Activated Clotting Times Demonstrate Weak Correlation With Heparin Dosing in Adult Extracorporeal Membrane Oxygenation.

Abstract

The optimal monitoring strategy for anticoagulation management in extracorporeal membrane oxygenation (ECMO) remains a clinical controversy. The Extracorporeal Life Support Organization Anticoagulation Guidelines suggest that multiple anticoagulation assays may be needed but do not specify a preferred management strategy. In adult ECMO patients, which anticoagulation assays demonstrate the highest correlation with unfractionated heparin (UFH) dose requirements? We performed a retrospective chart review of adult patients cannulated to ECMO between February 2013 and July 2015. The primary outcome was the correlation between activated clotting time (ACT), activated partial thromboplastin time (aPTT), and anti-Xa and UFH dose. Secondary outcomes included correlations between anticoagulation assays. Correlations were calculated for the entire cohort, with subgroup analysis of venoarterial and venovenous ECMO patients. Forty-eight patients were included in the analysis, 26 initially cannulated to venoarterial ECMO and 22 to veno-venous ECMO. The median duration of ECMO therapy was 7 days. Mean UFH requirements were 1149 units/h or 15.3 units/kg/h. Total UFH dose was most correlated with anti-Xa levels (r = 0.467), whereas weight-based heparin dose was most correlated with aPTT (0.405). For correlations between anticoagulation assays, anti-Xa and aPTT were more highly correlated with each other (r = 0.633) compared with ACT. In adult patients requiring ECMO, anti-Xa and aPTT monitoring were correlated more closely with UFH dosing than ACT.