Annamarie Versele
Pronouns: she/her
Research Mentor(s): Alvaro Rojas-Peña
Research Mentor School/College/Department: Department of Surgery-Transplantation / Medicine
Program:
Authors: Kathryn Loftus, Annamarie Versele, Daniela Pelaez-Palacio, Megan Stein, Robert Bartlett, Alvaro Rojas-Pena, George Mychaliska
Session: Session 6: 3:40 pm – 4:30 pm
Poster: 18
Abstract
Understanding Hemolysis Indicators in Neonates on Extracorporeal Life Support: A Retrospective Study Using a Lamb Model Kathryn Loftus1; Annamarie Versele1; Daniela Pelaez-Palacio, MD1; Megan Stein, BS1; Robert Bartlett, MD1; Alvaro Rojas-Pena, MD1,2; George B. Mychaliska, MD1,3,4 1. Department of Surgery, Extracorporeal Life Support (ECLS) Lab, University of Michigan. 2. Department of Surgery, section of Transplant surgery, University of Michigan. 3. Department of Surgery, section of Pediatric surgery, University of Michigan. 4. Department of Obstetrics and Gynecology, University of Michigan. INTRODUCTION For over fifteen years the Extracorporeal Life Support (ECLS) lab has used a lamb model to test a modified ECLS system, called the “artificial placenta (AP)” which maintains fetal circulation, provides respiratory and metabolic support, and allows for organ development in premature animals. While on ECLS, intravascular hemolysis is a frequently seen occurrence, leading to the need for frequent transfusions to maintain physiological parameters and avoid complications. The aim of this study is to pinpoint the factors indicative of hemolysis in a premature lamb model undergoing AP support, focusing on impact seen on different prematurity levels. METHODS The study was performed in a retrospective observational fashion. Two groups of premature lambs at different estimated gestational age (EGA) were studied. Group A: EGA >115 days; Group B: EGA <115 days; n=4 per group). Under general anesthesia the ewe was instrumented for a c-section delivery of the premature lamb. The lamb was instrumented for venous-venous (V-V) cannulation via jugular and umbilical veins and AP support initiated and maintained for at least 72 hours. Variables observed were sex (male vs female), blood flow required for support (70-120mL/kg/min), Hemoglobin (>10g/dL), reticulocyte count (<5%), plasma-free hemoglobin (<5 mg/dL no hemolysis, 5-10 mg/dL low hemolysis, >50 mg/dL high hemolysis), total and indirect bilirubin (> 5 mg/dL, with increase in indirect bilirubin >0.8 mg/dL). Data is presented in means and standard deviations. RESULTS Placenta support was maintained for at least 72 hours in all animals. Within Group A, the females had lower plasma free hemoglobin levels than males (37 mg/dL ±2.05 vs 44 mg/dL ±2.5). Within Group B, all animals averaged a plasma free hemoglobin level of 71 mg/dL (± 9.12) indistinct of sex. Animal blood flow was maintained at target. Hemoglobin levels were below expected for ECLS (Group A, 9.8±0.7 g/dL; vs Group B, 9.9±0.5 g/dL). Reticulocyte count was not collected in Group A, whereas levels were sustained high throughout animal support in Group B (26.2 % ±6). Bilirubin levels increased in both groups posterior to the initial 24 hours, with peak total and indirect bilirubin elevation during 48-72 hours on support, and remained within significant hemolysis parameters throughout the experimental time. CONCLUSION Plasma free hemoglobin and indirect bilirubin levels show accuracy at determining hemolysis in these neonates, however, in the more premature significantly higher levels of hemolysis are seen. Further studies need to be performed to increase the power of these results.
