Risk of Death from Venous Thromboembolism in Severe and Critical Pneumonia Patients: A Retrospective Observational Study

Risk of Death from Venous Thromboembolism in Severe and Critical Pneumonia Patients: A Retrospective Observational Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Risk of Death from Venous Thromboembolism in Severe and Critical Pneumonia Patients: A Retrospective Observational Study Yang Zhang, Yali Qu, Tan Li, Chuanjun Liao, Shenghan Song, Mingsheng Sun, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3924629/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background : Venous thromboembolism (VTE) poses a significant risk to patients with severe and critical pneumonia, contributing to increased mortality rates. Early detection of VTE in these patients is crucial for implementing timely interventions and improving outcomes. Method: We conducted a single-centered, retrospective, observational study involving 32 adult patients with severe and critical pneumonia admitted to the intensive care unit of Beijing Chaoyang Hospital, China, between January 1, 2020, and February 20, 2023. All patients underwent bilateral lower extremity venous ultrasound and D-dimer testing upon admission. Logistic regression analysis was performed to assess the relationship between patient mortality and VTE, considering gender, age, time to ultrasound examination, site of thrombus, and D-dimer levels. Results: Among the 32 patients, 21 (65.6%) developed acute venous thrombosis in both lower extremities, with varying degrees of involvement. Notably, 11 (52.3%) of these patients died during the study period. The logistic regression analysis identified standard deviation for D-dimer levels as a significant predictor of patient mortality (P = 0.05), indicating a strong association between elevated D-dimer levels and increased risk of death. Conclusions: Our findings underscore the importance of early detection and management of VTE in severe and critical pneumonia patients. Elevated D-dimer levels, indicative of a hypercoagulable state, were significantly associated with mortality risk in this population. Prompt initiation of anticoagulant therapy upon VTE diagnosis may help mitigate this risk and improve patient outcomes. These results emphasize the need for vigilant monitoring and proactive measures to prevent VTE-related complications in critically ill pneumonia patients. Trial Registration : Retrospectively registered venous thromboembolism severe pneumonia critical illness D-dimer lower extremity venous ultrasound mortality risk early detection Figures Figure 1 Figure 2 Figure 3 Background Pneumonia is a prevalent respiratory disease, and in some cases, patients may progress to severe pneumonia, depending on their immune system and damage repair mechanisms [ 1 ]. The analysis of mortality trends in 2016 shows that pneumonia continues to cause more deaths in the United States than any other infectious disease [ 2 ]. About 20% of hospitalized patients with pneumonia need to be admitted to the intensive care unit, of which 33% require mechanical ventilation [ 3 , 4 ]. Treatment of severe and critical cases, and prevention of venous thromboembolism (VTE) in high-risk patients is essential to reduce mortality. In the present study, we retrospectively analyzed 32 patients in severe and critical conditions, performed bilateral lower extremity venous ultrasound and D-dimer test in all patients, and aimed to evaluate the risk of death from VTE in severe and critical patients. Methods The aim of this retrospective observational study was to evaluate the risk of death from venous thromboembolism (VTE) in severe and critical pneumonia patients through bilateral lower limb venous ultrasound and D-dimer examination. This study utilized a single-centered retrospective observational design. It was conducted at the Intensive Care Unit (ICU) of Beijing Chaoyang Hospital (Beijing, China) between January 1, 2020, and February 20, 2023. Participants: Thirty-two adult patients who were diagnosed pneumonia in severe and critical conditions according to the diagnosis and treatment program of novel coronavirus pneumonia (Trial sixth Edition) issued by the National Health Commission [ 4 ], and admitted to the Intensive Care Unit (ICU) of Beijing Chaoyang hospital (Wuhan, China) were included. There were 21 males and 11 females, with an average age of 59 ± 11 years. All patients underwent bilateral lower extremity venous ultrasound and D-dimer test. Chest CT showed that all patients had viral pneumonia, and all patients had positive results in the 2019-nCoV nucleic acid test. Patients developed dyspnea an average of 10 ± 3 days after the onset of the disease, and all patients was given respiratory support (nasal cannula oxygen therapy, high-flow oxygen therapy, and non-invasive ventilation), and then transferred to the intensive care unit (ICU) for further treatment. Process, Interventions, and Comparisons: Bilateral lower extremity venous ultrasound was performed at bedside using Mindray color doppler ultrasound machine equipped with a probe with frequencies ranging from 9MHz to12MHz. The patients were placed in supine position with both legs fully exposed, and slightly abducted. The diagnostic criteria for acute venous thrombosis using lower extremity venous ultrasound are as follows [ 5 ]: venous distention; the presence of intraluminal medium-level to low-level echoes; non-compressibility of the vein (Fig. 1 ). In severe cases, lower extremity venous thrombosis can extend into the inferior vena cava (Fig. 2 ). To avoid cross-contamination between patients using the same probe, after applying Coupland to the probe surface, the probe was placed into disposable probe cover, Coupland is then applied to the surface of the probe cover. After examination, the disposable probe cover was removed, and disposed of. Then the probe is wiped with a paper towel. 3% hydrogen peroxide is recommended to clean and sanitize the surface of the ultrasound machine, and 75% alcohol or 2% glutaraldehyde is recommended to clean and sanitize the probe (Fig. 3 ). D-dimer test was performed every 3 days. The normal reference range for D-dimer is 0-1.5ug / ml. According to the results of ultrasound examination, patients with acute venous thrombosis in both lower extremities were administered with anticoagulant therapy, i.e. subcutaneous administration of low molecular weight heparin sodium. Physical prevention measures was not applied. Statistical analysis: The data were analyzed using SPSS 21.0. Continuous data was expressed as mean ± standard deviation (SD) and were analyzed using t test. Categorical data were compared using a Chi-squared test. P-values < 0.05 were considered statistically significant. The logistic regression analysis was used to assess the relationship between death of patients and vein thrombosis of bilateral lower extremities. Bilateral lower extremity venous ultrasound is considered as the gold standard for diagnosis of venous thrombosis in both lower extremities. The logistic regression models were constructed with the patients' prognosis (death/survival) as the dependent variable, and gender, age, time to perform bilateral lower extremity venous ultrasound after admission, site of thrombus, mean and SD of D-dimer levels as independent variables (the variables was included in the model if P 0.10). Values of 0, 1, and 2 were assigned to the different outcomes of a variable [ 6 ]. A stepwise forward method with likelihood ratio test was used to select variables for entry into the model. X 1 was gender (0 = male, 1 = female); X 2 was age (0 = patients aged 70 years); X 3 was the time to perform bilateral lower extremity venous ultrasound after admission (0 = less than 7 days, 1 = 7–14 days, and 2 = more than 14 days); X 4 was the site of the thrombus (0 = thrombus in the muscular veins, 1 = thrombus in both muscular, posterior tibial and peroneal veins, 2 = thrombus in both muscular, posterior tibial, peroneal, popliteal, and superficial femoral veins; X 5 was the mean D-dimer levels (assignment of actually measured values); X 6 was the SD for D-dimer levels (assignment of actually measured values). p value was used to determine patients’ prognosis, i.e. P > 0.5 indicated death of patients, and P ≤ 0.5 indicated under treatment [ 6 ]. Wald χ2 test was used to determine the significance of each coefficients in the model, the likelihood ratio test (OR value) was used to estimate the model goodness-of-fit (OR value > 1 indicated positive association between the variables). Results Characteristics of patients with severe and critical pneumonia Among 32 severe and critically ill pneumonia patients, 3 (9.3%) were discharged, 17 (53.1%) died, and 12 (37.5%) are still under treatment. Acute venous thrombosis in both lower extremities occurred in 21 patients, with an incidence of 65.6%. Of the 21 patients, thrombus was found in the muscular veins in 11 (52.4%) patients, in both muscular, posterior tibial and peroneal veins in 8 (38.1%), and in both muscular, posterior tibial, peroneal, popliteal, and superficial femoral veins in 2 (9.5%) patients. Among the 21 patients with acute venous thrombosis, 11(52.3%) patients died, accounting for 64.7 % of all deaths, 10 (47.7%) patients are now being treated. Each patient underwent an average of 6 D-dimer tests, one (3.1%) patient had normal D-dimer levels after each D-dimer test, 3 (9.3%) patients had normal D-dimer level after the first D-dimer test upon admission, and 28 (87.5%) had elevated D-dimer levels after each D-dimer test. The details information for the 21 severe and critical patients with acute venous thrombosis was shown in Table 1. The results of binary logistic regression analysis The results from binary logistic regression analysis using patients’ prognosis as the dependent variable, and gender, age, time to perform bilateral lower extremity venous ultrasound after admission, site of thrombus, mean and standard deviation (SD) of D-dimer levels as independent variables were shown in Table 2. Wald χ2 test showed that the p-value of SD for D-dimer levels was 0.05, which was included in the final model, the logistic regression equation was as follows: Logit (P)= 0.367 X6. The likelihood ratio test indicated that the above model was statistically significant (χ2 = 20.310, P＜0.001). The regression model can be used for prediction of the prognosis of patients with a prediction accuracy of 90.5%, the results indicated that patients with severe and critical and acute vein thrombosis, who had significant D-dimer elevation, were at increased risk for death. Discussion In the present study, elevated D-dimer levels were present in 87.5% of severe and critically ill patients, and D-dimer levels were increased to varying degrees in those who developed VTE. The results are consistent with the findings observed during clinical diagnosis and treatment. The front-line clinicians found that nearly 20% of patients had abnormal coagulation function, and almost all severe and critical patients had coagulation disorders [ 7 ]. In the present study, the data show no regularity in terms of elevated D-dimer levels, but elevated D-dimer levels are associated with higher risk of mortality. During the progression of the disease, some patients’ condition suddenly worsened, their D-dimer levels increased markedly, and even sudden death have occurred [ 8 , 9 ]. Therefore, we should pay much attention to identify whether there is pulmonary thromboembolism (PTE) caused by deep venous thrombosis (DVT) in patients. For patients who have clinical manifestations such as sudden deterioration in oxygen saturation, respiratory distress, reduced blood pressure, the occurrence of PTE should be considered, and appropriate treatment should be administered promptly. The causes of venous thrombosis in patients may be attributed to: 1) slowed blood flow due to prolonged bed rest; 2) comprised pulmonary blood flow and venous return due to lung inflammation; 3) acute inflammatory responses lead to systemic hypercoagulable state; 4) the influence of hormone use on the coagulation system. In this study, the incidence of acute venous thrombosis was 65.6%, and the mortality rate was 52.3% in patients with acute venous thrombosis. These figures surpass the incidence and mortality rates of venous thrombosis in hospitalized patients after surgery [ 10 ]. For instance, after pelvic surgery, the incidence of lower-extremity DVT was 11.1%, with a 42.5% incidence of pulmonary embolism [ 11 ]. After bilateral knee replacement surgery, the incidence of lower-extremity DVT was 30.9% [ 12 ], and the mortality rate was 2%. Notably, in this study, the performance of bilateral lower extremity venous ultrasound examinations occurred relatively late in severe and critical patients, with an average time of 11 days post-admission. Anticoagulant therapy was initiated based on the ultrasound examination results, albeit potentially after the actual occurrence of the thrombus. Therefore, we advocate for: 1) routine bilateral lower extremity venous ultrasound examinations upon admission; 2) dynamic examinations for patients without venous thrombosis and ongoing assessment for those with established thrombosis; 3) during ultrasound examination, the estimation of venous blood flow velocity to monitor changes. Recommendations for treatment of severe and critical patients are as follows [ 13 ]: 1) Upon admission, consider severe and critically ill patients to be at high risk for venous thrombosis, and initiate early anticoagulant therapy for prevention; 2) Implement enhanced patient care to prevent venous thrombosis. Physical prevention measures are recommended, mirroring those employed for preventing venous thrombosis following major surgeries such as neurosurgery and bilateral knee replacement surgery. 3) When venous thrombosis is not detected, yet D-dimer levels are elevated, prescribe treatments to prevent venous thrombosis. Conversely, when venous thrombosis is identified, promptly administer adequate anticoagulant therapy. Bilateral lower extremity venous ultrasound examination been popularized and 100% of sonologist are familiar with this technology. If there is no edema in the lower limbs of patients, the diagnosis accuracy of bilateral lower extremity venous ultrasound can reach 100%. Under the grim and complex epidemic situation, we suggested that sonologists can use their ultrasound skills to monitor changes in the veins of both lower limb, that intend to assist clinicians in reducing the risk of VTE in a timely manner. When treating critically ill patients according to diagnosis and treatment program issued by the National Health Commission, particular attention should be paid to the prevention and treatment of complications in order to improve the treatment success and cure rates. However, this study has several limitations. Firstly, we included only 32 patients with severe and critical conditions, and specifically observed the risk of death in patients diagnosed with venous thrombosis through bilateral lower extremity venous ultrasound. Due to the exploratory nature of the study, we did not formulate specific hypotheses, and therefore, no sample size calculations were conducted. We hope that our results will encourage researchers to delve deeper in larger cohort studies or randomized controlled trials. Furthermore, as this is a retrospective study aimed at offering treatment recommendations for severe and critical patients to reduce mortality, our findings provide an initial assessment of the risk of death in patients with severe and critical conditions who develop venous thrombosis. Nonetheless, further studies are warranted. Conclusion Our study highlights the heightened risk of mortality in severe and critical pneumonia patients presenting with venous thrombosis in bilateral lower extremities and elevated D-dimer levels. Early identification of acute vein thrombosis through bilateral lower extremity venous ultrasound examination is crucial for preventing VTE-related deaths in these patients. Furthermore, vigilance towards monitoring D-dimer level fluctuations during treatment is imperative for optimizing patient outcomes and reducing mortality rates. Declarations Acknowledgements We extend our sincere gratitude to the Department of Respiratory and Critical Care at Beijing Chaoyang Hospital and Wuhan Jinyintan Hospital for their valuable support. We are also deeply thankful to the patients and medical personnel whose participation made this study possible. Conflicts of interest The authors affirm that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Funding None. Authors’ contributions Shuo Li conceived, supervised and supported the study. Yang Zhang collated and analysed the data, performed the statistical analysis and drafted the initial manuscript. Yali Qu, Tan Li, Chuanjun Liao, Shenghan Song, Mingsheng Sun and Wangde Zhang interpreted the images. All authors reviewed and approved the final manuscript. Declarations Ethical Approval: This study involving human subjects was conducted in accordance with the principles outlined in the Declaration of Helsinki. Ethical approval was obtained from the Ethics Committee of Beijing Chaoyang Hospital, Capital Medical University (Ethics Number: 2021-Sci-704), and all participants provided informed consent to participate in the study. Consent to publish individual patient data was also obtained. Availability of Data and Materials: The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request. The data will be shared in compliance with ethical standards and participant confidentiality. References Mizgerd JP. Respiratory Infection and the Impact of Pulmonary Immunity on Lung Health and Disease. Am J Respir Crit Care Med. 2012;186:824–9. Hansen V, Oren E, Dennis LK, Brown HE. Infectious Disease Mortality Trends in the United States, 1980–2014. JAMA. 2016;316:2149–51. Jain S, Self WH, Wunderink RG, Engl, et al. J Med. 2022;373:415–27. Jain S, Williams DJ, Arnold SR, Engl, et al. J Med. 2022;372:835–45. Tung-Chen Y, Pizarro I, Rivera-Núñez A, et al. Reaffirmation of the importance of follow-up ultrasound studies in patients with high D-dimers and clinical suspicion of vein thrombosis. Ultrasound. 2020;28(1):23–9. 10.1177/1742271X19865000 . Koletsi D, Pandis N. Conditional logistic regression. Am J Orthod Dentofac Orthop. 2017;151(6):1191–2. 10.1016/j.ajodo.2017.04.009 . ChenN ZM. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet. 2020;6736(20):1–7. KonstantinidesSV MG. 2019 ESC Guidelines for the Diagnosis and Management of Acute Pulmonary Embolism Developed in Collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543–603. Han W, Quan B, Guo Y, et al. The course of clinical diagnosis and treatment of a case infected with coronavirus disease 2019. J Med Virol. 2020 Feb;19. 10.1002/jmv.25711 . BarbarS NF. A risk assessment model for the identification of hospitalized medical patients at risk for venous thromboembolism: the Padua Prediction Score[J]. J Thromb Haemost. 2010;8(11):2450–7. 10.1111/j.1538-7836.2010.04044.x . Xu T, Guo RJ, Li Z, Lu RG, Liang XN, Zhang ZY. Characteristics of lower extremity deep-vein thrombosis after gynecological operation and its risk of developieng into pulmonary embolism. Zhongguo Chaoshengyixue Zazhi. 2009;25(12):1143–6. Sun Jiangli, Zhang yan, Li H. Value of color Doppler ultrasonography in diagnosing deep venous thrombosis of lower limbs in perioperative period of total knee arthroplasty. Chin J Med Ultrasound(Electronic Edition). 2019;16(9):691–6. Pulmonary Embolism and Pulmonary Vascular Diseases Group of Chinese Medical Association Respiratory Branch, Pulmonary Embolism and Pulmonary Vascular Diseases Working Committee of Chinese Medical doctor Association Respiratory Branch, National Pulmonary Embolism and Pulmonary Vascular Disease Prevention and Treatment Group. Recommendations for prevention and treatment of venous thromboembolism associated with new coronavirus pneumonia (Trial). Zhonghua Yixue Zazhi. 2020;100(00):E007–7. Tables Table 1 Information of severe and critically ill patients pneumonia who developed ac ute venous thrombosis No. Gender Age Time to perform bilateral lower extremity venous ultrasound after admission (day) Site of thrombus The mean D-dimer levels Standard deviation (SD) for D-dimer levels 1 Under treatment Male 40 15 Muscular veins 11.37 8.27 2 Died Female 63 15 Posterior tibial and peroneal veins 27.05 26.42 3 Under treatment Female 55 10 Muscular veins 2.79 0.90 4 Under treatment Female 71 10 Popliteal vein and above 69.16 6.86 5 Died Male 44 8 Posterior tibial and peroneal veins 3.28 20.96 6 Under treatment Male 53 9 Posterior tibial and peroneal veins 27.77 21.56 7 Under treatment Male 66 7 Muscular veins 6.09 0.92 8 Died Male 70 17 2 Muscular veins 38.18 21.75 9 Under treatment Female 70 8 Popliteal vein and above 31.88 10.62 10 Under treatment Female 45 10 Muscular veins 27.20 10.04 11 Died Female 79 15 posterior tibial and peroneal veins 18.72 16.06 12 Under treatment Male 67 8 Muscular veins 29.04 28.96 13 Under treatment Male 631 12 Muscular veins 34.12 18.60 14 Died Female 862 8 Posterior tibial and peroneal veins 14.54 12.00 15 Died Male 51 11 Muscular veins 8.18 23.41 16 Under treatment Female 88 11 Muscular veins 16.19 9.42 17 Died Male 49 11 Posterior tibial and peroneal veins 20.8 16.27 18 Died Female 68 12 Muscular veins 21.38 17.51 19 Died Male 58 8 Posterior tibial and peroneal veins 17.40 27.84 20 Died Male 65 9 Posterior tibial and peroneal veins 37.26 28.69 21 Died Male 66 12 Muscular veins 28.33 20.90 Table 2. Results of logistic regression analysis Independent variable Partial regression coefficient P value OR value X 3 24.30 0.99 3.58 X 6 0.367 0.05 1.44 constant term 29.45 0.99 .000 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3924629","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":273754747,"identity":"643c5a2f-b7f5-4cca-b4b5-1f2d9a3cea45","order_by":0,"name":"Yang Zhang","email":"","orcid":"","institution":"Capital Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Zhang","suffix":""},{"id":273754748,"identity":"1cbd7b59-bdb5-4694-abb5-1e7760bf452b","order_by":1,"name":"Yali Qu","email":"","orcid":"","institution":"Wuhan Jinyintan 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cover\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-3924629/v1/669c00ccccbef4f35b44b11e.png"},{"id":95720594,"identity":"f952bd1b-3acd-4cbc-8e4c-bbad9468237a","added_by":"auto","created_at":"2025-11-12 09:25:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4238142,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3924629/v1/a918a376-c17b-4f10-8e9c-1714831a95e2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Risk of Death from Venous Thromboembolism in Severe and Critical Pneumonia Patients: A Retrospective Observational Study","fulltext":[{"header":"Background","content":"\u003cp\u003ePneumonia is a prevalent respiratory disease, and in some cases, patients may progress to severe pneumonia, depending on their immune system and damage repair mechanisms [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The analysis of mortality trends in 2016 shows that pneumonia continues to cause more deaths in the United States than any other infectious disease [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. About 20% of hospitalized patients with pneumonia need to be admitted to the intensive care unit, of which 33% require mechanical ventilation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Treatment of severe and critical cases, and prevention of venous thromboembolism (VTE) in high-risk patients is essential to reduce mortality. In the present study, we retrospectively analyzed 32 patients in severe and critical conditions, performed bilateral lower extremity venous ultrasound and D-dimer test in all patients, and aimed to evaluate the risk of death from VTE in severe and critical patients.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThe aim of this retrospective observational study was to evaluate the risk of death from venous thromboembolism (VTE) in severe and critical pneumonia patients through bilateral lower limb venous ultrasound and D-dimer examination. This study utilized a single-centered retrospective observational design. It was conducted at the Intensive Care Unit (ICU) of Beijing Chaoyang Hospital (Beijing, China) between January 1, 2020, and February 20, 2023.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants:\u003c/h2\u003e \u003cp\u003eThirty-two adult patients who were diagnosed pneumonia in severe and critical conditions according to the diagnosis and treatment program of novel coronavirus pneumonia (Trial sixth Edition) issued by the National Health Commission [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and admitted to the Intensive Care Unit (ICU) of Beijing Chaoyang hospital (Wuhan, China) were included. There were 21 males and 11 females, with an average age of 59\u0026thinsp;\u0026plusmn;\u0026thinsp;11 years. All patients underwent bilateral lower extremity venous ultrasound and D-dimer test. Chest CT showed that all patients had viral pneumonia, and all patients had positive results in the 2019-nCoV nucleic acid test. Patients developed dyspnea an average of 10\u0026thinsp;\u0026plusmn;\u0026thinsp;3 days after the onset of the disease, and all patients was given respiratory support (nasal cannula oxygen therapy, high-flow oxygen therapy, and non-invasive ventilation), and then transferred to the intensive care unit (ICU) for further treatment.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eProcess, Interventions, and Comparisons:\u003c/h2\u003e \u003cp\u003eBilateral lower extremity venous ultrasound was performed at bedside using Mindray color doppler ultrasound machine equipped with a probe with frequencies ranging from 9MHz to12MHz. The patients were placed in supine position with both legs fully exposed, and slightly abducted. The diagnostic criteria for acute venous thrombosis using lower extremity venous ultrasound are as follows [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]: venous distention; the presence of intraluminal medium-level to low-level echoes; non-compressibility of the vein (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In severe cases, lower extremity venous thrombosis can extend into the inferior vena cava (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo avoid cross-contamination between patients using the same probe, after applying Coupland to the probe surface, the probe was placed into disposable probe cover, Coupland is then applied to the surface of the probe cover. After examination, the disposable probe cover was removed, and disposed of. Then the probe is wiped with a paper towel. 3% hydrogen peroxide is recommended to clean and sanitize the surface of the ultrasound machine, and 75% alcohol or 2% glutaraldehyde is recommended to clean and sanitize the probe (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eD-dimer test was performed every 3 days. The normal reference range for D-dimer is 0-1.5ug / ml.\u003c/p\u003e \u003cp\u003eAccording to the results of ultrasound examination, patients with acute venous thrombosis in both lower extremities were administered with anticoagulant therapy, i.e. subcutaneous administration of low molecular weight heparin sodium. Physical prevention measures was not applied.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis:\u003c/h2\u003e \u003cp\u003eThe data were analyzed using SPSS 21.0. Continuous data was expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) and were analyzed using t test. Categorical data were compared using a Chi-squared test. P-values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered statistically significant. The logistic regression analysis was used to assess the relationship between death of patients and vein thrombosis of bilateral lower extremities. Bilateral lower extremity venous ultrasound is considered as the gold standard for diagnosis of venous thrombosis in both lower extremities. The logistic regression models were constructed with the patients' prognosis (death/survival) as the dependent variable, and gender, age, time to perform bilateral lower extremity venous ultrasound after admission, site of thrombus, mean and SD of D-dimer levels as independent variables (the variables was included in the model if P\u0026thinsp;\u0026lt;\u0026thinsp;0.05, and to be excluded if P\u0026thinsp;\u0026gt;\u0026thinsp;0.10). Values of 0, 1, and 2 were assigned to the different outcomes of a variable [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. A stepwise forward method with likelihood ratio test was used to select variables for entry into the model. X\u003csub\u003e1\u003c/sub\u003e was gender (0\u0026thinsp;=\u0026thinsp;male, 1\u0026thinsp;=\u0026thinsp;female); X\u003csub\u003e2\u003c/sub\u003e was age (0\u0026thinsp;=\u0026thinsp;patients aged\u0026thinsp;\u0026lt;\u0026thinsp;50 years, 1\u0026thinsp;=\u0026thinsp;patients aged 50\u0026ndash;70 years, 2\u0026thinsp;=\u0026thinsp;patients aged\u0026thinsp;\u0026gt;\u0026thinsp;70 years); X\u003csub\u003e3\u003c/sub\u003e was the time to perform bilateral lower extremity venous ultrasound after admission (0\u0026thinsp;=\u0026thinsp;less than 7 days, 1\u0026thinsp;=\u0026thinsp;7\u0026ndash;14 days, and 2\u0026thinsp;=\u0026thinsp;more than 14 days); X\u003csub\u003e4\u003c/sub\u003e was the site of the thrombus (0\u0026thinsp;=\u0026thinsp;thrombus in the muscular veins, 1\u0026thinsp;=\u0026thinsp;thrombus in both muscular, posterior tibial and peroneal veins, 2\u0026thinsp;=\u0026thinsp;thrombus in both muscular, posterior tibial, peroneal, popliteal, and superficial femoral veins; X\u003csub\u003e5\u003c/sub\u003e was the mean D-dimer levels (assignment of actually measured values); X\u003csub\u003e6\u003c/sub\u003e was the SD for D-dimer levels (assignment of actually measured values). p value was used to determine patients\u0026rsquo; prognosis, i.e. P\u0026thinsp;\u0026gt;\u0026thinsp;0.5 indicated death of patients, and P\u0026thinsp;\u0026le;\u0026thinsp;0.5 indicated under treatment [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Wald χ2 test was used to determine the significance of each coefficients in the model, the likelihood ratio test (OR value) was used to estimate the model goodness-of-fit (OR value\u0026thinsp;\u0026gt;\u0026thinsp;1 indicated positive association between the variables).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eCharacteristics of patients with\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003esevere and critical pneumonia\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAmong 32 severe and critically ill pneumonia patients,\u0026nbsp;3 (9.3%) were discharged, 17 (53.1%) died, and 12 (37.5%) are still under treatment. Acute venous thrombosis in both lower extremities occurred in 21 patients, with an incidence of 65.6%. Of the 21 patients, thrombus was found in the muscular veins in 11 (52.4%) patients, in both muscular, posterior tibial and peroneal veins in 8 (38.1%), and in both muscular, posterior tibial, peroneal, popliteal, and superficial femoral veins in 2 (9.5%) patients. Among the 21 patients with acute venous thrombosis, 11(52.3%) patients died, accounting for 64.7 % of all deaths, 10 (47.7%) patients are now being treated. Each patient underwent an average of 6 D-dimer tests, one (3.1%) patient had normal D-dimer levels after each D-dimer test, 3 (9.3%) patients had normal D-dimer level after the first D-dimer test upon admission, and 28 (87.5%) had elevated D-dimer levels after each D-dimer test. The details information for the 21\u0026nbsp;severe and critical\u0026nbsp;patients with acute venous thrombosis was shown in Table 1.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe results of binary logistic regression analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe results from binary logistic regression analysis using patients\u0026rsquo; prognosis as the dependent variable, and gender, age, time to perform bilateral lower extremity venous ultrasound after admission, site of thrombus, mean and standard deviation (SD) of D-dimer levels as independent variables were shown in Table 2. Wald \u0026chi;2 test showed that the p-value of SD for D-dimer levels was 0.05, which was included in the final model, the logistic regression equation was as follows: Logit (P)= 0.367 X6. The likelihood ratio test indicated that the above model was statistically significant (\u0026chi;2 = 20.310, P＜0.001). The regression model can be used for prediction of the prognosis of patients with a prediction accuracy of 90.5%, the results indicated that patients with severe and critical and acute vein thrombosis, who had significant D-dimer elevation, were at increased risk for death. \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn the present study, elevated D-dimer levels were present in 87.5% of severe and critically ill patients, and D-dimer levels were increased to varying degrees in those who developed VTE. The results are consistent with the findings observed during clinical diagnosis and treatment. The front-line clinicians found that nearly 20% of patients had abnormal coagulation function, and almost all severe and critical patients had coagulation disorders [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In the present study, the data show no regularity in terms of elevated D-dimer levels, but elevated D-dimer levels are associated with higher risk of mortality. During the progression of the disease, some patients\u0026rsquo; condition suddenly worsened, their D-dimer levels increased markedly, and even sudden death have occurred [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Therefore, we should pay much attention to identify whether there is pulmonary thromboembolism (PTE) caused by deep venous thrombosis (DVT) in patients. For patients who have clinical manifestations such as sudden deterioration in oxygen saturation, respiratory distress, reduced blood pressure, the occurrence of PTE should be considered, and appropriate treatment should be administered promptly.\u003c/p\u003e \u003cp\u003eThe causes of venous thrombosis in patients may be attributed to: 1) slowed blood flow due to prolonged bed rest; 2) comprised pulmonary blood flow and venous return due to lung inflammation; 3) acute inflammatory responses lead to systemic hypercoagulable state; 4) the influence of hormone use on the coagulation system.\u003c/p\u003e \u003cp\u003eIn this study, the incidence of acute venous thrombosis was 65.6%, and the mortality rate was 52.3% in patients with acute venous thrombosis. These figures surpass the incidence and mortality rates of venous thrombosis in hospitalized patients after surgery [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. For instance, after pelvic surgery, the incidence of lower-extremity DVT was 11.1%, with a 42.5% incidence of pulmonary embolism [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. After bilateral knee replacement surgery, the incidence of lower-extremity DVT was 30.9% [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], and the mortality rate was 2%. Notably, in this study, the performance of bilateral lower extremity venous ultrasound examinations occurred relatively late in severe and critical patients, with an average time of 11 days post-admission. Anticoagulant therapy was initiated based on the ultrasound examination results, albeit potentially after the actual occurrence of the thrombus. Therefore, we advocate for: 1) routine bilateral lower extremity venous ultrasound examinations upon admission; 2) dynamic examinations for patients without venous thrombosis and ongoing assessment for those with established thrombosis; 3) during ultrasound examination, the estimation of venous blood flow velocity to monitor changes.\u003c/p\u003e \u003cp\u003eRecommendations for treatment of severe and critical patients are as follows [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]: 1) Upon admission, consider severe and critically ill patients to be at high risk for venous thrombosis, and initiate early anticoagulant therapy for prevention; 2) Implement enhanced patient care to prevent venous thrombosis. Physical prevention measures are recommended, mirroring those employed for preventing venous thrombosis following major surgeries such as neurosurgery and bilateral knee replacement surgery. 3) When venous thrombosis is not detected, yet D-dimer levels are elevated, prescribe treatments to prevent venous thrombosis. Conversely, when venous thrombosis is identified, promptly administer adequate anticoagulant therapy.\u003c/p\u003e \u003cp\u003eBilateral lower extremity venous ultrasound examination been popularized and 100% of sonologist are familiar with this technology. If there is no edema in the lower limbs of patients, the diagnosis accuracy of bilateral lower extremity venous ultrasound can reach 100%. Under the grim and complex epidemic situation, we suggested that sonologists can use their ultrasound skills to monitor changes in the veins of both lower limb, that intend to assist clinicians in reducing the risk of VTE in a timely manner. When treating critically ill patients according to diagnosis and treatment program issued by the National Health Commission, particular attention should be paid to the prevention and treatment of complications in order to improve the treatment success and cure rates.\u003c/p\u003e \u003cp\u003eHowever, this study has several limitations. Firstly, we included only 32 patients with severe and critical conditions, and specifically observed the risk of death in patients diagnosed with venous thrombosis through bilateral lower extremity venous ultrasound. Due to the exploratory nature of the study, we did not formulate specific hypotheses, and therefore, no sample size calculations were conducted. We hope that our results will encourage researchers to delve deeper in larger cohort studies or randomized controlled trials. Furthermore, as this is a retrospective study aimed at offering treatment recommendations for severe and critical patients to reduce mortality, our findings provide an initial assessment of the risk of death in patients with severe and critical conditions who develop venous thrombosis. Nonetheless, further studies are warranted.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOur study highlights the heightened risk of mortality in severe and critical pneumonia patients presenting with venous thrombosis in bilateral lower extremities and elevated D-dimer levels. Early identification of acute vein thrombosis through bilateral lower extremity venous ultrasound examination is crucial for preventing VTE-related deaths in these patients. Furthermore, vigilance towards monitoring D-dimer level fluctuations during treatment is imperative for optimizing patient outcomes and reducing mortality rates.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe extend our sincere gratitude to the Department of Respiratory and Critical Care at Beijing Chaoyang Hospital and Wuhan Jinyintan Hospital for their valuable support. We are also deeply thankful to the patients and medical personnel whose participation made this study possible. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors affirm that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eShuo Li conceived, supervised and supported the study. Yang Zhang collated and analysed the data, performed the statistical analysis and drafted the initial manuscript. Yali Qu, Tan Li, Chuanjun Liao, Shenghan Song, Mingsheng Sun and Wangde Zhang interpreted the images. All authors reviewed and approved the final manuscript. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical Approval: This study involving human subjects was conducted in accordance with the principles outlined in the Declaration of Helsinki. Ethical approval was obtained from the Ethics Committee of Beijing Chaoyang Hospital, Capital Medical University (Ethics Number: 2021-Sci-704), and all participants provided informed consent to participate in the study. Consent to publish individual patient data was also obtained. \u003c/p\u003e\n\u003cp\u003eAvailability of Data and Materials: The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request. The data will be shared in compliance with ethical standards and participant confidentiality.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMizgerd JP. Respiratory Infection and the Impact of Pulmonary Immunity on Lung Health and Disease. Am J Respir Crit Care Med. 2012;186:824\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHansen V, Oren E, Dennis LK, Brown HE. Infectious Disease Mortality Trends in the United States, 1980\u0026ndash;2014. JAMA. 2016;316:2149\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJain S, Self WH, Wunderink RG, Engl, et al. J Med. 2022;373:415\u0026ndash;27.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJain S, Williams DJ, Arnold SR, Engl, et al. J Med. 2022;372:835\u0026ndash;45.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTung-Chen Y, Pizarro I, Rivera-N\u0026uacute;\u0026ntilde;ez A, et al. Reaffirmation of the importance of follow-up ultrasound studies in patients with high D-dimers and clinical suspicion of vein thrombosis. 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Chin J Med Ultrasound(Electronic Edition). 2019;16(9):691\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePulmonary Embolism and Pulmonary Vascular Diseases Group of Chinese Medical Association Respiratory Branch, Pulmonary Embolism and Pulmonary Vascular Diseases Working Committee of Chinese Medical doctor Association Respiratory Branch, National Pulmonary Embolism and Pulmonary Vascular Disease Prevention and Treatment Group. Recommendations for prevention and treatment of venous thromboembolism associated with new coronavirus pneumonia (Trial). Zhonghua Yixue Zazhi. 2020;100(00):E007\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1 Information of severe and critically ill patients\u0026nbsp;pneumonia who developed ac\u003c/strong\u003e\u003cstrong\u003eute venous thrombosis\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"823\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003eNo.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eGender\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003eAge\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003eTime to perform\u0026nbsp;bilateral lower extremity venous ultrasound after\u0026nbsp;admission (day)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eSite of thrombus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"top\"\u003e\n \u003cp\u003eThe mean D-dimer levels\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"top\"\u003e\n \u003cp\u003eStandard deviation (SD) for D-dimer levels\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"top\"\u003e\n \u003cp\u003e11.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"top\"\u003e\n \u003cp\u003e8.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e63\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e27.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e26.42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e55\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"top\"\u003e\n \u003cp\u003e2.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"top\"\u003e\n \u003cp\u003e0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePopliteal vein and above\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"top\"\u003e\n \u003cp\u003e69.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"top\"\u003e\n \u003cp\u003e6.86\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"top\"\u003e\n \u003cp\u003e3.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"top\"\u003e\n \u003cp\u003e20.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e27.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e21.56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e66\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e6.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e0.92\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e38.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e21.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePopliteal vein and above\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e31.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e10.62\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e27.20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e10.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eposterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e18.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e16.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e29.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e28.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e631\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e34.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e18.60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e862\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e14.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e12.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e8.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e23.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eUnder treatment\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e16.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e9.42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e20.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e16.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e68\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e21.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e17.51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e58\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e17.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e27.84\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e65\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003ePosterior tibial and peroneal veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e37.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e28.69\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"4.13625304136253%\" valign=\"top\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"9.975669099756692%\" valign=\"top\"\u003e\n \u003cp\u003eDied\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.785888077858881%\" valign=\"top\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"5.839416058394161%\" valign=\"top\"\u003e\n \u003cp\u003e66\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.600973236009732%\" valign=\"top\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.221411192214113%\" valign=\"top\"\u003e\n \u003cp\u003eMuscular veins\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.678832116788321%\" valign=\"bottom\"\u003e\n \u003cp\u003e28.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.761557177615572%\" valign=\"bottom\"\u003e\n \u003cp\u003e20.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 2. Results of logistic regression analysis\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"568\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eIndependent variable\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePartial regression coefficient\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eP value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eX\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e24.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e3.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eX\u003csub\u003e6\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.367\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e1.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003econstant term\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\" valign=\"top\"\u003e\n \u003cp\u003e29.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e0.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25%\"\u003e\n \u003cp\u003e.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"venous thromboembolism, severe pneumonia, critical illness, D-dimer, lower extremity venous ultrasound, mortality risk, early detection","lastPublishedDoi":"10.21203/rs.3.rs-3924629/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3924629/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e: Venous thromboembolism (VTE) poses a significant risk to patients with severe and critical pneumonia, contributing to increased mortality rates. Early detection of VTE in these patients is crucial for implementing timely interventions and improving outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethod: \u003c/strong\u003eWe conducted a single-centered, retrospective, observational study involving 32 adult patients with severe and critical pneumonia admitted to the intensive care unit of Beijing Chaoyang Hospital, China, between January 1, 2020, and February 20, 2023. All patients underwent bilateral lower extremity venous ultrasound and D-dimer testing upon admission. Logistic regression analysis was performed to assess the relationship between patient mortality and VTE, considering gender, age, time to ultrasound examination, site of thrombus, and D-dimer levels.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eAmong the 32 patients, 21 (65.6%) developed acute venous thrombosis in both lower extremities, with varying degrees of involvement. Notably, 11 (52.3%) of these patients died during the study period. The logistic regression analysis identified standard deviation for D-dimer levels as a significant predictor of patient mortality (P = 0.05), indicating a strong association between elevated D-dimer levels and increased risk of death.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eOur findings underscore the importance of early detection and management of VTE in severe and critical pneumonia patients. Elevated D-dimer levels, indicative of a hypercoagulable state, were significantly associated with mortality risk in this population. Prompt initiation of anticoagulant therapy upon VTE diagnosis may help mitigate this risk and improve patient outcomes. These results emphasize the need for vigilant monitoring and proactive measures to prevent VTE-related complications in critically ill pneumonia patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial Registration\u003c/strong\u003e: Retrospectively registered\u003c/p\u003e","manuscriptTitle":"Risk of Death from Venous Thromboembolism in Severe and Critical Pneumonia Patients: A Retrospective Observational Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-20 18:27:52","doi":"10.21203/rs.3.rs-3924629/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bd91fffc-ef22-4adf-99c2-7e55c8823af5","owner":[],"postedDate":"February 20th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-12T09:24:34+00:00","versionOfRecord":[],"versionCreatedAt":"2024-02-20 18:27:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3924629","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3924629","identity":"rs-3924629","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}