PB1035 Monitoring of Unfractionated Heparin in Critical ill ICU Patients: A Prospective Study Comparing aPTT and Point-of-Care Viscoelastic Testing with IN/HI Ratio to Anti-Xa

Introduction Anticoagulation is indicated for the prevention or therapy of thromboembolic events, but remains highly challenging considering the high risk of bleeding events in critically ill patients.Unfractionated heparin (UFH) is widely used as preferred anticoagulation for patients on intensive care units (ICU) due to its beneficial short half time and fast elimination. For monitoring of UFH, activated partial thromboplastin time (aPTT) is mainly used, but aPTT can be misleading in both directions [1]. While high factor VIII plasma values may decrease aPTT, a reduced factor XII under extracorporal circulation may prolong aPTT that no longer correlates to anticoagulation intensity [2]. Anticoagulation monitoring using specific UFH calibrated anti-Xa levels is an established alternative to overcome aPTT limitations but is rarely available 24/7 [3] [4]. Using point-of-care (POC) viscoelastic testing (VET) [5] with a specific ratio between clotting time (CT) in intrinsic test (IN-test) compared to heparinase test (HI-test) – which includes the inactivation of heparin in the probe - might help to determine the UFH effect in critically ill patients [6].