Repeated early hemofiltration filters clotting and heparin-induced thrombocytopenia in ICU

Repeated early hemofiltration filter clotting are real thrombotic events. Diagnosis of heparin-induced thrombocytopenia (HIT) in this setting in ICU remains difficult. We describe two cases of repeated early hemofiltration filters clotting in ICU and to evaluate their impact on the probability test 4T's score and diagnosis of HIT. Two patients undergoing at least three repeated early hemofiltration clotting filters in <6 h revealing HIT in ICU had a low probability score for HIT. Despite a 4T's score of three for the two patients and persistent early hemofiltration clotting filters, functional tests for HIT antibodies (heparin induced platelet activation assay and serotonin release assay) were positive, permitting the diagnosis of HIT in both patients. We suggest that the occurrence of repeated, rapid (within 6 h) hemofiltration filter clotting should score as two points for "Thrombosis" in the 4T's scoring system, thereby increasing the pretest probability for HIT in this clinical situation.