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Correlation Among Antifactor Xa, Activated Partial Thromboplastin Time, and Heparin Dose and Association with Pediatric Extracorporeal Membrane Oxygenation Complications

McMichael, Ali B. V.*; Hornik, Christoph P.†,‡; Hupp, Susan R.*; Gordon, Sharon E.§; Ozment, Caroline P.

doi: 10.1097/MAT.0000000000000986
Original Article: PDF Only

Anticoagulation is essential during extracorporeal membrane oxygenation (ECMO) to prevent catastrophic circuit clotting. Several assays exist to monitor unfractionated heparin (UFH), the most commonly used anticoagulant during ECMO, but no single test or combination of tests has consistently been proven to be superior. This retrospective observational study examines the correlation among antifactor Xa level, activated partial thromboplastin time (aPTT), and UFH dose and the association between antifactor Xa level and aPTT with survival and hemorrhagic and thrombotic complications. Sixty-nine consecutive neonatal and pediatric ECMO patients from September 2012 to December 2014 at a single institution were included. Spearman rank correlation was used to compare antifactor Xa level, aPTT, and UFH dose. Significant but poor correlation exists between antifactor Xa level and UFH dose ρ = 0.1 (p < 0.0001) and aPTT and UFH dose ρ = 0.26 (p < 0.0001). Antifactor Xa level and aPTT were weakly correlated to each other ρ = 0.38 (p < 0.0001). In an univariate analysis, there was no difference between survival and antifactor Xa level, aPTT, or UFH dose. Multiple anticoagulation tests may be superior to a single test during ECMO.

From the *Department of Pediatrics, UT Southwestern, Dallas, Texas

Department of Pediatrics, Duke University Hospital, Durham, North Carolina

Duke Clinical Research Institute, Durham, North Carolina

§Department of Pharmacy, Children’s Hospital Colorado, Aurora, Colorado.

Submitted for consideration August 2018; accepted for publication in revised form January 2019.

Disclosure: Dr. Hornik receives salary support for research from the National Center for Advancing Translational Sciences of the National Institutes of Health (UL1TR001117) and the U.S. government for his work in pediatric and neonatal clinical pharmacology (Government Contract HHSN267200700051C; PI: Benjamin under the Best Pharmaceuticals for Children Act). The other authors have no conflicts of interest to report.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML and PDF versions of this article on the journal’s Web site (

Reprint Requests: Caroline P. Ozment, MD, Department of Pediatrics, Duke University Hospital, 2300 Erwin Road-DUMC 3046, Duke North Suite 5260Y, Durham, NC 27710. Email:

Copyright © 2019 by the American Society for Artificial Internal Organs