CardiovascularClinically suspected heparin-induced thrombocytopenia during extracorporeal membrane oxygenation
Introduction
Extracorporeal membrane oxygenation (ECMO) is a form of mechanical circulatory support used in critically ill patients with respiratory or cardiac failure. Systemic anticoagulation is used to mitigate the thrombotic complications that may occur when blood is exposed to artificial surfaces within the ECMO circuit [1]. Unfractionated heparin (UFH) is the most common anticoagulant used to prevent the formation of thrombus within the ECMO circuit [1]. A rare but potential serious adverse effect of UFH is immune-mediated heparin-induced thrombocytopenia (HIT), with an incidence as high as 5%, depending on the patient population [2], [3]. However, the incidence of HIT in patients receiving ECMO is not well characterized [4], [5], [6].
The diagnosis of HIT is based on both clinical suspicion and pathologic confirmation. Clinical suspicion of HIT typically occurs with declining platelet counts in the setting of active heparin use. However, thrombocytopenia in critically ill patients is often multifactorial and may be due to various inciting events. The use of mechanical circulatory support can simultaneously result in thrombocytopenia and thrombosis through platelet activation and consumption, mimicking the presentation of HIT [1], [7]. In addition, mechanical circulatory support may influence the development of HIT as a result of continued platelet activation and ongoing release of platelet factor 4 (PF4) [8], [9]. This retrospective review will evaluate the frequency of suspected HIT in patients receiving ECMO in a single, academic medical center.
Section snippets
Patients
This was a retrospective chart review of all patients who received ECMO between January 2011 and June 2013. Patients were included if they were at least 18 years of age, had no prior history of HIT, were anticoagulated with UFH within 24 hours of ECMO initiation, and received ECMO for at least 5 continuous days. The study was approved by the institutional review board. Individual patient consent was waived because of the retrospective nature of the study.
Anticoagulation in ECMO
Our institutional guideline for the
Patient characteristics
Our cohort consisted of 119 patients, 19% of whom had a clinical suspicion of HIT. Baseline demographic data are listed in Table 1. Groups were similar with respect to age, weight, comorbidities, ECMO configuration, and baseline platelet count. Thirty percent of cardiac patients had HIT testing sent compared to 7.5% of medical patients (P = .08). Although patients with clinical suspicion of HIT had a higher median APACHE II score as compared to those who did not (25 vs 22; P = .06), it was not
Discussion
In this cohort of 119 adults receiving ECMO and UFH, we found that 19% of patients had clinical suspicion of HIT, with only 1 patient having laboratory-confirmed HIT. Patients suspected of HIT had significantly lower platelet counts with a similar duration of ECMO, baseline platelet count, and total UFH exposure. We found no significant differences in ICU and hospital lengths of stay, but significantly higher inhospital mortality in patients suspected of HIT.
Thrombocytopenia, typically defined
Conclusions
In conclusion, although the suspicion of HIT occurs frequently in patients supported with ECMO, there appears to be a very low incidence of laboratory-confirmed HIT. This clinical problem still remains elusive, as the low incidence in this cohort should not preclude further evaluation. Nonetheless, incorrectly labeling a patient as having HIT has significant implications and should only be investigated after careful clinical evaluation.
Conflicts of interest
Daryl Glick: None
Amy L. Dzierba: None
Darryl Abrams: None
Justin Muir: None
Andrew Eisenberger: None
David Diuguid: None
Erik Abel: None
Cara Agerstrand: None
Matthew Bacchetta: None
Daniel Brodie: Research support and research consulting for Maquet Cardiovascular, Medical Advisory Board for ALung Technologies. All compensation paid to Columbia University.
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2022, Journal of Cardiothoracic and Vascular AnesthesiaThe Predictive Value of the 4Ts and HEP Score at Recommended Cutoffs in Patients With Mechanical Circulatory Support Devices
2022, Journal of Cardiothoracic and Vascular AnesthesiaCitation Excerpt :However, these results contrasted with recent consensus guidelines that recommend against further laboratory testing and empirical treatment for patients having suspected HIT and a low 4Ts (0-3).14 Unrecognized HIT in the general population and suspected HIT with ECMO are associated with increased mortality; thus, the development of an assessment tool with high sensitivity and NPV to assist in the early detection of HIT is vital.2,31 Limitations of this study included the retrospective study design and reliance upon accurate documentation in the medical record and utilization of medical coding terminology to identify patients who required MCS devices.
Analysis of the 2020 EACTS/ELSO/STS/AATS Expert Guidelines on the Management of Adult Postcardiotomy Extracorporeal Life Support
2022, Journal of Cardiothoracic and Vascular AnesthesiaNon-extracorporeal membrane oxygenation artificial circulatory support for postcardiotomy syndrome
2022, Cardiopulmonary Bypass: Advances in Extracorporeal Life Support2020 EACTS/ELSO/STS/AATS expert consensus on post-cardiotomy extracorporeal life support in adult patients
2021, Journal of Thoracic and Cardiovascular SurgeryCitation Excerpt :Clinically diagnosed HIT occurs in only 1%–3% of cases where heparin exposure continues postoperatively, with an associated mortality of 5%.130,134 The incidence is similar in patients with ECLS.131 A DTI, specifically bivalirudin or argatroban, should be used as the alternative to heparin when HIT is being considered, both to halt the immunostimulation leading to thrombocytopenia and to avoid the development of potentially lethal thrombotic thrombocytopenia, with its associated mortality of 50%.130,131,134
2020 EACTS/ELSO/STS/AATS Expert Consensus on Post-Cardiotomy Extracorporeal Life Support in Adult Patients
2021, Annals of Thoracic SurgeryCitation Excerpt :Clinically diagnosed HIT occurs in only 1–3% of cases where heparin exposure continues postoperatively, with an associated mortality of 5%.130,134 The incidence is similar in patients with ECLS.131 A DTI, specifically bivalirudin or argatroban, should be used as the alternative to heparin when HIT is being considered, both to halt the immunostimulation leading to thrombocytopenia and to avoid the development of potentially lethal thrombotic thrombocytopenia, with its associated mortality of 50%.130,131,134
- 1
Institution where work was completed: NewYork-Presbyterian Hospital, Columbia University Medical Center, 177 Fort Washington Avenue, New York, NY 10032. At the time of data collection, Daryl Glick was a PGY-2 Critical Care Pharmacy Resident at NewYork-Presbyterian Hospital. She now works at Mount Sinai Beth Israel.
- 2
Co-senior authors.