Continuous Urine Output-Based Alert Identifies Cardiac Surgery–associated Acute Kidney Injury Earlier Than Serum Creatinine: A Prospective and Retrospective Observational Study

Abstract

Objective(s)Acute kidney injury (AKI) is defined and staged by reduced urine output (UO) and increased serum creatinine (SCr). UO is typically measured manually and documented in the electronic health record, making early and reliable detection of oliguria-based AKI and electronic data extraction challenging. We investigated the diagnostic performance of continuous UO, enabled by active drain line clearance, based alerts (Accuryn AKI Alert), compared to AKI stage 2 SCr criteria and their association to length of stay (LOS), need for continuous renal replacement therapy (CRRT), and 30-day mortality. DesignProspective and retrospective observational study. SettingNine tertiary centers. ParticipantsCardiac surgery patients. InterventionsNone. Measurements and Main Results522 patients were analyzed. AKI stages 1, 2, and 3 were diagnosed in 32.18%, 30.46%, and 3.64% of patients based on UO compared to 33.72%, 4.60%, and 3.26% of patients using SCr, respectively. Continuous UO-based alerts diagnosed stage ≥1 AKI 33.6 (IQR= [15.43, 95.68]) hours before stage ≥2 identified by SCr. A SCr-based diagnosis of AKI stage ≥2 has been designated a Hospital Harm by the Centers for Medicare & Medicaid Services. Using this criterion as a benchmark, AKI alerts had a discriminative power of 0.78. AKI Alert stage 1 was significantly associated with increased ICU and hospital LOS and CRRT, and stage ≥2 alert with mortality. ConclusionsAKI Alert based on continuous UO, enabled by active drain line clearance, detected AKI stages 1 and 2 before SCr. Early AKI detection allows for early kidney optimization, potentially improving patient outcomes.