Clinically suspected heparin-induced thrombocytopenia during extracorporeal membrane oxygenation

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).

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.

There 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, 69×10(9)/L (22-126×10(9)/L) vs 87.5×10(9)/L (63-149×10(9)/L); P=.04. The lowest platelet count on the day of HIT testing was 43×10(9)/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.

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.