Deep venous thrombosis in medical-surgical critically ill patients: Prevalence, incidence, and risk factors

Objective: Critically ill patients may be at high risk of venous thromboembolism. The objective was to determine the prevalence, incidence, and risk factors for proximal lower extremity deep venous thrombosis among critically ill medical-surgical patients. Design: Prospective cohort. Setting: Closed university-affiliated intensive care unit. Patients: We enrolled consecutive patients >= 18 yrs of age expected to be in intensive care unit for >= 72 hrs. Exclusion criteria were an admitting diagnosis of trauma, orthopedic surgery, pregnancy, and life support withdrawal. Interventions. Interventions included bilateral lower extremity compression ultrasound within 48 hrs of intensive care unit admission, twice weekly, and if venous thromboembolism was clinically suspected. Thromboprophylaxis was protocol directed and universal. We recorded deep venous thrombosis risk factors at baseline and daily, using multivariate regression analysis to determine independent predictors. Patients were followed to hospital discharge. Results: Among 261 patients with a mean Acute Physiology and Chronic Health Evaluation 11 score of 25.5 (+/- 8.4), the prevalence of deep venous thrombosis was 2.7% (95% confidence interval 1.1-5.5) on intensive care unit admission, and the incidence was 9.6% (95% confidence interval 6.3-13.8) over the intensive care unit stay. We identified four independent risk factors for intensive care unit-acquired deep venous thrombosis: personal or family history of venous thromboembolism (hazard ratio 4.0, 95% confidence interval 1.5-10.3), end-stage renal failure (hazard ratio 3.7, 95% confidence interval 1.2-11.1), platelet transfusion (hazard ratio 3.2, 95% confidence interval 1.2-8.4), and vasopressor use (hazard ratio 2.8, 95% confidence interval 1.1-7.2). Patients with deep venous thrombosis had a longer duration of mechanical ventilation (p = .03), intensive care unit stay (p = .005), and hospitalization (p < .001) than patients without deep venous thrombosis. Conclusions, Despite universal thromboprophylaxis, medicalsurgical critically ill patients remain at risk for lower extremity deep venous thrombosis. Further research is needed to evaluate the risks and benefits of more intense venous thromboembolism prophylaxis.