Prevention and diagnosis of venous thromboembolism in critically ill patients: a Canadian survey

BACKGROUND: Venous thromboembolism (VTE) confers considerable morbidity and mortality in hospitalized patients, although few studies have focused on the critically ill population. The objective of this study was to understand current approaches to the prevention and diagnosis of deep venous thrombosis (DVT) and pulmonary embolism (PE) among patients in the intensive care unit (ICU). DESIGN: Mailed self-administered survey of ICU Directors in Canadian university affiliated hospitals. RESULTS: Of 29 ICU Directors approached, 29 (100%) participated, representing 44 ICUs and 681 ICU beds across Canada. VTE prophylaxis is primarily determined by individual ICU clinicians (20/29, 69.0%) or with a hematology consultation for challenging patients (9/29, 31.0%). Decisions are usually made on a case-by-case basis (18/29, 62.1%) rather than by preprinted orders (5/29, 17.2%), institutional policies (6/29, 20.7%) or formal practice guidelines (2/29, 6.9%). Unfractionated heparin is the predominant VTE prophylactic strategy (29/29, 100.0%) whereas low molecular weight heparin is used less often, primarily for trauma and orthopedic patients. Use of pneumatic compression devices and thromboembolic stockings is variable. Systematic screening for DVT with lower limb ultrasound once or twice weekly was reported by some ICU Directors (7/29, 24.1%) for specific populations. Ultrasound is the most common diagnostic test for DVT; the reference standard of venography is rarely used. Spiral computed tomography chest scans and ventilation–perfusion scans are used more often than pulmonary angiograms for the diagnosis of PE. ICU Directors recommend further studies in the critically ill population to determine the test properties and risk:benefit ratio of VTE investigations, and the most cost-effective methods of prophylaxis in medical–surgical ICU patients. INTERPRETATION: Unfractionated subcutaneous heparin is the predominant VTE prophylaxis strategy for critically ill patients, although low molecular weight heparin is prescribed for trauma and orthopedic patients. DVT is most often diagnosed by lower limb ultrasound; however, several different tests are used to diagnose PE. Fundamental research in critically ill patients is needed to help make practice evidence-based.