Abstract 209: The Relationship Between the Ratio of Urine Osmolality to Serum Osmolality and Neurological Outcome of Out-of-Hospital Cardiac Arrest Patients

Abstract

Background: Progressive hypoxic brain injury after cardiac arrest can affect serum osmolality (SOsm) and urine osmolality (UOsm) in out-of-hospital cardiac arrest (OHCA) patients. This study aimed to examine the association between the ratios of UOsm to SOsm (USRs) within 3 days after return of spontaneous circulation (ROSC) and neurological outcomes in OHCA patients. Methods: The present study was prospective observational study and included OHCA patients with targeted temperature management (TTM) at Chonnam National University Hospital in Gwangju, Korea, between January 2016 and December 2022. We collected SOsm and UOsm at admission and at 24 h, 48 h, and 72 h after ROSC. We assessed the predictive performance of USRs to determine neurological outcome at discharge. Results: A total of 319 patients were included. UOsm levels and USRs at admission and 24 h, 48 h, and 72 h after ROSC in patients with poor outcome were lower than those in patients with good outcome. In multivariable analysis, the USRs at 24 h (odd ratio [OR], 0.363; 95% confidence interval [CI], 0.221-0.594), 48 h (OR, 0.451; 95% CI, 0.268-0.761), and 72 h (OR, 0.559; 95% CI, 0.357-0.875) after ROSC were independently associated with poor neurological outcome at discharge. The area under the receiver operating characteristic curves of USRs at admission and 24 h, 48 h, and 72 h after ROSC for predicting neurological outcome at discharge were 0.615 (95% CI, 0.559-0.669), 0.711 (95% CI, 0.658-0.760), 0.724 (95% CI, 0.671-0.772), and 0.751 (95% CI, 0.699-0.797). Conclusions: The USRs within 3 days of ROSC were associated with poor neurologic outcome at discharge in OHCA patients.