Evaluation of Two-Point Compression Ultrasound as a Screening Tool for Lower Extremity Deep Venous Thrombosis in a Neurocritical Care Unit: Insights from a Single-Center Study

Background Deep venous thrombosis (DVT) is an important cause of morbidity and mortality in the intensive care unit (ICU) and it is often missed in the neurocritical care unit (NCCU) as patients might not manifest with obvious symptomatology. Screening of these patients may provide a preventive benefit. The routine use of formal lower extremity venous Doppler (LEVD) scan, which is done by a vascular laboratory technician and comprises the imaging of the entire lower extremity venous system plus Doppler imaging, can be resource intensive. Alternatively, the two-point compression ultrasound (2-CUS), which consists of the imaging and compression at the common femoral vein and popliteal fossa, is quick and can be done by the clinician at bedside with minimal training. The aim of this study is to evaluate the use of 2-CUS as a screening tool for all patients in the NCCU. Methods We performed a retrospective analysis of prospectively collected data for consecutive patients admitted to the NCCU at Baylor College of Medicine between August 2020 and February 2021. A 2-CUS scan was performed by neurocritical care fellows, evaluating the bilateral common femoral veins and popliteal veins without color Doppler, on admission and every third day. An LEVD scan was performed in all NCCU patients every 7 days and sooner if 2-CUS scan was positive. The inclusion criteria were patients admitted to the neurocritical care service and age ≥18 years. The exclusion criteria were expected length of stay (LOS) of less than 48 hours, known recent DVT, or positive test for COVID-19. Results A total of 298 patients were admitted to the NCCU. 2-CUS was done in 256 patients, while 64 patients underwent both 2-CUS and an LEVD scan. The overall incidence rate of lower extremity DVTs was 10.1%. Nine patients undergoing 2-CUS were positive, of whom six were confirmed by LEVD, and three were false positives (positive predictive value = 66.7%). Two patients had false-negative 2-CUS (negative predictive value = 96.6%). When compared with LEVD, the sensitivity of 2-CUS was 75% (6/8) and the specificity was 95% (57/60). The sensitivity for proximal DVTs was 100%. The two DVTs missed were in the posterior tibial veins not scanned with 2-CUS. Conclusion This is the first study to evaluate the use of 2-CUS as a screening tool for lower extremity DVTs. An incidence of 10.6% was found on patients with a LOS ≥7 days. With a sensitivity of 100% for proximal DVT, a specificity of 95%, and a diagnostic accuracy of 95%, the authors conclude that 2-CUS is a feasible, easily learnt, quick and cost-effective tool for screening DVT in NCCU patients.