Abstract 341: Urine Output and Blood Urea Nitrogen Predict Mortality After Out-of-Hospital Cardiac Arrest

Abstract

Introduction: Renal dysfunction, as defined by elevated serum creatinine, is associated with decreased survival among patients resuscitated after out-of-hospital cardiac arrest (OHCA). Less is known about other measures of renal function and outcomes after OHCA. Hypothesis: BUN and urine output will predict mortality after OHCA. Methods: Retrospective single-center cohort study of 276 adult OHCA patients treated with targeted temperature management after OHCA between December 2005 and September 2016. Fluid balance and urine output were recorded for the first 6, 12 and 24 hours. Initial laboratory values were determined from electronic records. Hospital survivors and non-survivors were compared using the Wilcoxon test, and multivariate analysis was performed to determine predictors of hospital death. Results: Mean age was 63±12 years, and 204 (73%) were male; shockable rhythm occurred in 241 (87%). Inpatient death occurred in 111 (40%). Hospital survivors had lower initial BUN (13 vs. 20 mg/dL) and creatinine (1.1 vs. 1.5 mg/dL); all p <.001. Hospital survivors had higher (p <.001) urine output during the first 6 hours (1,091 vs. 559 ml), 12 hours (1,583 vs. 843 ml), and 24 hours (2,215 vs. 1,294 ml). Higher initial BUN (OR 1.12, 95% CI 1.07-1.18) and creatinine (OR 3.036, 95% CI 1.65-5.59) predicted hospital mortality; all p <.001. Urine output during the first 24 hours was associated with hospital mortality (OR 0.57 per each 1 L, 95% CI 0.45-0.72, p <.001; AUROC 0.73, optimal cut-off 1 L). Patients with 24-hour urine output <1 L were at increased risk of hospital death (66.3% vs. 26.0%, unadjusted OR 5.61, 95% CI 3.27-9.63, p <.001). Initial BUN (adjusted OR 1.09, 95% CI 1.01-1.16, p=.02) and urine output during the first 24 hours (adjusted OR 0.71 per each 1 L; 95% CI 0.52-0.97, p=.03) remained predictive of hospital mortality after adjustment for patient characteristics and illness severity. Conclusions: Lower 24-hour urine output and higher initial BUN were associated with higher hospital mortality among patients resuscitated from OHCA, even after adjustment for illness severity. Serum creatinine was not a significant predictor of mortality. This emphasizes the importance of low urine output as a prognostic marker and therapeutic target after OHCA.