Thromboprophylaxis in critically ill patients: When? Why? How?

Abstract

The occurrence of venous thromboembolism(VTE) in critically ill patients represents an important cause of increased morbidity and mortality. Because the incidence of VTE in the intensive care unit (ICU) is about 30% without thromboprophylaxis, patients hospitalized in these units should be considered at high risk for thrombosis and should receive a prophylactic treatment. Besides conventional risk factors for VTE (age, cancer, surgery, obesity…), specific factors present in ICU patients may also contribute to VTE, including mechanical ventilation, vasopressors, and central venous lines. Despite these observations, there are few rigorous studies evaluating thromboprophylaxis specifically in the ICU. Low-molecular weight heparins and unfractionated heparin appear effective in preventing VTE. However, the impact of certain clinical characteristics of critically ill patients (oedema, renal insufficiency, or vasopressor) on the risk/benefit of these drugs needs to be clarified. Mechanical devices, elastic stockings, and intermittent pneumatic compression are recommended for critical care patients who are at high risk for bleeding; however, they have never been evaluated in any clinical trial in ICU patients. Further studies are needed to better understand the reasons of VTE occurrence in ICU patients in order to improve management of their thromboprophylaxis.