(1422) Evaluating Circuit Filter Clotting During CRRT in Patients Receiving Subtherapeutic Anticoagulation

Introduction: Continuous renal replacement therapy (CRRT) is a common intervention in the intensive care unit. Anticoagulation is often utilized to prevent filter clotting. Unfractionated heparin (UFH) is an appealing option for anticoagulation in CRRT because of the availability, ease of monitoring, and low cost as compared to regional citrate anticoagulation. This study assessed the filter clotting rates at an institution using a subtherapeutic heparin infusion protocol to maintain CRRT filter patency.

Methods: A retrospective chart review was conducted from July 2022 to May 2023. Patients were included if they were over 18 years old and received uninterrupted CRRT for at least 12 hours. Patients were excluded if they had an indication for therapeutic anticoagulation. The primary outcome was the median number of clotted filters per patient. Key secondary outcomes were percentage of patients requiring anticoagulation escalation and percentage of patients receiving venous thromboembolism (VTE) prophylaxis in addition to subtherapeutic heparin. The primary safety outcome was the rate of bleeding events.

Results: 74 patients were included during the study period. The most common indication for CRRT was acute kidney injury (56.8%) with a median CRRT duration of 4.1 days (IQR 6.3 days). There was a median of 1.5 clotted filters per patient (IQR 1.0), with most patients experiencing zero clotted filters (54.1%). 34 patients required anticoagulation escalation to maintain filter patency (45.9%). The most common escalation was from no anticoagulation to subtherapeutic heparin. Patients frequently received VTE prophylaxis in addition to subtherapeutic heparin (70.2%). There were 11 bleeding events (14.8%).

Conclusions: A subtherapeutic heparin protocol resulted in low rates of CRRT filter clotting.