Comparison of the injection of low molecular weight heparin in arterial or venous bloodline for preventing extracorporeal circuit clotting during hemodialysis

Introduction Low molecular weight heparins (LMWH) are widely used for preventing clotting during hemodialysis (HD). Although injection in venous bloodline (VBL) is recommended to avoid initial loss of LMWH through the dialyzer, LMWH is still frequently administered in the arterial blood line (ABL) at the start of dialysis. Description The aim of this study was to compare the efficacy and safety of same enoxaparin dose administered through VBL or ABL. We also evaluated antifactor Xa (aXa) activity according to the injection route and dialysis modalities: high-flux (HF) HD, medium cut-off (MCO) HD and on-line hemodiafiltration (OL-HDF). Methods This open, single-center prospective study was conducted at the Poitiers university Hospital HD unit. Forty-three patients were studied over 18 consecutive dialysis sessions using a fixed enoxaparin dose (20 or 40 mg) first administered through ABL bolus and then through VBL for another 18 sessions. Results Compared to ABL, VBL bolus resulted in significant increase in median post-dialysis aXa activity: 0.16 (0.1–0.6) IU/mL vs. 0.31 (0.1–1.3) IU/mL, respectively, P = 0.006. After ABL bolus of enoxaparin 40 mg, median post-dialysis aXa activity was significantly lower with OL-HDF compared to HF-HD: 0.14 (0.1–0.35) vs. 0.32 (0.15–0.49), P = 0.02. A trend for lower clotting within lines and bubble trap using VBL bolus was observed. Conclusion In conclusion, VBL enoxaparin injection is safe in OL-HDF patients. However, in HF-HD and MCO-HD, VBL injection of enoxaparin 40 mg may increase overdosing risk. Thus, aXa activity should be monitored in HF-HD and MCO-HD patients at risk of bleeding and/or on vitamin K antagonists, and careful surveillance is required when administering enoxaparin dose 40 mg through the VBL route.