Clinically suspected heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

Purpose: Patients receiving extracorporeal membrane oxygenation (ECMO) are at risk for thrombocytopenia including heparin-induced thrombocytopenia (HIT). The purpose of this study was to determine the frequency of suspected HIT in patients receiving ECMO and unfractionated heparin (UFH). Materials and methods: We conducted a retrospective review in adult patients on ECMO. Patients were included if they received ECMO for at least 5 days and concomitant UFH. Results: There were 119 patients whomet inclusion criteria. Twenty-three patients (19%) had a heparin-platelet factor 4 immunoassay performed. Patientswith suspected HIT had a significantly lower platelet count within the first 3 days of ECMO, 69 x 10(9)/L (22-126 x 10(9)/L) vs 87.5 x 10(9)/L (63-149 x 10(9)/L); P=.04. The lowest platelet count on the day of HIT testing was 43 x 109/L (26-73), representing a 71% reduction from baseline. Twenty patients (87%) had an optical density score less than 0.4, and all patients had a score less than 1.0. A functional assay was performed in 7 patients (30%), with only 1 patient having laboratory-confirmed HIT. Conclusions: The evaluation of HIT occurred in a small percentage of patients, with HIT rarely being detected. Patients who had heparin-platelet factor 4 immunoassay testing exhibited lower platelet counts with a similar duration of ECMO and UFH exposure. (C) 2015 Elsevier Inc. All rights reserved.