Time-weighted urine oxygen tension as a predictor of acute kidney injury in patients with sepsis: a preliminary prospective observational study

Background Septic associated acute kidney injury (SA-AKI) is common in the critically ill. Inadequate renal medullary tissue oxygenation has been linked to its pathogenesis. The aim of this preliminary study was to assess the feasibility of intermittent PuO2 monitoring using a blood gas analyzer in sepsis patients; to explore the effectiveness of time-weighted average PuO2 (PuO2TW) for predicting SA-AKI.Methods A total of 76 consecutive adult patients who were admitted to our intensive care unit (ICU) from September 2023 to March 2024 were prospectively recruited. PuO2 was measured with a blood gas analyzer at 0h, 3h, and 6h after ICU admission. PuO2TW was determined by the sum of the mean PuO2 values among consecutive time points multiplied by the period of time between consecutive time points and then dividing by the total time. All patients were followed throughout the ICU stay, and the development of SA-AKI during 48 h was evaluated.Results Approximately 23.68% developed AKI during the ICU stay. PuO2TW was lower in patients who developed AKI. The ROC curve analysis revealed that lower PuO2TW was associated with AKI development at the cutoff of <68 mmHg (area under the curve [AUC] 0.687; p = .008). In the logistic regression models, PuO2TW lower than 68 mmHg was associated with the development of AKI, when adjusted by confounding factors (OR 8.20; p = .002).Conclusions Measurement of PuO2 is feasible by collecting urine from a Foley catheter for analysis in a blood gas machine. 6h PuO2TW had a significant independent predictive value for AKI.