| Objective:Pulmonary thromboembolism (PTE) has been thought to be a scarce disease in our country for a long time. But according to the primitive statistic data of partial domestic hospitals and clinical experiences, PTE is not rare, and the incidence tends to be increasing. PTE is caused by deep venous thrombosis (DVT). PTE and DVT are the two different form of venous thromboembolism(VTE). Because the manifestation of PTE is not typical, and its onset is obscure, it's difficult to be diagnosed. It is always been mistaken with others or can't be found, thus leading a high mortality and invalidity rate .We can find that there are so much DVT cases caused by injury ,which in turn leading to PTE, in our clinical and forensic practices. So, it's necessary for both clinical diagnoses and forensic pathological examinations to pay high attention to PTE. So far, there is no one clinical monitoring indicator or detection item which has a 100% sensitivity and specificity. Therefore, it's very important to find a good method diagnosing and treating VTE correctly in the early stage. D-dimer assay, as an early VET screening method, has been approved by international organization. It has a high sensitivity and negative predictive value. But its specificity is poor and its positive predictive value is low. So, it's necessary for us to discuss the clinical value of D-dimer assay acting as a preferred VET screening method. The purpose of our study was to examine the practical utility of D-dimer assay for VET screening in bone injured patients in the early stage, and to discuss some forensic examination-related problems about sudden death caused by PTE in injured patients.Method:Patients sample acquisition; Drawing blood samples and assay D-dimer level by ELISA; Screening deep venous thrombosis by color doppler ultrasonography;Scanning lungs of the patients by spiral CT; Statistic data.Result:1. Among 82 patients, 12 patients developing DVT, 6 of them With PTE, 2 of them died.2.The sensitivity of D-dimer assay is 100% and its specificity is 37%, negative predictive value 100%.3.The blood level of D-dimer reaches top at hours 24, and begins to decrease at hours 48. 4.There are significant differences between patients with and without VTE. Within 48 hours after injury, there are not significant differences between patients with and without VTE. But then, the D-dimer level in VTE patients is much higher than those without VTE.5.VET has a close relationship with average D-dimer levels at hours 72, 96, 120, 144.6.There is a positive correlation between ages and the average D-dimer levels(P<0.05).7.There is no significant differences between injured and surgery patients when detecting D-dimer levels at different stages(P>0.05). So does the incidence (P>0.05).Discussion:In our study, D-dimer levels were sampled via an enzyme immunoassay method. It has some virtues, such as high sensitivity and negative predictive value. It would not be interfered by bilirubin, hemoglobin, frozen and thawing. There is no radioactive harm.The 82 patients had a total 656 D-dimer levels. True-negative D-dimer results as a function of time from injury are: 0 hours, 19.5%; 12 hours, 17.1%; 24 hours, 22%; 48 hours, 36.6%; 72 hours, 34.1%; 96 hours, 31.7%; 120 hours, 31.7%; 144 hours, 31.7%. Twelve(14%) had DVT. Six of them(7%) developed PTE, two of them(2.4%) died. None had a false-negative result in trauma patients. The negative predictive value and sensitivity of D-dimer assay is 100%. Because of the high false-positive rate in injured patients with VTE, the value of D-dimer assay lies in its negative predictive value excluding VTE. It was concluded that the blood level of D-dimer reaches top at hours 24, and begins to decrease at hours 48, which can reflect the changes of cross-linked fibrin in our body indirectly. Within the first 48 hours, there was no significant difference between those patients with VTE and those without. But then, the D-dimer level in VTE patients is much higher than those without VTE.VET has a close relationship with average D-dimer levels at hours 72, 96, 120, 144. The D-dimer levels changed now and then, and the development of VTE was progressive too. So, 48 hours latter after injury, persistent positive D-dimer levels assay has an important diagnostic value for VTE.In our study, we found that most bone injury patients had a positive D-dimer level assay, and the degree to which their D-dimer levels were positive was directly proportional to their age. Within the first 48 hours, only 36% patients had a negative D-dimer level assay. The reason for negative result is unknown.There is no significant difference between injured and surgery patients when detecting D-dimer levels at different stages. So does the incidence (P>0.05). Injury can results in breaks in the vascular integrity, which promotes the formation of cross-linked fibrin. And then causes the formation of D-dimer. Surgery is also one form of injury. So, the early diagnostic value of D-dimer for bone injured patients can also be applied to surgery patients.We can also use the high sensitivity virtue and negative predictive value to analysis the cause of sudden death which involving in PTE. If D-dimer level assay was negative, we should try to find other cause. If D-dimer level assay was positive, it suggested that there may be thrombus or other diseases which can also cause increasing of D-dimer level, such as tumor, heart illness in the individual's body. If there are injuries simultaneously, we should think them carefully to assay the participation degree of injury correctly.Conclusion:48 hours after bone injured, persistent positive D-dimer levels assay has an important diagnostic value for VTE. During this time, all patients with negative D-dimer levels assay didn't develop VTE. The high sensitivity and 100% negative predictive value can be used to exclude VTE. The degree to which the patients'D-dimer levels were positive was directly proportional to their age. There is no significant difference between injured and surgery patients when detecting D-dimer levels at different stages. So does the incidence. The purpose of our study was to examine the practical utility of D-dimer assay for VET screening in bone injured patients in the early stage, and to discuss some forensic examination-related problems about sudden death caused by PTE in injured patients.
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