Background: The weaning of critical care patients with acute kidney injury (AKI) from renal replacement therapy (RRT) lacks predictive criteria. The urinary urea excretion index (UUEI) based on the urine urea concentration and diuresis may be a relevant prognostic criterion. The aim of this study was to assess the value of utilising a UUEI-based weaning protocol from a RRT catheter.
Methods: This was a multicentre before-after study including patients with non-obstructive AKI requiring RRT during their intensive care unit (ICU) stay. A before cohort (2013-2015) was compared to an after cohort (2017-2019) in the interval of which a UUEI-based weaning protocol was implemented. In the after cohort, as soon as the UUEI exceeded 1.35 mmol/kg/24 h, physicians were encouraged to stop RRT and withdraw the catheter, whereas in the before cohort the catheter was withdrawn at the physician's discretion. The primary outcome was the number of RRT catheter-free days on day 28 after initiating RRT.
Results: In total, 179 and 130 patients were included in the before and after cohorts, respectively. The median numbers of catheter-free days in the before and after cohorts on day 28 were 13.0 (IQR 0.0-21.0) vs. 16.5 (IQR 4.3-24.0), respectively (p = 0.02). The adjusted rate ratio for the number of catheter-free days over the number of days at risk was 1.11 (95% CI 1.03-1.19; p = 0.006) in favour of the after cohort. Catheters were reinserted to resume RRT in 3 vs. 5 patients in the before and after cohorts, respectively.
Conclusions: These results confirm that a UUEI-based protocol is a safe technique to prompt withdrawal of the RRT catheter in patients with AKI requiring RRT during their ICU stay.
Trial registration: ClinicalTrials.gov NCT03763188.
Keywords: Acute kidney injury; Intensive care unit; Renal replacement therapy; Urinary urea excretion index.
© 2025. The Author(s).