Venous thromboembolic disease: an observational study in medical-surgical intensive care unit patients

Acute and chronic illness, immobility, and procedural and pharmacologic interventions may predispose patients in the intensive care unit (ICU) to venous thromboembolic (VTE) disease. The purpose of this study was to observe potential risk factors and diagnostic tests for VTE, and prophylaxis against VTE in medical-surgical ICU patients.

In a prospective observational study, 93 consecutive patients admitted to a mixed medical-surgical ICU were followed. We recorded demographics, admitting diagnoses, APACHE II score, VTE risk factors, antithrombotic, anticoagulant and thrombolytic agents, diagnostic tests for deep venous thrombosis (DVT) and pulmonary embolus (PE), and clinical outcomes.

Patients were 65.5 (15.5) years old with an APACHE II score of 21.1 (9.0); 44 (47.3%) were female. Admission diagnoses were medical (58, 67.4%) and surgical (35, 37.6%). The duration of ICU stay was 3 days (interquartile range: 1, 8.5 days) and the ICU mortality rate was 20.4% (19 of 93). We observed 8 VTE events among 5 of 93 patients (incidence 5.4% [0.8 to 10.0]); 2 patients had DVT and PE before admission, 1 had DVT as an admitting diagnosis, 1 had DVT on day 2 and PE on day 3, and 1 had PE on day 2. Over 804 ICU patient-days, 2 of 5 ultrasound examinations diagnosed DVT and 2 of 3 ventilation-perfusion lung scans diagnosed PE. Of 64 patients in whom heparin was not contraindicated and who were not anticoagulated, subcutaneous heparin prophylaxis was prescribed for 40 (62.5%) patients. ICU-acquired VTE risk factors were mechanical ventilation (odds ratio [OR] 1.56), immobility (OR 2.14), femoral venous catheter (OR 2.24), sedatives (OR 1.52), and paralytic drugs (OR 4.81), whereas VTE heparin prophylaxis (OR 0.08), aspirin (OR 0.42), and thromboembolic disease stockings (OR 0.63) were associated with a lower risk. Only warfarin (OR 0.07, P =.01) and intravenous heparin (OR 0.04, P<.01) were associated with a significantly decreased risk of VTE.

Several ICU-acquired risk factors for VTE were documented in this medical-surgical ICU. VTE prophylaxis was underprescribed, and VTE diagnostic tests were infrequent. Further research is required to determine the incidence, predisposing factors, attributable morbidity, mortality, and costs of VTE in medical-surgical ICU patients, the optimal diagnostic test strategies, and the most cost-effective approaches of prophylaxis.