Evaluation the Venous Pressure of Deep Vein Thrombosis of Early Phase in Lower Extremity by Ultrasonic Imaging

Abstract

Conventional ultrasound measures the diameter and the velocity of the vein to evaluate early venous tension changes in deep vein thrombosis (DVT) of lower extremity. The accuracy and repeatability of conventional measurement are poor, because diameter measurement of vein are susceptible to not only respiratory and extrusion of edema from soft tissue, but also affected by limit of sampling angle when measuring venous flow rate by the color box. By applying the ratio of common femoral vein and cross-sectional area/cross-sectional perimeter (A/C), DVT early vein tension change was evaluated. The cut-off value method and diagnostic value of the A/C preliminarily was discussed. This study by measuring the value of cross-sectional area, pipe perimeter and their ratio among groups evaluate the value of venous tension change and provide certain reference basis for early clinical intervention. Four-hundred and fifty orthopaedic patients (294 male V.S. 156 female) in our hospital were chosen to perform ultrasound examinations from June 2014 to April 2016, including 150 cases as normal control group, 150 cases as the flow reduced group, 150 cases as venous thrombosis group. Their average age was 36.8±11.0 years (8-67). Inclusion criteria includes that patients had no deep vein blood vessel diseases in lower extremity before. Cross-sectional area (A), cross-sectional perimeter value (C), the ratio of the two and the venous flow velocity of common femoral vein were measured and compared among groups. ROC curve was used to explore the diagnostic value of the A/C. The middle segment of the common femoral vein was selectecd as the measurement point where great saphenous vein enters. The standard of decreasing blood flow velocity was Vmean < 15 cm/s. Quantitative data using one-way ANOVA. P < 0.05 was considered to be statistically significant. For normal control group, the average value of cross-sectional area was 66.13±11.25mm2, the average value of cross-sectional perimeter was 28.84±5.14mm and the average value of A/C was 2.65±0.34. For flow reduced group, the average value of cross-sectional area was 94.82±12.57mm2, the average value of cross-sectional perimeter was 32.49±4.73mm and the average value of A/C was 3.26±0.27. For the venous thrombosis group, the average value of cross-sectional area was 151.63±17.41mm2, the average value of cross-sectional perimeter was 43.62±6.61mm and the average value of A/C was 3.94±0.53. There was significantly differences in the cross-sectional area between the normal control group and flow reduced group and venous thrombosis group (P<0.05). No significant statistical differences was found between flow reduced group and venous thrombosis group. With the development of venous thromboembolism disease gradually increase, A, C, and A/C were found to increase gradually and venous blood flow velocity gradually reduced. The cutoff point value of A/C was 2.91 to evaluate early vein tension change of DVT. The area under ROC curve of ratio of A/C was 0.891, sensitivity was 90.0%, specificity was 77.6%. A/C quantified the variation in vein tension which was used to be an abstract concept. The value of A/C was more stable than the venous diameter and showed relatively small disturbance when assessing the venous tension. We provide new thinking and reference for early intervention of clinical preventing DVT.