Thromboprophylaxis for Patients in ICU With COVID-19

Overview

The respiratory distress that goes with COVID-19 infection has been related to a procoagulant state, with thrombosis at both venous and arterial levels, that determines hypoxia and tissue dysfunction at several organs. The main sign of this thrombotic activity seems to be the D-Dimers, that have been proposed to identify patients with poor prognosis at an early stage. Knowledge on how to prevent or even treat this procoagulant state is scarce. COVID-19 patients may be out of general thromboprophylaxis recommendations, and recent studies suggest a better prognosis in severe COVID-19 patients receiving anticoagulant therapy with low molecular weight heparin (LMWH). However, the LMWH efficacy and safety, mainly in patients admitted to an Intensive Care Unit, remains to be validated.

Many reports have postulated a procoagulant state along with the respiratory distress caused by coronavirus SARS-CoV2. A complex physiopathology has been proposed trying to explain this profile, mainly based on the thromboinflammatory concept, with thrombosis at both venous and arterial levels. Microvascular thrombi impair the blood flow all over the body, with a vascular shunt due to capillary obstruction, that determines hypoxia and tissue dysfunction at several organs, being the lung the more affected one. Although D-Dimers (DD) are not specific indicators of clot formation, its elevation, in combination with other parameters (hyperfibrinogenemia, mild thrombocytopenia) may suggest a systemic coagulation activation with an increase of thrombin generation and fibrinolysis. In fact, in a retrospective Chinese analysis, a DD higher than 1000 ng/ml was proposed to identify patients with poor prognosis at an early stage. Nevertheless, knowledge on how to prevent or even treat this procoagulant state is scarce. Thromboprophylaxis with low molecular-weight heparin (LMWH) is recommended in most medical patients admitted to the hospital and in nearly all patients in an Intensive Care Unit (ICU). But COVID-19 patients may be out of these recommendations, and some treatment schemes has been proposed, although how to decide the suitable LMWH for each clinical situation is controversial. Recent retrospective studies suggest a better prognosis in severe COVID-19 patients receiving anticoagulant therapy with LMWH. However, the LMWH efficacy and safety, mainly in COVID-19 patients admitted to the ICU, remains to be validated.