Evaluation of Anti-Xa and Activated Partial Thromboplastin Time Monitoring of Heparin in Adult Patients Receiving Extracorporeal Membrane Oxygenation Support

The approach to monitoring anticoagulation in adult patients receiving heparin on extracorporeal membrane oxygenation (ECMO) support is controversial. The objective of this study was to compare the correlation between anti-Xa and activated partial thromboplastin time (aPTT) with heparin dose and to describe their association with clinical events in adult ECMO patients. We conducted a retrospective single-center study of 34 adult ECMO patients whose heparin was monitored by anti-Xa and/or aPTT. The heparin dose-to-assay correlation coefficient was 0.106 for aPTT and 0.414 for anti-Xa (p < 0.001). Major thrombotic and hemorrhagic events occurred in 14.7% and 26.5% of patients, respectively. The median anti-Xa in patients who experienced a major thrombotic event was 0.09 (0.06-0.25) IU/mL compared with 0.36 (0.26-0.44) IU/mL in patients who did not (p = 0.031), whereas the median aPTT did not differ between these groups. The maximum aPTT in patients who experienced a major bleed was 96.9 (76.0-200) seconds compared with 63.5 (44.4-98.6) seconds in patients who did not (p = 0.049), whereas the maximum anti-Xa did not differ between these groups. Monitoring both anti-Xa and aPTT may be warranted to safely provide understanding of pure heparin activity as well as underlying bleeding diatheses in adult ECMO patients.