Continuous intravenous infusion of enoxaparin controls thrombin formation more than standard subcutaneous administration in critically ill patients. A sub-study of the ENOKSI thromboprophylaxis RCT

Abstract

Introduction: Standard subcutaneous low-molecular-weight heparin (LMWH) thromboprophylaxis yields low anti-factor Xa activity in patients in the intensive care unit (ICU). The aim of the study was to assess coagulation status in ICU patients randomized to receive enoxaparin thromboprophylaxis either as a standard subcutaneous bolus (SCB) or continuous intravenous infusion (CII) for 3 consecutive days after the initiation of LMWH thromboprophylaxis.

Materials and methods: Thirty-eight patients were studied by conventional coagulation variables: prothrombin fragment F 1+2 (F 1+2) representing FXa inhibition and antithrombin (AT). Additionally, 18 patients were analyzed by the thrombin generation assay-calibrated automated thrombogram (TGA-CAT). Blood samples were collected before the initiation of the LMWH thromboprophylaxis (ie, baseline), at 51 h, and at 72 h.

Results: At beginning, no differences in coagulation biomarkers were observed. The levels of F 1+2 were significantly lower at 51 and 72 h in the CII group than in the SCB group. AT levels increased during the follow-up in the CII group, unlike in the SCB group. TGA-CAT was poor in some patients overall. In a subset of patients at 51 h lag time (4.3 vs 7.5 min, respectively, P < 0.05) and time to peak (7.7 vs 14.3 min, respectively, P < 0.05) were prolonged in the SCB group. At 72 h, however, peak thrombin was lower in the CII than in the SCB group: 271 vs 356 nM, respectively (P < 0.05).

Conclusions: Enoxaparin thromboprophylaxis administered by CII inhibited more prominently FXa and preserved better the AT level, compared with standard subcutaneous care.

Keywords: Blood Coagulation Factor; Enoxaparin; Heparin; Intensive Care Unit; Low-Molecular-Weight; Thromboprophylaxis.