The need for continuous anticoagulation is the weak point of CRRT. The low-flow low-pressure conditions of the arteriovenous techniques increase the risk of filter clotting. Procedures to reduce the anticoagulant requirements are thorough rinsing of the filter before use in order to avoid all blood-air contact, ensuring maximal blood flow by reducing all resistances in the extracorporeal circuit, use of predilution, and frequent filter flushing with saline.
Extracorporeal anticoagulation can be achieved by prefilter administration of standard heparin (5-10 IU/kg/h), low-molecular-weight heparin, epoprostenol (prostacyclin) or its analogs (5-10 ng/kg/min), citrate, or nafamostate mesylate. Each of these methods has advantages and drawbacks.
When titrating the anticoagulant the primary goal should be avoidance of hemorrhagic complications and not prolongation of filter life. If bleeding risk is high, anticoagulant administration should be minimized or even omitted and frequent filter clotting must be accepted. In patients with severe coagulopathy, a satisfactory filter lifespan can be achieved without anticoagulation.
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