Objective:To investigate the clinical value of thromboelastogram in early diagnosis of deep vein thrombosis (DVT) in patients undergoing free flap surgery of lower extremity.Methods:A retrospective study was conducted to analyze the 192 patients undergoing surgical repair of soft tissue defects at lower extremity with free anterolateral femoral flap at Department of Orthopaedics, Tongji Hospital from January 2018 to June 2022. There were 117 males and 75 females, with an age of (45.6±12.7) years and an area of skin defects ranging from 5 cm × 3 cm to 18 cm × 9 cm. The patients were divided into 2 groups according to whether DVT occurred on the first day after surgery. In the DVT group of 22 patients, there were 14 males and 8 females, with an age of (47.7±14.3) years; in the DVT-free group of 170 patients, there were 103 males and 67 females, with an age of (45.3±12.5) years. The 2 groups were compared in terms of reaction time, coagulation time, maximum amplitude and coagulation angle in the thromboelastogram. Diagram of receiver operating characteristic (ROC) curves was used to evaluate the predictive value of thromboelastography in assessing the risk of DVT after surgery.Results:The 2 groups were comparable because there was no significant difference in the baseline information or operation time between them ( P>0.05). The reaction time [(5.21±0.85) min] and coagulation time [(1.12±0.30) min] in the DVT group were significantly shorter than those in the DVT-free group [(6.48±0.06) min and (1.60±0.03) min], and the maximum amplitude [(71.45±1.17) mm] and coagulation angle [69.54° (64.59°, 76.64°) ] in the DVT group were significantly larger than those in the DVT-free group [(66.63±0.40) mm and 64.92°(54.11°, 74.21°)] (all P<0.05). The optimal cut-off points in the ROC diagram were 5.46 min at reaction time, 1.52 min at coagulation time, 72.31 mm at maximum amplitude and 59.89° at coagulation angle. The sensitivity and specificity of detecting DVT on the first day after surgery were 80.7% and 71.6%, respectively, according to the combination of the best cut-off points in the ROC diagram and all the indexes in the thromboelastogram. Conclusion:Thromboelastogram is of a great value for the diagnosis of lower extremity DVT, and of a positive significance for the prevention of serious complications after surgery in patients undergoing free flap surgery of lower extremity.

COVID-19 has swept globally and Pakistan is no exception.To investigate the initial introductions and transmissions of the SARS-CoV-2 in Pakistan,we performed the largest genomic epidemiology study of COVID-19 in Pakistan and generated 150 complete SARS-CoV-2 genome sequences from samples collected from March 16 to June 1,2020.We identified a total of 347 mutated positions,31 of which were over-represented in Pakistan.Meanwhile,we found over 1000 intra-host single-nucleotide variants(iSNVs).Several of them occurred concurrently,indicating possible interactions among them or coevolution.Some of the high-frequency iSNVs in Pakistan were not observed in the global population,suggesting strong purifying selections.The genomic epidemiology revealed five distinctive spreading clusters.The largest cluster consisted of 74 viruses which were derived from different geographic locations of Pakistan and formed a deep hierarchical structure,indicating an extensive and persistent nation-wide transmission of the virus that was probably attributed to a signature mutation(G8371T in ORF 1ab)of this cluster.Further-more,28 putative international introductions were identified,several of which are consistent with the epidemiological investigations.In all,this study has inferred the possible pathways of introduc-tions and transmissions of SARS-CoV-2 in Pakistan,which could aid ongoing and future viral surveillance and COVID-19 control.