Abstract Number: PB/CO20
Meeting: ISTH 2020 Congress
Theme: Coagulation and Natural Anticoagulants » Critical Care and Perioperative
Background: Managing the coagulopathy of severe COVID-19 infection represents a unique challenge. COVID-19 infection is associated with increased thrombotic risk, however high rates of bleeding and intracranial hemorrhage have also been observed in COVID-19 patients requiring veno-venous ECMO (VV ECMO). This difficult balance prompted a change in practice at our institution for monitoring intravenous unfractionated heparin (UFH) infusions, from PTT-based UFH titration to anti-Xa-based. This occurred as a gradual shift, providing a means to compare both strategies.
Aims: We aim to determine whether titration of UFH infusion using anti-Xa compared to PTT resulted in fewer heparin titrations and a greater percentage of therapeutic values in patients with COVID-19 infection on VV ECMO.
Methods: Seventeen consecutive COVID-19 patients managed with VV ECMO and UFH were retrospectively reviewed to determine anti-Xa and PTT results and the concurrent UFH target and rate. Rate changes were included if deemed a result of the prior PTT or anti-Xa; changes were excluded if the infusion was changed or stopped for other reasons, including bleeding or discontinuation of ECMO. The therapeutic range was ascertained from the medication order or clinical documentation at the time of a coagulation lab draw, and a determination was made for each PTT or anti-Xa whether the value fell into that range.
Results: Results are shown in Table 1.
Conclusions: In our population of COVID-19 patients on VV ECMO, we observed labile coagulation lab results and frequent UFH infusion rate titrations, with a low percentage of results in therapeutic range whether being monitored by PTT or anti-Xa. In addition to coagulopathy, this may be attributed to narrow goal therapeutic ranges and frequent interruptions of therapy in this population. We did observe a significantly lower mean UFH rate and greater percentage of therapeutic values when targeting anti-Xa compared to PTT, as well as a trend toward fewer UFH titrations.
| PTT | Anti-Xa | P value | |
| Times used for UFH titration – No. (%) | 175 (39%) | 272 (61%) | |
| Mean UFH rate – units/kg/hr (range) | 13.3 (2.5-30.5) | 11.5 (3.4-29.0) | 0.002 |
| Therapeutic values – No. (%) | 69/169 (41%) | 151/251 (60%) | 0.000 |
| UFH rate change in response to result – No. (%) | 73/162 (45%) | 91/242 (39%) | 0.135 |
[Table 1.]
To cite this abstract in AMA style:
Thoma B, Al-Rawas N, Leong R, McDermott L, Dovidio J, Kopenitz J, Gong J, McKenzie S, Rhoades R. Monitoring Unfractionated Heparin Using PTT Versus Anti-Xa in Veno-venous Extracorporeal Membrane Oxygenation Patients with COVID-19 Infection [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/monitoring-unfractionated-heparin-using-ptt-versus-anti-xa-in-veno-venous-extracorporeal-membrane-oxygenation-patients-with-covid-19-infection/. Accessed November 29, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/monitoring-unfractionated-heparin-using-ptt-versus-anti-xa-in-veno-venous-extracorporeal-membrane-oxygenation-patients-with-covid-19-infection/