Study On The Threshold For Sceening Deep Vein Thrombosis By D-Dimer In Lower Limbs Fracture Patients

BACKGROUND:Lower limb venous thrombosis is a common complication in patients with lower limb fractures, due to the high coagulation state after the injury, vein wall damage and blood sluggish. In some cases, the deep vein thrombosis can fall off and lead to a fatal pulmonary embolism (PE), or result in thrombosis Syndrome (Post-thrombotic Syndrome, PTS). So it is extremely necessary to detect the existence of DVT as early as possible and treat it according to the latest guidelines. In the cl inical, D-dimer quantitative>0.5 mg/L is usually used to screen DVT and Doppler ultrasound is used for the final diagnosis as a gold standard.OBJECTIVE:Study on the Relationship between D-dimer trend and lower limb venous thrombosis in lower limb fracture patients. Use ROC curve to find a more practical D-dimer threshold for the patients with lower limb fracture.METHODS:Collect a total number of 44 patients with lower limb fractures, that were accepted in our emergency surgical orthopaedic group for treatment from June,2015 to September,2015. Collect empty stomach blood of each patients in the morning to detect the concentration of plasma D-dimer. Use vascular Doppler ultrasound examination to detect whether a thrombosis exist. All the final data are processed with statistical analysis software SPSS 22.0.RESULTS:43 patients with lower limb fracture, male 33 cases, female 10 cases, DVT 11 cases, average age 45.28 years old. The rate of lower limb fracture with DVT was 25.58%. There is a high risk for patients to form deep venous thrombosis during 2-5 days, or 14-20 days after injury. According to the ROC curve analysis, when we choose D-dimer>1.065 mg/L as a threshold i n the f i rst 3 days, i t can reach sensitivity 78.6%, specificity of 59.6%, AUC 71.2%. And when we choose D-dimer>1.115 mg/L as a threshold in the 3 days later, it can reach sensitivity 70.0%, specificity of 60.8%, AUC 66.8%.Conclusion:For patients with fracture of lower limbs, dynamic D-dimer monitoring is helpful to the early detection of lower limbs venous thrombosis. In patients with lower limbs fracture, it can use the standard that D-dimer>1.065 mg/L as clinical inspect threshold for the first 3 days, and D-dimer>1.115 mg/L for 3 days later. It’s necessary for a patient whose D-dimerover the threshold to make a Doppler ultrasound examination in time. For patients long-term in beds, it should respectively have Doppler ultrasound examination in 14-20 days after injury.