Purpose

Urine oxygen partial pressure (PuO₂) 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 PuO₂ measurements intraoperatively which depends on adequate urine flow. We hypothesized that PuO₂ data could be acquired with enough temporal resolution to provide real-time information in both AKI and non-AKI patients.

Methods

PuO₂ and urine flow were analyzed in 86 cardiac surgery patients. PuO₂ data associated with low (< 0.5 ml/kg/hr) or retrograde urine flow were discarded. Patients were excluded if > 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 PuO₂ data in CPB and post-CPB periods compared to the pre-CPB period (81% and 90% vs. 31% of patients included, respectively; p < 0.001 and p < 0.001). Most intervals of discarded data were < 3 minutes during CPB (96%) and post-CPB (98%). The median length was < 25 s during all periods and there was no significant difference in the group median length of discarded data intervals for AKI and non-AKI patients.

Conclusions

PuO₂ measurements were acquired with enough temporal resolution to demonstrate real-time PuO₂ monitoring during CPB and the post-CPB period.