Platelet Count Trends and Prevalence of Heparin-Induced Thrombocytopenia in a Cohort of Extracorporeal Membrane Oxygenator Patients

Abstract

Objectives: To assess the prevalence of heparin-induced thrombocytopenia and to study platelet count trends potentially suggestive of heparin-induced thrombocytopenia in a population of extracorporeal membrane oxygenator patients.

Design: Retrospective cohort study.

Setting: A total of 926-bed teaching hospital.

Patients: Extracorporeal membrane oxygenator patients who survived longer than 48 hours from extracorporeal membrane oxygenator initiation between January 1, 2009, and December 31, 2013.

Interventions: None.

Measurements and main results: Demographic and clinical data were collected prospectively on all extracorporeal membrane oxygenator patients. Heparin-induced thrombocytopenia testing results and platelet count variables were obtained from the electronic medical record. We used our institutional algorithm to interpret the results of heparin-induced thrombocytopenia testing. Ninety-six extracorporeal membrane oxygenator patients met the inclusion criteria. Eight patients met the algorithm criteria for heparin-induced thrombocytopenia diagnosis and seven of those had documented thromboembolic event while on extracorporeal membrane oxygenator (prevalence of heparin-induced thrombocytopenia and heparin-induced thrombocytopenia related thrombosis, 8.3 and 7.3, respectively). Heparin-induced thrombocytopenia positive patients were younger; all underwent venoarterial extracorporeal membrane oxygenator; spent more hours on extracorporeal membrane oxygenator; had significantly higher heparin-induced thrombocytopenia enzyme-linked immunosorbent assays optical density; had a higher prevalence of thromboembolic events and reached platelet count nadir later. There was no difference in mortality between heparin-induced thrombocytopenia positive and negative patients. Comparison of platelet count trends revealed that there was no statistically significant difference between the predefined study groups.

Conclusions: Prevalence of heparin-induced thrombocytopenia and heparin-induced thrombocytopenia-related thrombosis among extracorporeal membrane oxygenator patients at our institution is relatively high. Using platelet count trends to guide decision to test for heparin-induced thrombocytopenia is not an optimal strategy in extracorporeal membrane oxygenator patients. Without a validated pretest probability clinical score, serosurveillance in a defined high-risk group of extracorporeal membrane oxygenator patients may be needed.