Exploratory Analysis of Urine PO2 Peri-Procedural Kinetics and CI-AKI Prognostic Abilities in Patients Undergoing PCI

Novel contrast-induced acute kidney injury (CI-AKI) biomarkers are needed to detect earlier and with greater precision the pathophysiological changes in the renal medulla associated with kidney damage. We prospectively assessed the kinetics of urine oxygen tension (PO 2 ) in control healthy individuals and its prognostic ability for CI-AKI in patients undergoing percutaneous coronary intervention (PCI). We enrolled 202 consecutive patients (78% men, mean age 66 ± 10 years) treated with elective or urgent PCI. PO 2 was measured using a point-of-care (POC) standard blood gas analyzer at 3 time points (baseline, post-within 3 hours-PCI, and at 24 hours post-PCI) in urine samples. CI-AKI was defined as an increase of ≥25% or ≥0.5 mg/dl in pre-PCI serum creatinine at 48 hours post-PCI. Between baseline and post-PCI measurements, patients without CI-AKI showed a decrease of -37 (36) mm Hg in PO 2 urine levels, whereas patients with CI-AKI showed a decrease of only -23 (38) mm Hg. ( P = 0.014). Using receiver operating characteristic curve analysis, percentage change in urine PO 2 immediately after PCI relative to baseline levels significantly predicted CI-AKI (area under the curve 0.804; 95% confidence interval, 0.717-0.892). A significant drop in urine PO 2 appears as a normal response of the kidney medulla to an acute insult (contrast media) immediately post-PCI with recovery to baseline levels 24 hours later. The absence or attenuation of this drop in urine PO 2 could predict CI-AKI earlier and more precisely.