Objective: To evaluate the diagnostic performance of metagenomic next-generation sequencing (mNGS) using bronchoalveolar lavage fluid (BALF) in patients with ventilator-associated pneumonia (VAP).Methods: BALF samples of 72 patients with VAP were collected from August 2018 to May 2020. The diagnostic performance of conventional testing (CT) and mNGS methods were compared based on bacterial and fungal examinations. The diagnostic value of mNGS for viral and mixed infections was also analyzed.Results: The percentage of mNGS positive samples was significantly higher than that estimated by the CT method [odds ratio (OR), 4.33; 95% confidence interval (CI), 1.78–10.53; p < 0.001]. The sensitivity and specificity of mNGS for bacterial detection were 97.1% (95% CI, 93.2–101.0%) and 42.1% (95 CI, 30.7–53.5%), respectively, whereas the positive predictive value (PPV) and the negative predictive value (NPV) were 60.0% (95% CI, 48.7–71.3%) and 94.1% (95% CI, 88.7–99.6%), respectively. A total of 38 samples were negative for bacterial detection as determined by the CT method, while 22 samples were positive as shown by the mNGS method. Conflicting results were obtained for three samples between the two methods of bacterial detection. However, no significant differences were noted between the mNGS and CT methods (OR, 1.42; 95% CI, 0.68–2.97; p = 0.46) with regard to fungal infections. The sensitivity and specificity of mNGS were 71.9% (95% CI, 61.5–82.3%) and 77.5% (95% CI, 67.9–87.1%), respectively. mNGS exhibited a PPV of 71.9% (95% CI, 61.5–82.3%) and an NPV of 77.5% (95% CI, 67.9–87.1%). A total of 9 out of 40 samples were found positive for fungi according to mNGS, whereas the CT method failed to present positive results in these samples. The mNGS and CT methods produced conflicting results with regard to fungal detection of the two samples. A total of 30 patients were virus-positive using mNGS. Furthermore, 42 patients (58.3%) were identified as pulmonary mixed infection cases.Conclusions: mNGS detection using BALF improved the sensitivity and specificity of bacterial identification in patients who developed VAP. In addition, mNGS exhibited apparent advantages in detecting viruses and identifying mixed infections.

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Background: The PLASMIC score was recently published to aid in the early identification of thrombotic thrombocytopenic purpura (TTP) patients. This study aims to evaluate whether this score is suitable for Chinese suspected TTP patients and find the utility of patients' other characteristics in predicting severe ADAMTS13 deficiency. Methods: We retrospectively studied a Chinese cohort of 38 consecutive hospitalized patients with suspected TTP, ADAMTS13 test results, and other clinical data from September 2016 to May 2018. The predictive power of PLASMIC score in our cohort was evaluated, and patients' other characteristics, especially the high lactate dehydrogenase/the upper limit of normal (LDH/ULN), were studied to determine their distinguishing ability for TTP patients.Results: In this Chinese cohort, 17 patients were diagnosed with TTP according to ADAMTS13 activity results. When dichotomized at intermediate-high risk (scores 5-7) vs low risk (scores 0-4), the PLASMIC score predicted TTP with a sensitivity of 100%, a specificity of 9.52%, and a misdiagnosis rate of 90.48%. And the LDH/ULN alone, or plus platelet count, reticulocyte percentage and indirect bilirubin (IBIL) both had excellent predictive power (area under the curve [AUC] 0.937, 95% confidence interval [CI] 0.863-1.000, P = .000, and AUC 0.994, 95% CI 0.980-1.000, P = .000, respectively). The model including platelet count, reticulocyte percentage, IBIL, and LDH/ULN ratio had a sensitivity of 100%, a specificity of 95.2%, and a misdiagnosis rate of 4.8%.Conclusions: A modified PLASMIC score plus LDH/ULN ratio might be more suitable for identifying ADAMTS13 deficiency patients, especially for making an earlier diagnosis, guiding the immediate and reasonable plasma exchange, and also avoiding unnecessary allocation of plasma. K E Y W O R D SADAMTS13 activity, lactate dehydrogenase, PLASMIC score

Rationale: Catheter-related thrombosis is a serious complication of lung transplantation under venovenous extracorporeal membrane oxygenation (ECMO). Although ECMO-related thrombosis is not uncommon, there are few reports of giant hollow catheter thrombosis in lung transplantation under venovenous ECMO (ECMO). Blood loss and transfusion of coagulation factors may promote ECMO-related thrombosis. Hollow catheter thrombus was not detected on ultrasonography performed after initiation of ECMO. Therefore, it is essential to identify, manage, and reduce or avoid such thrombosis. Patient concerns: We report a rare case of a 43-year-old man with advanced silicosis who developed a massive hollow catheter thrombus during lung transplantation. Anticoagulant therapy did not affect the size of the thrombus. Diagnosis: Giant hollow catheter thrombosis was diagnosed by ultrasonography. Thrombosis from the right external iliac vein to the inferior vena cava was found in the shape of the ECMO pipe. Interventions: Heparin was prescribed as an anticoagulant. Outcomes: Anticoagulant therapy did not affect the size of the thrombus during 2 weeks. The patient developed an infection and died of multiple organ failure. Conclusion: It is uncommon for massive hollow thrombus to occur during venovenous-ECMO-assisted lung transplantation. Fibrinogen and prothrombin complexes promote the formation of thrombus, and the measurement of the wall thickness of ECMO catheter may help to detect such thrombus.