Deep vein thrombosis during prolonged mechanical ventilation despite prophylaxis

Abstract

Objective: To determine the prevalence of deep vein thrombosis (DVT) among patients requiring prolonged mechanical ventilation in the intensive care unit.

Design: Prospective cohort study.

Setting: Medical intensive care unit of a university-affiliated urban teaching hospital.

Patients: Patients requiring mechanical ventilation for >7 days.

Interventions: All patients admitted to the medical intensive care unit requiring prolonged mechanical ventilation underwent duplex ultrasonography of their lower extremities and upper extremities every 7 days. The main outcome identified was the presence of DVT. Secondary outcomes included hospital mortality, hospital and intensive care unit lengths of stay, and the occurrence of pulmonary embolism.

Measurements and main results: A total of 110 patients requiring mechanical ventilation for >7 days were enrolled. Prophylaxis against DVT was employed in 110 of the patients (100%). A total of 26 patients (23.6%) developed DVT. Patients with DVT were statistically more likely to have underlying malignancy (30.8% vs. 8.3%; p =.004) and longer durations of central venous catheterization (26.9 +/- 22.2 days vs. 14.5 +/- 12.1 days; p =.024) compared with patients without DVT. There were no statistically significant differences in hospital mortality or lengths of stay in the hospital and intensive care unit for patients with and without DVT. Patients documented to have DVT by using duplex ultrasonography had a statistically greater frequency of subsequent pulmonary embolism during their hospitalization (11.5% vs. 0.0%; p =.012).

Conclusion: The occurrence of DVT is common among patients requiring prolonged mechanical ventilation in the intensive care unit setting despite the use of prophylaxis measures. These data suggest that alternative strategies for the prevention of DVT should be evaluated. Additionally, early detection methods should be considered to reduce the potential morbidity associated with untreated DVT in this high-risk population.