PuO 2 data could be acquired with enough temporal resolution to provide real-time information in both AKI and non-AKI patients. Methods PuO 2 and urine flow were analyzed in 86 cardiac surgery patients. PuO 2 data associated with low ( 70% of their data were discarded during the respective periods, i.e., during cardiopulmonary bypass (CPB), before CPB (pre-CPB), and after CPB (post-CPB). The length of intervals of discarded data were recorded for each patient. The median length of intervals of discarded data were compared between AKI and non-AKI patients and between surgical periods. Results There were more valid PuO 2 data in CPB and post-CPB periods compared to the pre-CPB period (81% and 90% vs. 31% of patients included, respectively; p