Monitoring of Low Molecular Weight Heparin Thromboprophylaxis with Alternative Methods to Anti-Factor Xa

Abstract

Introduction: Initiating low molecular weight heparin (LMWH) thromboprophylaxis too early in patients with traumatic braininjury increases the risk of intracranial bleeding. Therefore, it is important to monitor LMWH and asses when it is safe to initiate.The aim of this research was to study alternative monitoring methods for LMWH than the standard method anti-factor Xa (antiFXa), and to investigate the peak anti-FXa level. We hoped to answer “How do rotational thromboelastometry (ROTEM) andSonoclot change at different LMWH concentrations added in vitro to blood from intensive care patients? How do point of careparameters change after subcutaneous LMWH administration on healthy volunteers with consecutive measurements to catch thepeak effect?”.Methods: Different concentrations of enoxaparin were added in vitro to citrated whole blood from fifteen intensive care patients.The first ten patients’ coagulation was analysed with ROTEM using the INTEM and NATEM assays, and the last five withSonoclot with a kaolin activator and ROTEM INTEM. Previously collected data was used from nine healthy volunteers that hadreceived subcutaneous enoxaparin. Citrated blood samples were collected before and after LMWH initiation and analysed withSonoclot kaolin and a chromogenic anti-FXa-assay. Friedman test, Dunn’s multiple comparison test and Spearman’s correlationtest were performed.Results: ROTEM INTEM CT, CFT, A10 and MCF were significantly affected with increasing in vitro enoxaparin from 0.4anti-FXa concentration. ROTEM NATEM CT was also prolonged at this LMWH concentration. Sonoclot’s parameters didn’tsignificantly change with increasing in vitro enoxaparin. The peak of in vivo LMWH was reached after 2 to 4 hours with avariation of peak anti-FXa between 0.3-0.5 IU/mL.Conclusions: ROTEM INTEM CT performed best and was prolonged at anti-FXa from 0.4-0.6 IU/mL. ROTEM INTEM shouldbe tested in neurointensive care to increase the safety of LMWH thromboprophylaxis and possibly to individualize the dosage. (Less)