614: URINE BIOMARKERS, ACUTE KIDNEY INJURY, AND FLUID OVERLOAD IN INFANTS AFTER PEDIATRIC HEART SURGERY

Abstract

Introduction: Acute kidney injury (AKI) and fluid overload (FO) are common in infants after heart surgery and are associated with increased morbidity and mortality. Urine biomarkers may allow for earlier diagnosis of AKI, but their role, time course, and association with FO in infants is incompletely characterized. We aim to characterize the association between urine neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule-1 (uKIM1), and cystatin C (uCysC) and AKI and FO in infants after heart surgery. Methods: We performed a single-center ancillary prospective cohort study of infants < 1 year old who underwent heart surgery and were enrolled in the STRESS trial (NCT03229538) from June 2019-May 2020. We excluded preterm infants and those who had preoperative AKI, as defined per the modified KDIGO criteria. Our primary outcome was development of any KDIGO defined AKI. Our secondary outcome was development of ≥10% FO 48 hours postoperatively. Urine samples were collected at three time points (preoperative, 0-< 8 hours post-bypass, 8-24 hours post-bypass). We examined the association between standardized urine biomarker values and AKI and FO using multivariable analysis controlling for demographics, surgical factors, and surrogate markers of illness severity. Results: Our cohort included 40 infants with a mean of 2 urine samples each. Median (IQR) age at surgery was 103 (5.5-161) days. A total of 22 (55%) infants were diagnosed with any AKI and 21 infants (53%) developed FO. No infant died. In unadjusted analysis, bypass time was longer (171 [106, 222] v 111 [75, 155] minutes, p=0.01), and vasoactive infusion score was higher (9.5 [6, 11.5] v 5 [2, 9.5], p=0.02) in infants with AKI compared to those without AKI. On multivariable analysis, higher levels of uCysC and uNGAL at 0-8 hours post-bypass were predictive of FO at 48 hours (OR:3.4; 95% CI: 1.3, 8.9; OR: 2.7; 95% CI: 1.2, 6.2, respectively). There was no significant correlation between uCysC, uNGAL, and uKIM1 at any time and AKI. Conclusions: In a single center cohort, uCysC and uNGAL in the early postoperative period were associated with FO at 48 hours postoperatively. UCysC, uNGAL, and uKIM1 were not associated with AKI. Further studies should focus on the role of urine biomarkers in early diagnosis of FO.