Clinically suspected heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

PurposePatients 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 methodsWe conducted a retrospective review in adult patients on ECMO. Patients were included if they received ECMO for at least 5 days and concomitant UFH.ResultsThere were 119 patients who met inclusion criteria. Twenty-three patients (19%) had a heparin-platelet factor 4 immunoassay performed. Patients with suspected HIT had a significantly lower platelet count within the first 3 days of ECMO, 69 × 109/L (22-126 × 109/L) vs 87.5 × 109/L (63-149 × 109/L); P = .04. The lowest platelet count on the day of HIT testing was 43 × 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.ConclusionsThe 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.