Ultrasound evaluation and risk factors for deep venous thrombosis in the intensive care unit

Introduction

Critically ill patients have a high risk of deep venous thrombosis (DVT); however, data about prevalence and specific risk factors in the ICU are conflicting and the prophylaxis strategies are still debated. The aim of this study is to evaluate the prevalence and risk factors in an ICU dealing with trauma and major surgery patients.

Methods

We analyzed retrospectively data from 142 patients (56 ± 4.8 years) admitted to the ICU from December 2004 to December 2005. We recorded the history, diagnosis, SAPS II, length of stay and major surgery. All patients received standard prophylaxis (LMWH and/or mechanical device). For DVT diagnosis, three compression ultrasound examinations were performed (a) within 48 hours from admission, (b) between the 7th and 10th days, and (c) between the 13th and 16th days. The prevalence of DVT and risk factors were analyzed in the whole population and in the following four groups: ≤ 40 years, 41–59 years, 60–74 years, and ≥ 75 years. Statistics were determined using the Wilcoxon and Mann–Whitney tests and one-way analysis of variance on SPSS; P < 0.5 was considered significant.

Results

One hundred (70%) patients were admitted after trauma, 15 (11%) after surgery, 27 (19%) had medical disease. The mean SAPS II score was 45 ± 15.8 and the mean length of stay was 16 ± 9.84 days. Forty-six patients (32.4%) underwent major surgery following the admission. The overall prevalence of DVT was 17.6% (25/142), with the highest value (24.2%) in the 41–59 year group and the lowest (12.5%) in the >75 year group. DVT was diagnosed in 12/25 (48%) patients within 48 hours from ICU admission and 7/12 (58.3%) had direct venous injury. DVT was diagnosed in the remaining patients after 10 days. We found a strong relationship (P < 0.06) between the length of stay and DVT in patients <40 years. No significant differences were found regarding SAPS.

Conclusion

In our experience, DVT prevalence showed a bimodal occurrence with a first short-term peak, associated with traumatic or surgical direct venous injury, and a medium-term peak, related to an ICU stay >10 days. We therefore oriented the surveillance to the two periods of higher DVT prevalence and we established a training program for the intensivists to improve DVT detection, relieving the workload of the ultrasound physician.