Urinary biomarkers and renal near-infrared spectroscopy predict intensive care unit outcomes after cardiac surgery in infants younger than 6 months of age

Abstract

Objective: To assess the ability of urinary acute kidney injury biomarkers and renal near-infrared spectroscopy (NIRS) to predict outcomes in infants after surgery for congenital heart disease.

Methods: Urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), and cystatin C were measured preoperatively and postoperatively in 49 infants younger than 6 months of age. Renal NIRS was monitored for the first 24 hours after surgery. A composite poor outcome was defined as death, the need for renal replacement therapy, prolonged time to first extubation, or prolonged intensive care unit length of stay.

Results: Forty-two (86%) patients had acute kidney injury as indicated by at least Acute Kidney Injury Network/Kidney Disease: Improving Global Outcomes (AKIN/KDIGO) stage 1 criteria, and 17 (35%) patients had poor outcomes, including 3 deaths. With the exception of KIM-1, all biomarkers demonstrated significant increases within 24 hours postoperatively among patients with poor outcomes. Low levels of NGAL and IL-18 demonstrated high negative predictive values (91%) within 2 hours postoperatively. Poor outcome infants had greater cumulative time with NIRS saturations less than 50% (60 vs 1.5 minutes; P = .02) in the first 24 hours.

Conclusions: Within the first 24 hours after cardiopulmonary bypass, infants at increased risk for poor outcomes demonstrated elevated urinary NGAL, IL-18, and cystatin C and increased time with low NIRS saturations. These findings suggest that urinary biomarkers and renal NIRS may differentiate patients with good versus poor outcomes in the early postoperative period, which could assist clinicians when counseling families and inform the development of future clinical trials.

Keywords: 41.3; AKI; AKIN; Acute Kidney Injury Network; CPB; ECMO; ICU; IL-18; KDIGO; KIM-1; Kidney Disease: Improving Global Outcomes; NGAL; NIRS; RACHS-1; RIFLE; RIFLE criteria modified to pediatrics; RRT; Risk Adjustment for Congenital Heart Surgery 1; Risk, Injury, Failure, Loss, End-stage kidney disease; S(Cr); acute kidney injury; cardiopulmonary bypass; extracorporeal membrane oxygenation; intensive care unit; interleukin 18; kidney injury molecule-1; near-infrared spectroscopy; neutrophil gelatinase-associated lipocalin; pRIFLE; rSO(2); regional oxyhemoglobin saturation; renal replacement therapy; serum creatinine.

Conflict of interest statement

The authors have no conflicts of interest to report.

Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Figures

Figure 1

Biomarker profiles in infants undergoing cardiopulmonary bypass. Urinary concentrations of NGAL (panel A), IL-18 (panel B), Cystatin C (panel C), and KIM-1 (panel D) were determined by ELISA as described in the Methods. Data are presented as median values in the good outcome (grey dotted line) vs poor outcome (solid black line) groups. Error bars indicate interquartile range (25th–75th percentile). * = P