246 - Acute Kidney Injury (AKI), Urine Neutrophil Gelatinase-Associated Lipocalin (NGAL), Serum Cystatin C (Cys C), and Markers of Hemolysis in Children Undergoing Cardiopulmonary Bypass (CPB)

Poster Number: 246
Publication Number: 246.25

Lane Lanier, TCU and UNTHSC School of Medicine, Crowley, TX, United States; Fadeke Ogunyankin, Cook Children's Medical Center, Fort Worth, TX, United States; Christopher Tsao, Cook Children's Medical Center, Southlake, TX, United States; James D. Marshall, Cook Children's Medical Center, Fort Worth, TX, United States

Background: Acute kidney injury (AKI) incidence varies in the pediatric cardiac intensive care unit (CICU) and has an associated mortality of 20-79%. Development of AKI is associated with prolonged cardiopulmonary bypass (CPB) time, prolonged ventilation and increased length of hospital stay. A potential factor for increased CPB time and AKI is increased hemolysis. Plasma free hemoglobin (PHb), a marker of hemolysis, is associated with oxidative stress and renal injury. Diagnosis and severity of AKI relies upon serum creatinine (Cr) and urine output. Urine NGAL and serum Cys C are biomarkers utilized to help detect AKI after CPB.

Objective: This study's primary objective was determining feasibility defined as >80% of patients approached being recruited, attrition rate throughout study of < 10%, and recruitment of 20 patients within 1 year. In addition, determining the pattern of urine NGAL and serum Cys C elaboration and decay after subjects with ventricular septal defects (VSD), Tetralogy of Fallot (TOF), and balanced atrioventricular canal defect (AVCD) underwent repair with CPB and modified ultrafiltration (MUF). We correlate these biomarker levels with the presence of AKI and with markers of hemolysis.

Design/Methods: This is a single-center prospective pilot cohort study of patients undergoing surgical repair of VSD, TOF, and AVCD.  Male or female subjects greater than 28 days of age but less than 18 years of age were included. Subjects with postsurgical care in the CICU, normal preoperative serum creatinine and no history of AKI were included. KDIGO guidelines were utilized to determine AKI.  Baseline levels of serum Cr, urine NGAL, Cys C, PHb, lactate dehydrogenase (LDH), and haptoglobin were obtained. Time zero was the end of CPB. Repeat levels were obtained at 2 hours (h), 12h, 24h, and 48h.

Results: Twenty-three consecutive patients met criteria with 3 declining enrollment. One patient did not complete the study. Four patients developed AKI (incidence 20%). No significant difference occurred in gender, race, BMI, cross-clamp time, CPB time, time to extubation, MUF time and volume in those with and without AKI. No significant difference occurred in urine NGAL values in those with and without AKI.  Cys C levels were significantly lower in patients without AKI at 12h. No significance was noted in markers of hemolysis between those with and without AKI.

Conclusion(s): Two out of 3 feasibility criteria were met. Recruitment took 18 months. Patients with VSD, TOF, and AVCD who developed AKI didn't have statistically different AKI biomarkers or markers of hemolysis compared with those who did not develop AKI.