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

PURPOSE

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

METHODS

PuO and urine flow were analyzed in 86 cardiac surgery patients. PuO 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 PuO 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

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

GOV IDENTIFIER

NCT03335865, First Posted Date: Nov. 8th, 2017.