Correlation among Hemolysis Biomarkers in Pediatric Patients Undergoing Extracorporeal Membrane Oxygenation

Hemolysis is a common complication associated with mortality on extracorporeal membrane oxygenation (ECMO). Plasma-free hemoglobin (PFH) is the most commonly used biomarker reported for hemolysis on ECMO. This test is not readily available at all institutions, and other more readily available tests may indicate hemolysis nearly as well or as well as PFH. The purpose of this study was to study the correlation of other biomarkers of hemolysis to PFH on ECMO. All patients younger than 21 years placed on ECMO in a quaternary children's hospital between January 2013 and December 2016 were included in the study; biomarkers (urine hemoglobin [U-Hb], PFH, lactate dehydrogenase [LDH], aspartate aminotransferase [AST], gross hemolysis, and red cell distribution width (RDW)) were collected from the medical record. Descriptive statistics and repeated bivariate analyses were determined using SPSS 22.0. The median age on day 0 of ECMO was 29 days (.08 years) (IQR: 2; 319 days (.005; .875 years)). The median weight was 3.9 kg (IQR: 2.8; 8.6), and the median total duration of the ECMO run was 10.48 days (IQR: 4.25; 14), with 82% of all the patients being on venoarterial ECMO. There was no correlation between hematuria on urinalysis and the level of PFH (p = .338). There was a statistically significant positive correlation between PFH and the following respective biomarkers: gross hemolysis on the routine chemistry studies (p < .01, Rho = .439), AST (p < .01, Rho = .439), RDW (p < .01, Rho = .190), LDH (p < .01, Rho = .584), and AST (when associated elevated alanine transaminase (ALT) levels were censored) (p < .01, Rho = .552). U-Hb correlated poorly with PFH. The serum biomarkers AST (in the absence of ALT elevation) and LDH can be useful surrogates for PFH to quantify hemolysis on ECMO in pediatric patients.