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Background: Prevalence of pulmonary embolism (PE) in patients referred to diagnostic imaging is decreasing, indicating a need for improving patient selection. The aim of this study was to assess reduction in referral to diagnostic imaging by integrating a bespoke ultrasound protocol and describe associated failure rate and adverse events in patients with suspected PE. Methods: In a randomized open-label multicentre trial spanning June 18, 2021, through Feb 1, 2023, adult patients with suspected PE and 1) a Wells score of 0-6 and elevated age-adjusted D-dimer or 2) Wells score >6 were randomly assigned 1:1 to direct diagnostic imaging (controls) or focused lung, cardiac, and deep venous ultrasound by unblinded investigators. Ultrasound could: 1) dismiss PE if no signs of PE and low clinical suspicion or an alternate diagnosis, 2) confirm PE in case of visible venous thrombus, ≥2 subpleural infarctions, McConnell's, or D-sign, or 3) refer to diagnostic imaging if neither category was fulfilled or a patient with confirmed PE by ultrasound required admission. Primary endpoint was proportion of patients referred to diagnostic imaging. Outcome assessors were not blinded to group assignment. All included participants were included in safety analyses. The trial was registered at clinicaltrials.gov (NCT04882579). Findings: A total of 150 patients were recruited, of whom 73 were randomized to ultrasound. Among 77 controls referred to diagnostic imaging, 26 patients had PE confirmed. In the ultrasound group, 40 patients were referred to diagnostic imaging of whom 20 had PE, reducing referral for diagnostic imaging by 45.2% (95% CI: 34.3-56.6, p < 0.0001). Three further PEs were diagnosed by presence of a DVT. During 3-month follow-up, the number of patients who did not receive anticoagulation but was diagnosed with PE was two (4%; 95% CI: 1.1-13.5) and none (0%; 95% CI: 0.0-7.0) in the ultrasound and control group, respectively. Interpretation: Ultrasound substantially reduced referral to diagnostic imaging in suspected PE. Albeit with an unacceptable failure rate. Funding: University of Southern Denmark, Odense University Hospital, Master Carpenter Sophus Jacobsen and wife's foundation, Engineer K. A. Rhode and wife foundation.
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The PIOPED II study provided a robust estimate of the diagnostic accuracy of multidetector CTPA in suspected pulmonary embolism and played a pivotal role in establishing CTPA as the current diagnostic gold standard https://bit.ly/3HEyVxy.
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BACKGROUND: This scoping review was conducted to provide an overview of the evidence of point-of-care lung ultrasound (LUS) in emergency medicine. By emphasizing clinical topics, time trends, study designs, and the scope of the primary outcomes, a map is provided for physicians and researchers to guide their future initiatives. RESEARCH QUESTION: Which study designs and primary outcomes are reported in published studies of LUS in emergency medicine? STUDY DESIGN AND METHODS: We performed a systematic search in the PubMed/MEDLINE, Embase, Web of Science, Scopus, and Cochrane Library databases for LUS studies published prior to May 13, 2023. Study characteristics were synthesized quantitatively. The primary outcomes in all papers were categorized into the hierarchical Fryback and Thornbury levels. RESULTS: A total of 4,076 papers were screened and, following selection and handsearching, 406 papers were included. The number of publications doubled from January 2020 to May 2023 (204 to 406 papers). The study designs were primarily observational (n = 375 [92%]), followed by randomized (n = 18 [4%]) and case series (n = 13 [3%]). The primary outcome measure concerned diagnostic accuracy in 319 papers (79%), diagnostic thinking in 32 (8%), therapeutic changes in 4 (1%), and patient outcomes in 14 (3%). No increase in the proportions of randomized controlled trials or the scope of primary outcome measures was observed with time. A freely available interactive database was created to enable readers to search for any given interest (https://public.tableau.com/app/profile/blinded/viz/LUSinEM_240216/INFO). INTERPRETATION: Observational diagnostic studies have been produced in abundance, leaving a paucity of research exploring clinical utility. Notably, research exploring whether LUS causes changes to clinical decisions is imperative prior to any further research being made into patient benefits.
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Chronic Obstructive Pulmonary Disease (COPD) exacerbation is known for its substantial impact on morbidity and mortality among affected patients, creating a significant healthcare burden worldwide. Coagulation abnormalities have emerged as potential contributors to exacerbation pathogenesis, raising concerns about increased thrombotic events during exacerbation. The aim of this study was to explore the differences in thrombelastography (TEG) parameters and coagulation markers in COPD patients during admission with exacerbation and at a follow-up after discharge. This was a multi-center cohort study. COPD patients were enrolled within 72 h of hospitalization. The baseline assessments were Kaolin-TEG and blood samples. Statistical analysis involved using descriptive statistics; the main analysis was a paired t-test comparing coagulation parameters between exacerbation and follow-up. One hundred patients participated, 66% of whom were female, with a median age of 78.5 years and comorbidities including atrial fibrillation (18%) and essential arterial hypertension (45%), and sixty-five individuals completed a follow-up after discharge. No significant variations were observed in Kaolin-TEG or conventional coagulation markers between exacerbation and follow-up. The Activated Partial Thromboplastin Clotting Time (APTT) results were near-significant, with p = 0.08. In conclusion, TEG parameters displayed no significant alterations between exacerbation and follow-up.
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Pulmonary Disease, Chronic Obstructive , Thrombelastography , Humans , Female , Aged , Male , Thrombelastography/methods , Cohort Studies , Prospective Studies , KaolinABSTRACT
OBJECTIVE: Focused assessment with sonography for trauma (FAST) is a valuable ultrasound procedure in emergency settings, and there is a need for evidence-based education in FAST to ensure competencies. Immersive virtual reality (IVR) is a progressive training modality gaining traction in the field of ultrasound training. IVR holds several economic and practical advantages to the common instructor-led FAST courses using screen-based simulation (SBS). METHODS: This prospective, interventional cohort study investigated whether training FAST using IVR unsupervised and out-of-hospital was non-inferior to a historical control group training at a 90 min SBS course in terms of developing FAST competencies in novices. Competencies were assessed in both groups using the same post-training simulation-based FAST test with validity evidence, and a non-inferiority margin of 2 points was chosen. RESULTS: A total of 27 medical students attended the IVR course, and 27 junior doctors attended the SBS course. The IVR group trained for a median time of 117 min and scored a mean 14.2 ± 2.0 points, compared with a mean 13.7 ± 2.5 points in the SBS group. As the lower bound of the 95% confidence interval at 13.6 was within the range of the non-inferiority margin (11.7-13.7 points), training FAST in IVR for a median of 117 min was found non-inferior to training at a 90 min SBS course. No significant correlation was found between time spent in IVR and test scores. CONCLUSION: Within the limitations of the use of a historical control group, the results suggest that IVR could be an alternative to SBS FAST training and suitable for unsupervised, out-of-hospital courses in basic FAST competencies.
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Focused Assessment with Sonography for Trauma , Virtual Reality , Humans , Cohort Studies , Prospective Studies , Ultrasonography , Clinical CompetenceABSTRACT
Routine clinical application of thoracic ultrasound has greatly enhanced the process of diagnosing and treating patients with pneumothorax and infectious effusion by minimising radiation exposure and facilitating prompt diagnosis https://bit.ly/3FO6jBg.
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Pulmonary embolism is one of the leading causes of death due to cardiovascular disease. Timely diagnosis is crucial, but challenging, as the clinical presentation of pulmonary embolism is unspecific and easily mistaken for other common medical emergencies. Clinical prediction rules and D-dimer measurement allow stratification of patients into groups of expected prevalence and are key elements in adequate selection of patients for diagnostic imaging; however, the strengths and weaknesses of the multiple proposed prediction rules, when to measure D-dimer, and which cutoff to apply might be elusive to a significant proportion of physicians. 13 international guidelines authored by medical societies or expert author groups provide recommendations on facets of the diagnostic investigations in suspected pulmonary embolism, some of which are hallmarked by pronounced heterogeneity. This Review summarises key recommendations of each guideline, considers the most recent evidence on the topic, compares guideline recommendations on each facet of the diagnosis of pulmonary embolism, and provides a synthesis on the most common recommendations.
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Pulmonary Embolism , Humans , Pulmonary Embolism/diagnosis , Fibrin Fibrinogen Degradation Products , Societies, MedicalABSTRACT
Introduction: Thoracic ultrasound (TUS) has proven useful in the diagnosis, risk stratification and monitoring of disease progression in patients with coronavirus disease 2019 (COVID-19). However, utility in follow-up is poorly described. To elucidate this area, we performed TUS as part of a 12-month clinical follow-up in patients previously admitted with COVID-19 and correlated findings with clinical assessment and pulmonary function tests. Methods: Adult patients discharged from our hospital following admission with COVID-19 during March to May 2020 were invited to a 12-month follow-up. Enrolled patients were interviewed regarding persisting or newly developed symptoms in addition to TUS, spirometry and a 6-min walk test. Patients were referred to high-resolution computed tomography (HRCT) of the lungs if suspicion of pulmonary fibrosis was raised. Results: Forty patients were enrolled in the study of whom had 13 developed acute respiratory distress syndrome (ARDS) during admission. Patients with ARDS were more prone to experience neurological symptoms at follow-up (p = 0.03) and showed more B-lines on TUS (p = 0.008) but did not otherwise differ significantly in terms of pulmonary function tests. Four patients had pathological findings on TUS where subsequent diagnostics revealed that two had interstitial lung abnormalities and two had heart failure. These four patients presented with a significantly lower diffusing capacity of lung for carbon monoxide (p=0.03) and 6-min walking distance (p=0.006) compared to the remaining 36 patients without ultrasound pathology. No significant difference was observed in spirometry values of % of predicted FEV1 (p=0.49) or FVC (p=0.07). No persisting cardiovascular pathology was observed in patients without ultrasonographic pathology. Conclusion: At 12-month after admission with COVID-19, a follow-up combining TUS, clinical assessment, and pulmonary function tests may improve the selection of patients requiring further diagnostic investigations such as HRCT or echocardiography.
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BACKGROUND: Serial point-of-care ultrasound (PoCUS) can potentially improve acute patient care through treatment adjusted to the dynamic ultrasound findings. The objective was to investigate if treatment guided by monitoring patients with acute dyspnoea with serial cardiopulmonary PoCUS and usual care could reduce the severity of dyspnoea compared with usual care alone. METHODS: This was a randomised, controlled, blinded-outcome trial conducted in three EDs in Denmark between 9 October 2019 and 26 May 2021. Patients aged ≥18 years admitted with a primary complaint of dyspnoea were allocated 1:1 with block randomisation to usual care, which included a single cardiopulmonary PoCUS within 1 hour of arrival (control group) or usual care (including a PoCUS within 1 hour of arrival) plus two additional PoCUS performed at 2 hours interval from the initial PoCUS (serial ultrasound group). The primary outcome was a reduction of dyspnoea measured on a verbal dyspnoea scale (VDS) from 0 to 10 recorded at inclusion and after 2, 4 and 5 hours. RESULTS: There were 206 patients recruited, 102 in the serial ultrasound group and 104 in the control group, all of whom had complete follow-up. The mean difference in VDS between patients in the serial ultrasound and the control group was -1.09 (95% CI -1.51 to -0.66) and -1.66 (95% CI -2.09 to -1.23) after 4 and 5 hours, respectively. The effect was more pronounced in patients with a presumptive diagnosis of acute heart failure (AHF). A larger proportion of patients received diuretics in the serial ultrasound group. CONCLUSION: Therapy guided by serial cardiopulmonary PoCUS may, together with usual care, facilitate greater improvement in the severity of dyspnoea, especially in patients with AHF compared with usual care with a single PoCUS in the ED. Serial PoCUS should therefore be considered for routine use to aid the physician in stabilising the patient faster. TRIAL REGISTRATION NUMBER: NCT04091334.
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Heart Failure , Point-of-Care Systems , Humans , Adolescent , Adult , Point-of-Care Testing , Heart , Dyspnea/etiology , Heart Failure/complications , Heart Failure/diagnostic imaging , Ultrasonography , Emergency Service, HospitalABSTRACT
BACKGROUND: Patients with lung cancer exhibit increased risk of pulmonary embolism (PE). While the contrast phase of computed tomography of the chest in the diagnostic work-up of suspected chest malignancy does not allow reliable detection of PE, it may be feasible to screen for present PE during endobronchial ultrasound (EBUS) examination. OBJECTIVES: The aim of this study was to establish if screening during EBUS for PE in patients with suspected lung cancer is feasible and if positive findings are predictive of PE. METHODS: Patients undergoing EBUS due to suspicion of malignancy of the chest were prospectively enrolled. The pulmonary arteries were assessed during EBUS using a standardized protocol. Patients in whom PE suspicion was raised were referred to confirmatory imaging. RESULTS: From December 2020 to August 2021, 100 patients were included. Median time for vascular assessment during EBUS was 2 min (Q1-Q3: 1-3 min). EBUS identified two suspected PEs (2%), and the number needed to scan was 50. The positive predictive value of EBUS for PE was 100%. CONCLUSION: EBUS for PE screening seems feasible and with limited time use. The PPV of positive findings for the diagnosis of PE is high, but the utility is somewhat limited by a high number needed to scan even in a high-risk population. Based on our findings, we believe that EBUS assessment of the pulmonary vasculature may have a role as a routine screening tool for PE. The assessment for PE should be implemented in EBUS training programmes, as operators should be able to recognize incidental PEs.
Subject(s)
Bronchi , Early Detection of Cancer , Lung Neoplasms , Pulmonary Edema , Endosonography , Pulmonary Edema/diagnostic imaging , Pulmonary Edema/etiology , Lung Neoplasms/complications , Lung Neoplasms/diagnostic imaging , Humans , Bronchi/diagnostic imaging , Early Detection of Cancer/methods , Male , Female , Middle Aged , AgedABSTRACT
Focused lung ultrasound (FLUS) has high diagnostic accuracy in many common conditions seen in a variety of emergency settings. Competencies are essential for diagnostic success and patient safety but can be challenging to acquire in clinical environments. Immersive virtual reality (IVR) offers an interactive risk-free learning environment and is progressing as an educational tool. First, this study explored the educational impact of novice FLUS users participating in a gamified or non-gamified IVR training module in FLUS by comparing test scores using a test with proven validity evidence. Second, the learning effect was assessed by comparing scores of each group with known test scores of novices, intermediates and experienced users in FLUS. A total of 48 participants were included: 24 received gamified and 24 received non-gamified IVR training. No significant difference was found between gamified (mean = 15.5 points) and non-gamified (mean = 15.2 points), indicating that chosen gamification elements for our setup did not affect learning outcome (p = 0.66). The mean scores of both groups did not significantly differ from those of known intermediate users in FLUS (gamified p = 0.63, non-gamified p = 0.24), indicating that both IVR modules could be used as unsupervised out-of-hospital training for novice trainees in FLUS.
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Education, Medical , Simulation Training , Virtual Reality , Humans , Clinical CompetenceABSTRACT
PURPOSE: The purpose of this descriptive feasibility study was to assess the clinical impact and feasibility of conducting a multiorgan ultrasound examination of patients with pulmonary embolism at both time of diagnosis and at clinical follow-up. METHODS: Hemodynamically stable patients with pulmonary embolism verified by CT pulmonary angiography or ventilation perfusion scintigraphy were eligible for inclusion. Enrolled patients underwent multiorgan ultrasound investigation encompassing echocardiography supplemented with focused lung and deep venous ultrasound emphasizing right ventricular strain, subpleural consolidations and presence of deep venous thrombi. Identical investigations were conducted at 3 months follow-up. The presence of ultrasonographic findings at diagnosis and follow-up was compared and the clinical impact of any remaining pathology or strain was described. RESULTS: Twenty-one patients were enrolled in the study of whom 20 survived to attend follow-up. Mean age was 62 ± 15 years and 48% were female. At diagnosis, the most prevalent ultrasonographic findings were subpleural consolidations in 11 patients and right ventricular dilation in eight. At follow-up, signs of right ventricular strain had resolved in all patients. However, in one patient, no resolution was seen in a subpleural consolidation observed at the time of pulmonary embolism diagnosis, resulting in referral to a chest CT. Additionally, one patient exhibited residual deep venous thrombotic material, leading to prolongation of anticoagulative treatment. CONCLUSION: In patients with pulmonary embolism, multiorgan ultrasound is feasible in follow-up and adequately powered studies should determine the clinical utility of such an approach.
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Pulmonary Embolism , Humans , Female , Middle Aged , Aged , Male , Proof of Concept Study , Pulmonary Embolism/diagnostic imaging , Pulmonary Embolism/therapy , Lung/diagnostic imaging , Echocardiography , UltrasonographyABSTRACT
This study was aimed at comparing the learning efficacy of a traditional instructor-led lesson with that of a completely virtual, self-directed lesson in immersive virtual reality (IVR) in teaching basic point-of-care ultrasound (PoCUS) skills. We conducted a blinded, non-inferiority, parallel-group, randomized controlled trial in which final-year medical students were randomized to an instructor-led (n = 53) or IVR (n = 51) lesson. Participants' learning efficacy was evaluated by blinded assessors, who rated each participant's performance using the Objective Structured Assessment of Ultrasound Skills (OSAUS) assessment tool.The mean total scores for participants were 11.0 points (95% confidence interval: 9.8-12.2) for the instructor-led lesson and 10.3 points (95% confidence interval: 9.0-11.5) for the IVR lesson. No significant differences were observed between the groups with respect to total score (p = 0.36) or subgroup objectives of the OSAUS score (p = 0.34 for familiarity, p = 0.45 for image optimization, p = 0.96 for systematic approach and p = 0.07 for interpretation). Maintenance costs for both courses were estimated at 400 euros each. Startup costs for the instructor-led course were estimated 16 times higher than those for the IVR course. The learning efficacy of an instructor-led lesson on basic US did not differ significantly from that of a self-directed lesson in IVR, as assessed using the OSAUS. The results suggest that IVR could be an equivalent alternative to instructor-led lessons in future basic US courses, but further research is warranted to clarify the role of IVR in PoCUS courses.
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Students, Medical , Virtual Reality , Humans , Clinical Competence , Point-of-Care SystemsABSTRACT
Dyspnoea and chest pain are common causes of referral to emergency departments. Both symptoms are non-specific and may be caused by ST elevation myocardial infarction, aortic dissection, pulmonary embolism, or infection. Fibrin D-dimer is often used for ruling out suspicion of acute diseases, but the clinical utility is limited by a modest specificity which lowers with age to approximately ten per cent at the age of 80 years. This review summarises the recommended approaches and highlights potential pitfalls when utilizing and interpreting fibrin D-dimer in the diagnostic work-up of commonly suspected medical conditions.
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Aortic Dissection , Pulmonary Embolism , Aged, 80 and over , Aortic Dissection/diagnosis , Chest Pain/diagnosis , Chest Pain/etiology , Fibrin Fibrinogen Degradation Products , Humans , Pulmonary Embolism/complications , Pulmonary Embolism/diagnosisABSTRACT
BACKGROUND: Lung cancer is the leading cause of cancer-related death worldwide. Early diagnosis is crucial to increased survival rates. Radial endobronchial ultrasound (rEBUS) and electromagnetic navigation bronchoscopy (ENB) have been developed for the diagnosis of small lung lesions. The aim of this systematic review was to evaluate whether the combination of rEBUS and ENB is superior to ENB alone. METHOD: A systematic search was performed using MEDLINE, Embase, and Cochrane Library databases on "ENB," and conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The project was registered with PROSPERO, number CRD42020214682. RESULTS: In total, 2,092 studies were identified through a literature search. Five studies were included in the final review. One study found that the addition of rEBUS increased diagnostic yield, while another concluded the converse. Three studies did not have significant results. Meta-analysis was not feasible due to heterogeneity and the small number of studies. CONCLUSION: As the current evidence on the topic is sparse and heterogeneous, it is not possible to conclude whether the addition of rEBUS to ENB has a significant impact on diagnostic yield. Further studies are needed to illuminate this question in order to ensure optimal choice of endoscopic technique as well as used time and resources. The project received funding from the Region of Southern Denmark's PhD fund.
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Bronchoscopy , Lung Neoplasms , Bronchoscopy/methods , Electromagnetic Phenomena , Endosonography/methods , Humans , Lung Neoplasms/diagnostic imaging , Lung Neoplasms/pathologyABSTRACT
This article summarises the highlights from the European Respiratory Society's "Clinical techniques, imaging and endoscopy" Assembly 14 presented at the virtual 2021 European Respiratory Society International Congress. Cutting-edge innovative developments in both diagnostic approaches and therapeutic strategies in patients with lung cancer, interstitial lung disease, obstructive airway disorders and infectious diseases were presented on this year's interactive congress platform. In this article, the Assembly 14 subgroups summarise the key take home messages given new research outcomes and place them in the context of the current knowledge.
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Non-tuberculous mycobacteria (NTM) are one of the predominant microbes observed in immunocompromised patients with structural lung disease. Especially in immunocompromised patients, the treating physician needs to be aware of concurrent lung infections with opportunistic pathogens. In this case report we present a man in his 60s with severe chronic obstructive pulmonary disease (COPD) and bullous emphysema, who was diagnosed with Mycobacterium europaeum but with persistent clinical deterioration despite relevant treatment for NTM. A subsequent bronchoalveolar lavage (BAL) revealed elevated Aspergillus galactomannan antigen which, when seen in relation to imaging-findings of cavitating opacities with aggravating surrounding consolidation, raised suspicion of concurrent subacute invasive aspergillosis. Antifungal treatment was initiated but due to intolerable side effects was discontinued after only a few weeks. This case highlights the importance of concurrent testing for pulmonary aspergillosis in NTM patients and vice versa before treatment initiation and if the disease and symptoms are progressing despite relevant treatment.
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Aspergillosis , Pulmonary Aspergillosis , Aspergillosis/diagnosis , Bronchoalveolar Lavage , Humans , Lung/diagnostic imaging , Male , Nontuberculous Mycobacteria , Pulmonary Aspergillosis/diagnosis , Pulmonary Aspergillosis/diagnostic imagingABSTRACT
Contrast-enhanced ultrasound (CEUS) is used in various medical specialties as a diagnostic imaging tool and for procedural guidance. Experience in the procedure is currently attained via supervised clinical practice that is challenged by patient availability and risks. Prior simulation-based training and subsequent assessment could improve and ensure competence before performance on patients, but no simulator currently exists. Immersive virtual reality (IVR) is a new promising simulation tool that can replicate complex interactions and environments that are unfeasible to achieve by traditional simulators. This study was aimed at developing an IVR simulation-based test for core CEUS competencies and gathering validity evidence for the test in accordance with Messick's framework. The test was developed by IVR software specialists and clinical experts in CEUS and medical education and imitated a CEUS examination of a patient with a focal liver lesion with emphasis on the pre-contrast preparations. Twenty-five medical doctors with varying CEUS experience were recruited as test participants, and their results were used to analyze test quality and to establish a pass/fail standard. The final test of 23 test items had good internal reliability (Cronbach's α = 0.85) and discriminatory abilities. The risks of false positives and negatives (9.1% and 23.6%, respectively) were acceptable for the test to be used as a certification tool prior to supervised clinical training in CEUS.
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Simulation Training , Virtual Reality , Clinical Competence , Computer Simulation , Humans , Reproducibility of Results , Simulation Training/methods , UltrasonographySubject(s)
COVID-19 , Aged , COVID-19/diagnostic imaging , Humans , Lung/diagnostic imaging , SARS-CoV-2 , UltrasonographyABSTRACT
OBJECTIVE: To determine the diagnostic accuracy of point-of-care ultrasound in suspected pulmonary embolism. DESIGN: Systematic review and meta-analysis. DATA SOURCES: MEDLINE, Embase, CINAHL and Cochrane library were searched on 2 July 2020 with no restrictions on the date of publication. Subject headings or subheadings combined with text words for the concepts of pulmonary embolism, ultrasound and diagnosis were used. ELIGIBILITY CRITERIA AND DATA ANALYSIS: Eligible studies reported sensitivity and specificity of deep venous, lung, cardiac or multiorgan ultrasound in patients with suspected pulmonary embolism, using an adequate reference-test. Prospective, cross-sectional and retrospective studies were considered for eligibility. No restrictions were made on language. Studies were excluded if a control group consisted of healthy volunteers or if transesophageal or endobronchial ultrasound was used. Risk of bias was assessed using quality assessment of diagnostic accuracy studies-2. Meta-analysis of sensitivity and specificity was performed by construction of hierarchical summary receiver operator curves. I2 was used to assess the study heterogeneity. MAIN OUTCOME MEASURES: The primary outcome was overall sensitivity and specificity of reported ultrasound signs, stratified by organ approach (deep venous, lung, cardiac and multiorgan). Secondary outcomes were stratum-specific sensitivity and specificity within subgroups defined by pretest probability of pulmonary embolism. RESULTS: 6378 references were identified, and 70 studies included. The study population comprised 9664 patients with a prevalence of pulmonary embolism of 39.9% (3852/9664). Risk of bias in at least one domain was found in 98.6% (69/70) of included studies. Most frequently, 72.8% (51/70) of studies reported >24 hours between ultrasound examination and reference test or did not disclose time interval at all. Level of heterogeneity ranged from 0% to 100%. Most notable ultrasound signs were bilateral compression of femoral and popliteal veins (22 studies; 4708 patients; sensitivity 43.7% (36.3% to 51.4%); specificity 96.7% (95.4% to 97.6%)), presence of at least one hypoechoic pleural-based lesion (19 studies; 2134 patients; sensitivity 81.4% (73.2% to 87.5%); specificity 87.4% (80.9% to 91.9%)), D-sign (13 studies; 1579 patients; sensitivity 29.7% (24.6% to 35.4%); specificity 96.2% (93.1% to 98.0%)), visible right ventricular thrombus (5 studies; 995 patients; sensitivity 4.7% (2.7% to 8.1%); specificity 100% (99.0% to 100%)) and McConnell's sign (11 studies; 1480 patients; sensitivity 29.1% (20.0% to 40.1%); specificity 98.6% (96.7% to 99.4%)). CONCLUSION: Several ultrasound signs exhibit a high specificity for pulmonary embolism, suggesting that implementation of ultrasound in the initial assessment of patients with suspected pulmonary embolism may improve the selection of patients for radiation imaging. PROSPERO REGISTRATION NUMBER: CRD42020184313.