**6.1 Unfractionated heparin**

UFH is a commonly used anticoagulant for CRRT. It works by binding to antithrombin III, which subsequently inhibits thrombin and other coagulation factors. Dosing is typically titrated to achieve a target activated partial thromboplastin time (aPTT) or activated clotting time (ACT). Typical ranges for aPTT are between 45–60 seconds and 180–220 seconds for ACT. UFH carries the often-cumbersome need for careful monitoring of the patient's clotting function and frequent dosing adjustments to maintain the target aPTT or ACT.
