(1313) Characterization of Prefilter Heparin in Continuous Renal Replacement Therapy

Introduction: Pre-filter heparin is often used to prevent filter clotting in continuous renal replacement therapy (CRRT). Associated concerns include variability in guidance for use and bleeding risk. This study sought to characterize utilization of pre-filter heparin in CRRT.

Methods: A retrospective, single-arm, single-center cohort study was conducted among patients admitted to intensive care units (ICUs) at an academic medical center in Philadelphia between January 1, 2020 and August 1, 2022. Patients were included if they received pre-filter heparin at a fixed rate. The primary aim was to define the median infusion rate and duration of pre-filter heparin. Secondary aims included the following: quantifying adverse events (i.e. clotting, bleeding, heparin-induced thrombocytopenia and associated lab values), CRRT prescriptions, interventions to improve line viability, and utilization of prophylactic anticoagulation.

Results: Of 187 patients screened, 150 met criteria and were included. The median infusion rate was 500 units per hour and the median duration was 52.4 hours. Following pre-filter heparin initiation, there was a significant decrease in the mean number of clotting events from 3.4 to 2.6 (p = 0.015), but no significant difference in time to first clotting event (p = 0.978). There was a statistically significant increase from patients’ baseline prothrombin time (PTT) to maximum PTT while receiving pre-filter heparin (p < 0.001). Patients who experienced bleeding events showed greater increases in PTT compared to those who did not; however, this was not statistically significant (p = 0.082).

Conclusions: In critically ill patients receiving CRRT, administration of pre-filter heparin decreased filter clotting events but did not increase the time to first clotting event. Additionally, this came at the cost of a statistically significant elevation in PTT, which may contribute to an increased risk of bleed.