D-dimer testing for suspected pulmonary embolism in outpatients

Altitude-Related Venous Thrombosis With Heart Disease: An Updated Review

Altitude-related venous thrombosis (ARVT) is a condition of growing concern among individuals engaged in high-altitude travel and activities. This updated review explores the epidemiology, pathophysiological mechanisms, clinical presentations, and management of ARVT based on a thematic analysis and synthesis of the existing literature. ARVT's multifactorial etiology involves the interplay of hypobaric hypoxia and endothelial dysfunction, creating a procoagulant state and increasing the risk of thrombosis. Common clinical manifestations include pain, swelling, and redness in the extremities, necessitating accurate and timely diagnosis, particularly in remote settings. Thromboprophylaxis during high-altitude travel and activities plays a crucial role in reducing the risk of ARVT, while anticoagulation remains the mainstay of management. Further research is needed to optimize preventive and treatment strategies, enhancing patient outcomes and safety in high-altitude environments.

Biomarkers and the post-thrombotic syndrome: A systematic review of biomarkers associated with the occurrence of the post-thrombotic syndrome after lower extremity deep venous thrombosis

INTRODUCTION

Post-thrombotic syndrome (PTS) is a frequent chronic complication of deep venous thrombosis (DVT). Biomarkers are potentially valuable clinical tools for handling PTS. The purpose of this review was to examine which biomarkers are associated with the development of PTS in adults with lower extremity DVT.

METHODS

We performed a systematic review of all English language prospective studies of biomarkers and PTS published in PubMed and EMBASE. Studies were included if diagnosing DVT by diagnostic imaging and assessing PTS by clinical scales, for example, the Villalta scale. Biomarkers of thrombophilia and pathological clot properties were not assessed. Data was reported qualitatively.

RESULTS

15 prospective studies were included. Studies varied widely in study design and methods of data analysis. Forty-six different biomarkers were examined, with seven being measured in two or more studies. The most frequently studied biomarkers were D-dimer, CRP, and IL-6. Associations between PTS and D-dimer were predominantly significant, while results on CRP and IL-6 were inconsistent. ICAM-1 was consistently associated with PTS in all studies and at all timepoints. IL-10 was significantly related to PTS development in the largest study and at all time points. Adiponectin, tPA, HRG and TAFI, MMP-1 and -8, and TIMP-1 and -2 were significantly associated with PTS in single studies.

CONCLUSION

(1) Further research on biomarkers and PTS is clearly warranted. (2) Significant differences in study designs made it difficult to draw reliable conclusions regarding individual biomarkers. We suggest the implementation of a standardized framework for the study of biomarkers and PTS, to make comparison of future studies more feasible. (3) D-dimer, ICAM-1, IL-10, MMP-1 and 8, TIMP-1, TIMP-2, and adiponectin are clinical biomarkers of particular interest to include in future studies of PTS. Large scale systemic quantitative proteomic analyses of DVT patients could help identify novel biomarkers of interest in PTS-patients.

Aortic Dissection Detection Risk Score and D-Dimer for Acute Aortic Syndromes in the Chinese Population: Exploration of Optimal Thresholds and Integrated Diagnostic Value

This study aimed to assess the diagnostic performance of the aortic dissection detection risk score (ADD-RS) plus D-dimer for acute aortic syndrome (AAS) in Chinese patients. Two hundred and sixty-two and 200 patients with suspected AAS symptoms were enrolled as exploration cohort and validation cohort, respectively. In exploration cohort, ADD-RS plus D-dimer (AUC = 0.929, 95%CI: 0.887-0.971) presented a better diagnostic value for AAS than ADD-RS or D-dimer alone. Meanwhile, ADD-RS > 1 and D-dimer > 2000 ng/mL were the optimal thresholds. Then, a diagnostic model integrating ADD-RS > 1 plus D-dimer > 2000 ng/mL was established, presenting sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 92.5%, 70.3%, 34.9%, and 98.2%, respectively. In validation cohort, the established diagnostic model exhibited a sensitivity, specificity, PPV, and NPV of 93.1%, 70.2%, 34.6%, and 98.4%, respectively, for diagnosing AAS. Summarily, ADD-RS > 1 and D-dimer > 2000 ng/mL are optimal thresholds for diagnosing AAS in the Chinese population. However, confirmative MSCT results are necessary.

Predictors of pulmonary embolism in hospitalized patients with COVID-19

BACKGROUND

High venous thromboembolism (VTE) rates have been described in critically ill patients with COVID-19. We hypothesized that specific clinical characteristics may help differentiate hypoxic COVID-19 patients with and without a diagnosed pulmonary embolism (PE).

METHODS

We performed a retrospective observational case-control study of 158 consecutive patients hospitalized in one of four Mount Sinai Hospitals with COVID-19 between March 1 and May 8, 2020, who received a Chest CT Pulmonary Angiogram (CTA) to diagnose a PE. We analyzed demographic, clinical, laboratory, radiological, treatment characteristics, and outcomes in COVID-19 patients with and without PE.

RESULTS

92 patients were negative (CTA-), and 66 patients were positive for PE (CTA+). CTA + had a longer time from symptom onset to admission (7 days vs. 4 days, p = 0.05), higher admission biomarkers, notably D-dimer (6.87 vs. 1.59, p < 0.0001), troponin (0.015 vs. 0.01, p = 0.01), and peak D-dimer (9.26 vs. 3.8, p = 0.0008). Predictors of PE included time from symptom onset to admission (OR = 1.11, 95% CI 1.03-1.20, p = 0.008), and PESI score at the time of CTA (OR = 1.02, 95% CI 1.01-1.04, p = 0.008). Predictors of mortality included age (HR 1.13, 95% CI 1.04-1.22, p = 0.006), chronic anticoagulation (13.81, 95% CI 1.24-154, p = 0.03), and admission ferritin (1.001, 95% CI 1-1.001, p = 0.01).

CONCLUSIONS

In 158 hospitalized COVID-19 patients with respiratory failure evaluated for suspected PE, 40.8% patients had a positive CTA. We identified clinical predictors of PE and mortality from PE, which may help with early identification and reduction of PE-related mortality in patients with COVID-19.

A Tale of Two D-Dimers: Comparison of Two Assay Methods to Evaluate Deep Vein Thrombosis or Pulmonary Embolism

BACKGROUND

D-dimer testing rules out deep vein thrombosis (DVT) and pulmonary embolism (PE) in low-risk emergency department (ED) patients. Most research has measured fibrin-equivalent units (FEUs), however, many laboratories measure D-dimer units (DDUs).

OBJECTIVE

Our aim was to determine whether either DDU measurements or FEU measurements can rule out DVT/PE using traditional or age-related cutoff values.

METHODS

We performed a de-identified multicenter retrospective evaluation of D-dimer in nonpregnant adult ED patients to evaluate for DVT/PE. DDUs were multiplied by 2 to determine equivalent FEUs prior to analysis. Sensitivity measurements for D-dimer were calculated for FEUs, DDUs, combined FEU/DDUs, and multiple age-adjusted values.

RESULTS

We identified 47,088 ED patients with a D-dimer laboratory value (27,307 FEUs/19,781 DDUs) and 1623 DVT/PEs. The median combined FEU/DDU D-dimer was 400 ng/mL FEUs (interquartile range [IQR] 300-900 ng/mL FEUs) for patients without a DVT/PE vs 2530 ng/mL FEU (IQR 1094-6000 ng/mL FEUs) with a DVT/PE (p < 0.001), overall sensitivity of 87.3% (95% confidence interval [CI] 87.0-87.6%) and negative predictive value of 99.3% (95% CI 99.2-99.4%). Individually, FEUs performed better than DDUs, with sensitivities of 88.0% (95% CI 85.8-89.9%) and 86.1% (95% CI 83.1-88.7%), respectively; however, this difference was not statistically significant. Combined age-adjusted performance had a sensitivity of 90.3% (95% CI 88.3-92.0%); however, a new DDU-only age-adjusted criteria had the highest sensitivity of 91.1% (95% CI 87.9-93.6%).

CONCLUSIONS

Our undifferentiated D-dimer measurements had a slightly lower sensitivity to rule out DVT/PE than reported previously. Our data support using either DDU or FEU measurements for all ages or when using various age-adjusted criteria to rule out DVT/PE.

Pathophysiology and Management of Pulmonary Embolism

Pulmonary embolism (PE) is one of the most common etiologies of cardiovascular mortality. It could be linked to several risk factors including advanced age. The pathogenesis of PE is dictated by the Virchow's triad that includes venous stasis, endothelial injury, and a hypercoagulable state. The diagnosis of PE is difficult and is often missed due to the nonspecific symptomatology. Hypoxia is common in the setting of PE, and the degree of respiratory compromise is multifactorial and influenced by underlying cardiac function, clot location, and ability to compensate with respiratory mechanics. Right ventricular dysfunction/failure is the more profound cardiovascular impact of acute PE and occurs due to sudden increase in afterload. This is also the primary cause of death in PE. High clinical suspicion is required in those with risk factors and presenting signs or symptoms of venous thromboembolic disease, with validated clinical risk scores such as the Wells, Geneva, and pulmonary embolism rule out criteria in estimating the likelihood for PE. Advancement in capture time and wider availability of computed tomographic pulmonary angiography and D-dimer testing have further facilitated the rapid evaluation and diagnosis of suspected PE. Treatment is dependent on clinical presentation and initially involves providing adequate oxygenation and stabilizing hemodynamics. Anticoagulant therapy is indicated for the treatment of PE. Treatment is guided by presence or absence of shock and ranges from therapeutic anticoagulation to pharmacologic versus mechanical thrombectomy. The prognosis of patients can vary considerably depending on the cardiac and pulmonary status of patient and the size of the embolus.

Investigation of the need for computed tomography pulmonary angiography in the decision to discontinue treatment for pulmonary thromboembolism

BACKGROUND

Acute pulmonary thromboembolism (PTE) is an important cause of morbidity and mortality that can reduce quality of life due to long-term complications during and after treatment discontinuation.

OBJECTIVES

The aim of this study was to evaluate patients for these complications before discontinuing treatment and determine the necessity of computed tomography pulmonary angiography (CTPA) imaging.

METHODS

This retrospective study included 116 patients over the age of 18 who received anticoagulant treatment for at least 3 months and presented for treatment discontinuation to the Atatürk University Research Hospital Chest Diseases Outpatient Clinic between January 2015 and September 2019.

RESULTS

CTPA performed at treatment discontinuation showed complete thrombus resolution with treatment in 73 patients (62.9%). High pulmonary artery obstruction index (PAOI) at diagnosis was statistically associated with findings of residual or chronic thrombus on CTPA at treatment discontinuation (p = 0.001). In the differentiation of patients with residual/chronic thrombus and those with thrombus resolution, D-dimer at a cut-off value of 474 µg/L had 60% sensitivity and 70% specificity. At a cut-off value of 35.5 mmHg, mean pulmonary artery pressure on echocardiography had sensitivity and specificity of 72% and 77%, respectively. At a cut-off of 23.75, PAOI had sensitivity and specificity of 93% and 69%, respectively.

CONCLUSION

In addition to physical examination findings, D-dimer and echocardiography were guiding parameters in the evaluation of treatment discontinuation and thrombus resolution in patients presenting to the outpatient clinic for discontinuation of treatment for acute PTE. PAOI at diagnosis may be another important guiding parameter in addition to these examinations.

Improving Risk Prediction for Pulmonary Embolism in COVID‐19 Patients using Echocardiography

SARS‐CoV‐2 infection is associated with increased risk for pulmonary embolism (PE), a fatal complication that can cause right ventricular (RV) dysfunction. Serum D‐dimer levels are a sensitive test to suggest PE, however lacks specificity in COVID‐19 patients. The goal of this study was to identify a model that better predicts PE diagnosis in hospitalized COVID‐19 patients using clinical, laboratory, and echocardiographic imaging predictors. We performed a cross‐sectional study of 302 adult patients admitted to the Johns Hopkins Hospital (March 2020–February 2021) for COVID‐19 infection who underwent transthoracic echocardiography and D‐dimer testing; 204 patients had CT angiography. Clinical, laboratory and imaging predictors including, but not limited to, D‐dimer and RV dysfunction were used to build prediction models for PE using logistic regression. Model discrimination was assessed using area under the receiver operator curve (AUC) and calibration using Hosmer‐Lemeshow χ² statistic. Internal validation was performed. The prevalence of PE was 7.6%. The model with positive D‐dimer above 5 mg/L, RV dysfunction on echocardiography, and troponin had an AUC of 0.77, and cross‐validated AUC of 0.74. D‐dimer (>5 mg/L) had a positive association with PE (adj odds ratio = 4.40; 95% confidence interval: [1.80, 10.78]). We identified a model including clinical, imaging and laboratory variables that predicted PE in hospitalized COVID‐19 patients. Positive D‐dimer >5, RV dysfunction on echocardiography, and troponin were important predictors for calculating likelihood of PE diagnosis. This approach may be useful to aid in clinical decision‐making related to diagnostic imaging and treatment. Prospective studies are needed to evaluate impact on patient outcomes.

Prevalence of pulmonary embolism in patients with acute exacerbations of COPD: A systematic review and meta-analysis

STUDY OBJECTIVE

Identification of pulmonary embolism (PE) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) carries significant therapeutic implications. We aimed to investigate the prevalence of PE in patients with AECOPD.

METHODS

We searched MEDLINE, the Cochrane Central Register of Controlled Trials, and Embase. We registered the protocol at the PROSPERO (CRD42021230481). Two authors independently evaluated whether titles and abstracts met the eligibility criteria, which were as follows: (1), prospective study or cross-sectional study in case the protocol for workup of PE was specified in advance, (2) patients with AECOPD aged ≥ 18 years, and (3) investigated the prevalence of PE or venous thromboembolism (VTE). Two authors independently extracted the selected patient and study characteristics and outcomes. We presented the results of all analyses with the use of random-effects models. The primary outcome was the prevalence of PE.

RESULTS

We included 16 studies (N = 4093 patients) in this meta-analysis. The prevalence of PE in patients with AECOPD was 12% [95% confidence interval (CI), 9 to 16%]. Substantial heterogeneity was observed (I² = 94.8%). The pooled mortality was higher in patients with PE than those without (odds ratio 5.30, 95%CI: 2.48-11.30, p-value < 0.001).

CONCLUSION

In this meta-analysis, the prevalence of PE in patients with AECOPD was 12% and the mortality of patients with PE was higher than those without. This suggests an acute necessity to develop validated diagnostic strategies for identifying PE in patients with AECOPD.

Serial use of existing clinical decisions aids can reduce computed tomography pulmonary angiography for pulmonary embolism

Pulmonary embolism (PE) remains a diagnostic challenge in emergency medicine. Clinical decision aids (CDAs) like the Pulmonary Embolism Rule-Out Criteria (PERC) are sensitive but poorly specific; serial CDA use may improve specificity. The goal of this before-and-after study was to determine if serial use of existing CDAs in a novel diagnostic algorithm safely decreases the use of CT pulmonary angiograms (CTPA). This was a retrospective before-and-after study conducted at an urban ED with 105,000 annual visits. Our algorithm uses PERC, Wells' score, and D-dimer in series, before moving to CTPA. The algorithm was introduced in January, 2017. Use of CDAs and D-dimer in the 24 months pre- and 12 months post-intervention were obtained by chart review. The algorithm's effect on CTPA ordering was assessed by comparing volume 5 years pre- and 3 years post-intervention, adjusted for ED volume. Mean CTPAs per 1000 adult ED visits was 11.1 in the 5 pre-intervention years and 9.9 in the 3 post-intervention years (p < 0.0001). Use of PERC, Wells' score and D-dimer increased from 1.1%, 1.1%, and 28% to 8.8% (p = 0.0002) 8.1% (p = 0.0005), and 35% (p = 0.0066), respectively. Pre-intervention, there were six potentially missed PEs compared to three in the post-intervention period. Introduction of our serial CDA diagnostic algorithm was associated with increased use of CDAs and D-dimer and reduced CTPA rate without an apparent increase in the number of missed PEs. Prospective validation is needed to confirm these results.

Pulmonary embolism prevalence among emergency department cohorts: A systematic review and meta-analysis by country of study

Essentials The threshold to test for pulmonary embolism (PE) might be lower in North America than Europe. We compared the PE prevalence and positive yield of imaging in Europe and North America. More patients tested in Europe are diagnosed with PE, and imaging is more often positive. Our systematic review supports the hypothesis of overtesting for PE in North America. ABSTRACT: Background There is an impression that North American emergency department (ED) patients tested for pulmonary embolism (PE) differ from European ones. Objectives We compared the PE prevalence, frequency of use, and positive yield of imaging among ED patients tested for PE in Europe and North America. Methods We searched for studies reporting consecutive ED patients tested for PE. Two authors screened full texts, performed risk of bias assessment, and data extraction. We conducted a meta-analysis of proportions for each outcome and a multiple meta-regression. Results From 3109 publications, 44 were included in the systematic review. The prevalence of PE in Europe was 23% (95% confidence interval [CI], 21-26) and in North America 8% (95% CI, 6-9). The adjusted mean difference (aMD) in the prevalence of PE in the European compared with North American studies, was 15% (95% CI, 10-20). Computed tomography pulmonary angiography (CTPA) was used in 60% (95% CI, 52%-68) of European and 38% (95% CI, 24-51) of North American patients tested for PE (aMD, 23% [95% CI, 7-39]). The CTPA diagnostic yield was 29% (95% CI, 26-32) in Europe and 13% (95% CI, 9-17) in North America (aMD, 15% [95% CI, 8-21]). Conclusion Compared with North America, European ED studies have a higher prevalence of PE and diagnostic yield from CTPA, despite a higher frequency of CTPA use among patients tested for PE. This supports the hypothesis that those tested for PE in North American EDs have a lower risk of PE compared with Europe.

An Evidence-based Protocol for Minimizing Thromboembolic Events in SARS-CoV-2 Infection

Coronavirus Disease 2019 (COVID-19) is complicated by significant coagulopathy, that manifests in the form of both pulmonary artery microthromboses and systemic venous thromboembolism (VTE) leading to excess mortality. Dysregulated innate immune response in the lung due to viral-entry mediated angiotensin-I-converting enzyme 2 (ACE2) receptor downregulation causes endothelial injury in the pulmonary vasculature, inflammatory cytokine release, increased thrombin generation and impaired fibrinolysis. The inflammatory disease process, immobilization with prolonged hospital stay, hypoxia due to extensive lung injury and pre-existing comorbidities can contribute to thromboembolic episodes (TE). The observed risk for TE in COVID-19 is high despite anticoagulation, particularly in intensive care unit (ICU) patients. A high level of clinical suspicion, lower threshold for diagnostic imaging and aggressive early and extended thromboprophylaxis is indicated. The available evidence on the optimal strategies to prevent, diagnose, and treat VTE in patients with COVID-19 is heterogenous, but rapidly evolving. We propose an evidence-based, risk-stratified protocol in approaching the risk of TE episodes in COVID-19 patients.

Pulmonary embolism in hospitalised patients with COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19) is characterised by dyspnoea and abnormal coagulation parameters, including raised D-dimer. Data suggests a high incidence of pulmonary embolism (PE) in ventilated patients with COVID-19.

OBJECTIVES

To determine the incidence of PE in hospitalised patients with COVID-19 and the diagnostic yield of Computer Tomography Pulmonary Angiography (CTPA) for PE. We also examined the utility of D-dimer and conventional pre-test probability for diagnosis of PE in COVID-19.

PATIENTS/METHODS

Retrospective review of single-centre data of all CTPA studies in patients with suspected or confirmed COVID-19 identified from Electronic Patient Records (EPR).

RESULTS

There were 1477 patients admitted with COVID-19 and 214 CTPA scans performed, of which n = 180 (84%) were requested outside of critical care. The diagnostic yield for PE was 37%. The overall proportion of PE in patients with COVID-19 was 5.4%. The proportions with Wells score of ≥4 ('PE likely') was 33/134 (25%) without PE vs 20/80 (25%) with PE (P = 0.951). The median National Early Warning-2 (NEWS2) score (illness severity) was 5 (interquartile range [IQR] 3-9) in PE group vs 4 (IQR 2-7) in those without PE (P = 0.133). D-dimer was higher in PE (median 8000 ng/mL; IQR 4665-8000 ng/mL) than non-PE (2060 ng/mL, IQR 1210-4410 ng/mL, P < 0.001). In the 'low probability' group, D-dimer was higher (P < 0.001) in those with PE but had a limited role in excluding PE.

CONCLUSIONS

Even outside of the critical care environment, PE in hospitalised patients with COVID-19 is common. Of note, approaching half of PE events were diagnosed on hospital admission. More data are needed to identify an optimal diagnostic pathway in patients with COVID-19. Randomised controlled trials of intensified thromboprophylaxis are urgently needed.

Quantitative serological antibody testing for suspected neuroborreliosis

OBJECTIVE

To assess the importance of serum IgG/IgM antibody titers for the differentiation of Lyme neuroborreliosis (LNB) from its mimics.

METHOD

This was a retrospective, cross-sectional study conducted at two German neurological centers. Serological parameters (ELISA or CLIA analysis) and clinical presentation of 28 patients with definite LNB were compared to those of 36 patients with neurological symptoms mimicking LNB (mimics). Analysis was performed using receiver operating characteristic (ROC) and binary logistic regression.

RESULTS

Elevated IgG-titers had a high sensitivity for neuroborreliosis in both centers (0.95 and 1.0). The optimal cutoff-values were set to 26.35 in center A (ELISA), and 64.0 in center B (CLIA). Diagnostic specificity was 0.41 and 0.89 in this constellation. Elevated IgM-titers showed a high diagnostic specificity for a cutoff at 68.10 (A) and 47.95 (B) (0.93 and 0.89). Sensitivity was 0.45 and 0.5. Overall diagnostic accuracy was low in both centers (A: IgG AUC = 0.665, IgM AUC = 0.629; B: IgG AUC = 0.917, IgM AUC = 0.556). In logistic regression of antibody titers and clinical measures, prediction of LNB was significantly better than the "null hypothesis". Clinical measures showed the highest odds ratio.

CONCLUSION

Data show that in addition to the clinical presentation of patients with symptoms suggesting central or peripheral nervous system manifestation, serum IgG- and IgM-titers help to identify LNB-patients. The results should guide physicians counseling patients with suspected LNB about further diagnostic steps and treatment.

Lessons in clinical reasoning – pitfalls, myths, and pearls: a case of chest pain and shortness of breath

Background

Defects in human cognition commonly result in clinical reasoning failures that can lead to diagnostic errors. A metacognitive structured reflection on what clinical findings fit and/or do not fit with likely and “can’t miss” diagnoses may reduce such errors.

Case presentation

A 57-year-old man was sent to the emergency department from clinic with chest pain, severe shortness of breath, weakness, and cold sweats. Further investigation revealed multiple risk factors for coronary artery disease, sudden onset of exertional dyspnea, and chest pain that incompletely resolved with rest, mild tachycardia and hypoxia, an abnormal electrocardiogram (ECG), elevated serum cardiac biomarkers, and elevated B-type natriuretic peptide (BNP) in the absence of left-sided heart failure. He was treated for acute coronary syndrome (ACS), discharged, and quickly returned with worsening symptoms that eventually led to a diagnosis of submassive pulmonary embolism (PE).

Conclusions

Through integrated commentary on the diagnostic reasoning process from clinical reasoning experts at two institutions, this case underscores the importance of frequent assessment of fit along with explicit explanation of dissonant features in order to avoid premature closure and diagnostic error. A fishbone diagram is provided to visually demonstrate the major factors that contributed to the diagnostic error. A case discussant describes the importance of diagnostic schema as an analytic reasoning strategy to assist in the creation of a differential diagnosis, problem representation to summarize updated findings, a Popperian analytic approach of attempting to falsify less-likely hypotheses, and matching pertinent positives and negatives to previously learned illness scripts. Finally, this case provides clinical teaching points in addition to a pitfall, myth, and pearl specific to premature closure.

An unmet clinical need: The history of thrombus imaging

Robust thrombus imaging is an unresolved clinical unmet need dating back to the mid 1970s. While early molecular imaging approaches began with nuclear SPECT imaging, contrast agents for virtually all biomedical imaging modalities have been demonstrated in vivo with unique strengths and common weaknesses. Two primary molecular imaging targets have been pursued for thrombus imaging: platelets and fibrin. Some common issues noted over 40 years ago persist today. Acute thrombus is readily imaged with all probes and modalities, but aged thrombus remains a challenge. Similarly, anti-coagulation continues to interfere with and often negate thrombus imaging efficacy, but heparin is clinically required in patients suspected of pulmonary embolism, deep venous thrombosis or coronary ruptured plaque prior to confirmatory diagnostic studies have been executed and interpreted. These fundamental issues can be overcome, but an innovative departure from the prior approaches will be needed.

D-dimer value in the diagnosis of pulmonary embolism-may it exclude only?

Background

Pulmonary embolism (PE) is the third most common cause of death for cardiovascular diseases in Europe. Quick PE diagnosis is therefore crucial for prognosis improvement. It is critical to have suitable screening tests both to exclude PE as well to select patient with highest likelihood of PE occurrence. Currently D-dimer test is accepted as important tool useful to exclude PE in low risk patients. Our goal was to assess the D-dimer test positive prognostic value.

Methods

A retrospective study based on medical record analysis of consecutively admitted patients to 9 wards of The University Clinical Center in Katowice who were hospitalized during four consecutive years was performed. Three hundred and seventy patients met the inclusion criteria for the study, which involved the D-dimer tests and computed tomographic pulmonary angiography (CTPA) performed during hospitalization. Assessed patients were divided into two groups: PE confirmed and PE excluded by CTPA.

Results

We have found that patients with D-dimer levels higher than 2,152 ng/mL had significantly increased risk of PE [area under curve (AUC) of 0.69; 95% CI, 0.64-0.75; P<0.05]. Positive predictive value (PPV) reached the level of 53%, whereas negative predictive value (NPV) reached 82%. We also found that patients with the history of neoplasm and at >65 years of age had D-dimer cut-off point moved to the level of 2,652 ng/mL (AUC of 0.67; 95% CI, 0.52-0.81; P<0.05).

Conclusions

Whereas the NPV of the D-dimer test is generally accepted our results suggest that, in selected cases, an increased plasmatic D-dimer levels may have PPV in PE diagnosis. Patients with the history of neoplasm have higher cut-off D-dimer points above which we should consider increased PE likelihood. CTPA should be considered even for patients with low probability of PE when D-dimer values exceed four times the normal level.

Prognostic value of Mastora obstruction score in acute pulmonary embolism

BACKGROUND

To evaluate the clinical significance of Mastora obstruction score in hemodynamically stable patients with acute pulmonary embolism (aPE).

MATERIALS AND METHODS

One-hundred-and-six patients with newly diagnosed aPE, confirmed by computed tomography pulmonary angiography (CTPA), were included in the study and prospectively examined. aPE severity was assessed by using Mastora obstruction score. According to the Mastora index, patients were divided into "non-massive" and "massive" groups. The  patients' medical histories and blood laboratory data were collected, and instrumental tests were performed and analyzed.

RESULTS

Eighty-two (77%) of the patients had "non-massive" aPE. Cough (48%), fever (44%), and pleural effusion (48%) occurred significantly more often in the  "non-massive" PE group, while syncope (42%) and right ventricular dysfunction (86%) were more frequent in the  "massive" PE group. The  probability of the  right ventricular dysfunction was significantly higher in the  presence of increased pulmonary artery pressure (Cramer's V = 0.410; p < 0.0001) and respiratory failure (Cramer's V = 0.247; p = 0.032). Increased CRP level was found in the majority of the patients (90%). D-dimer level <500 μg/L (lower than the commonly recommended cut-off level) was found in 5% of cases.

CONCLUSIONS

The clinical manifestation depends on the massiveness of aPE. Division of aPE cases into two groups suggests two possible subtypes of aPE: cardiovascular and respiratory. The "non-massive" aPE was associated with respiratory symptoms and an inflammatory response. The  "massive" aPE is associated with an increased D-dimer level and leads to cardiovascular disorders. However, the "massive" aPE may be presented by normal D-dimer concentration level.

Value of D-dimer levels for the diagnosis of pulmonary embolism: An analysis of 32 cases with computed tomography pulmonary angiography

D-dimer levels correlate with the extent of pulmonary embolism (PE) on computed tomography pulmonary angiography (CTPA), but the use of D-dimer alone for screening and diagnosing PE remains controversial. This study compared the utility of plasma D-dimer levels for diagnosing PE with that of CTPA (gold standard). This was a retrospective analysis of 32 consecutive patients with suspected PE at the Affiliated Hospital of Yan'an University between OctoberC 2010 and March 2011. Blood was sampled before thrombolytic therapy was administered. D-dimer levels were measured using an automatic system. CTPA was used to diagnose PE and was performed within 48 h of blood sampling using a Siemens Somatom Sensation 64 computed tomography (CT) scanner. ROC curve analysis was performed to evaluate the diagnostic utility of D-dimer levels, with CTPA as the gold standard. Among the 32 patients, CTPA identified 26 patients with PE and 6 patients without obvious abnormality. Using a threshold value of 1.3 µg/ml for D-dimer level, the diagnosis of PE was achieved with a sensitivity of 96.2%, specificity of 50.0%, positive predictive value of 89.3%, negative predictive value of 75.0% and accuracy of 87.5%. D-dimer levels were significantly higher in patients positive for PE on CTPA than in those negative for PE on CTPA (9.85±7.14 vs. 2.82±2.65 µg/ml, P=0.001). Based on ROC curve analysis, the optimal threshold value for D-dimer level in the diagnosis of PE was 1.9 µg/ml. To conclude, D-dimer could be a simple, fast and inexpensive screening method for excluding a diagnosis of PE.

Likelihood ratios of quantitative laboratory results in medical diagnosis: The application of Bézier curves in ROC analysis

Receiver operating characteristic (ROC) analysis is widely used to describe the discriminatory power of a diagnostic test to differentiate between populations having or not having a specific disease, using a dichotomous threshold. In this way, positive and negative likelihood ratios (LR+ and LR-) can be calculated to be used in Bayes’ way of estimating disease probabilities. Similarly, LRs can be calculated for certain ranges of test results. However, since many diagnostic tests are of quantitative nature, it would be desirable to estimate LRs for each quantitative result. These LRs are equal to the slope of the tangent to the ROC curve at the corresponding point. Since the exact distribution of test results in diseased and non-diseased people is often not known, the calculation of such LRs for quantitative test results is not straightforward. Here, a simple distribution-independent method is described to reach this goal using Bézier curves that are defined by tangents to a curve. The use of such a method would help in standardizing quantitative test results, which are not always comparable between different test providers, by reporting them as LRs for a specific diagnosis, in addition to, or instead of, quantities such as mg/L or nmol/L, or even indices or units.

Incomplete Resolution of Deep Vein Thromboses during Rivaroxaban Therapy

We present the case of a patient with a deep vein thrombosis (DVT) who failed rivaroxaban therapy. Our patient initially presented with left lower extremity edema, erythema, and pain. He was subsequently started on rivaroxaban therapy for a combined treatment period of 12 months, during and after which he persisted to have evidence of a DVT. The patient's prescribed drug regimen was changed from rivaroxaban to warfarin, which demonstrated a rapid resolution of the DVTs as determined by ultrasound assessment of our patient's lower extremity veins. Rivaroxaban, a factor Xa inhibitor, is a well-known oral anticoagulant that is used for a variety of indications and has become a mainstay in the treatment of deep vein thrombosis. With the introduction and emergence of this medication in the clinic, postmarketing reports of efficacy or lack thereof are important to review. In conclusion, we anticipate that it is likely that there are other patients with DVTs who may not respond to rivaroxaban and for whom alternative anticoagulation therapies should be explored.

Accuracy of using serum D-dimer for diagnosis of acute intestinal ischemia: A meta-analysis

OBJECTIVE

The purpose of this meta-analysis is to comprehensively assess the accuracy of serum D-dimer for the diagnosis of acute intestinal ischemia.

METHODS

Diagnostic studies of D-dimer for accurate diagnosis of acute intestinal ischemia were extracted from 6 databases, and prospective and retrospective studies that provided adequate data on sensitivity and specificity were included here. Sensitivity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated. The overall diagnostic performance of D-dimer was assessed by plotting a summary receiver operating characteristic curve (SROC) and calculating the area under the curve (AUC).

RESULTS

A total of 1300 patients with suspected acute intestinal ischemia from 12 studies met the inclusion criteria. The combined sensitivity, specificity, PLR, NLR, and DOR were 0.94 (95% CI: 0.87-0.97), 0.50 (95% CI: 0.40-0.61), 1.9 (95% CI: 1.5-2.3), 0.12 (95% CI: 0.05-0.26), and 16 (95% CI: 7-39), respectively. The AUC was 0.81 (95% CI: 0.78-0.84).

CONCLUSION

The results of this meta-analysis suggested that plasma D-dimer detection might be a useful means of identifying patients with acute intestinal ischemia of the abdomen.

Diagnostic characteristics of lower limb venous compression ultrasonography in suspected pulmonary embolism: a meta-analysis

Essentials Lower limb ultrasonography (CUS) could be useful in suspected pulmonary embolism (PE). We performed a metaanalysis on the diagnostic characteristics of CUS in suspected PE. With a sensitivity of 41%, proximal CUS would be positive in one of every 7.3 patients. Complete CUS has a higher sensitivity but specificity for PE is too low to use it in suspected PE.

SUMMARY

Background Diagnosis of pulmonary embolism (PE) is commonly based on D-dimer measurement and computed tomography (CT) angiography. Lower limb vein compression ultrasonography (CUS) for diagnosing deep vein thrombosis may be of interest in patients with suspected PE. Objectives We aimed to summarize the data on the diagnostic characteristics of CUS in suspected PE patients. Patients/Methods We conducted a literature review by using PUBMED and EMBASE and included 15 prospective studies in which CUS was performed in consecutive patients with suspected PE. Results Of the 6991 included patients, 2001 (30%) had pulmonary embolism. Eight of the 15 studies included only outpatients, two included hospitalized patients and five involved both in- and outpatients. In 13 studies, only proximal CUS was performed. Two studies analyzed the added value of distal CUS including the calf veins (whole-leg CUS). Pooled estimate of proximal CUS sensitivity was 41% (95% confidence interval [CI], 36-46%) with strong heterogeneity (I square, 79%). Specificity of proximal CUS was 96% (95% CI, 94-98%). The overall positive likelihood ratio for proximal CUS was 11.9 (95% CI, 7.1-19.8), whereas the overall negative likelihood ratio was 0.6 (95% CI, 0.5-0.7). The sensitivity of whole-leg CUS was 79% (95% CI, 24-98%) and specificity was 84% (95% CI, 76-90%). Conclusions Proximal CUS has low sensitivity and cannot be used to rule out PE. Nevertheless, its high specificity allows confirming PE, which may be useful in patients with contraindications to CT angiography. Whole-leg CUS has a higher sensitivity but low specificity for PE and can therefore not be recommended.

D-dimer test for excluding the diagnosis of pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) can occur when a thrombus (blood clot) travels through the veins and lodges in the arteries of the lungs, producing an obstruction. People who are thought to be at risk include those with cancer, people who have had a recent surgical procedure or have experienced long periods of immobilisation and women who are pregnant. The clinical presentation can vary, but unexplained respiratory symptoms such as difficulty breathing, chest pain and an increased respiratory rate are common.D-dimers are fragments of protein released into the circulation when a blood clot breaks down as a result of normal body processes or with use of prescribed fibrinolytic medication. The D-dimer test is a laboratory assay currently used to rule out the presence of high D-dimer plasma levels and, by association, venous thromboembolism (VTE). D-dimer tests are rapid, simple and inexpensive and can prevent the high costs associated with expensive diagnostic tests.

OBJECTIVES

To investigate the ability of the D-dimer test to rule out a diagnosis of acute PE in patients treated in hospital outpatient and accident and emergency (A&E) settings who have had a pre-test probability (PTP) of PE determined according to a clinical prediction rule (CPR), by estimating the accuracy of the test according to estimates of sensitivity and specificity. The review focuses on those patients who are not already established on anticoagulation at the time of study recruitment.

SEARCH METHODS

We searched 13 databases from conception until December 2013. We cross-checked the reference lists of relevant studies.

SELECTION CRITERIA

Two review authors independently applied exclusion criteria to full papers and resolved disagreements by discussion.We included cross-sectional studies of D-dimer in which ventilation/perfusion (V/Q) scintigraphy, computerised tomography pulmonary angiography (CTPA), selective pulmonary angiography and magnetic resonance pulmonary angiography (MRPA) were used as the reference standard.•

PARTICIPANTS

Adults who were managed in hospital outpatient and A&E settings and were suspected of acute PE were eligible for inclusion in the review if they had received a pre-test probability score based on a CPR.•

INDEX TESTS

quantitative, semi quantitative and qualitative D-dimer tests.• Target condition: acute symptomatic PE.• Reference standards: We included studies that used pulmonary angiography, V/Q scintigraphy, CTPA and MRPA as reference standard tests.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed quality using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). We resolved disagreements by discussion. Review authors extracted patient-level data when available to populate 2 × 2 contingency tables (true-positives (TPs), true-negatives (TNs), false-positives (FPs) and false-negatives (FNs)).

MAIN RESULTS

We included four studies in the review (n = 1585 patients). None of the studies were at high risk of bias in any of the QUADAS-2 domains, but some uncertainty surrounded the validity of studies in some domains for which the risk of bias was uncertain. D-dimer assays demonstrated high sensitivity in all four studies, but with high levels of false-positive results, especially among those over the age of 65 years. Estimates of sensitivity ranged from 80% to 100%, and estimates of specificity from 23% to 63%.

AUTHORS' CONCLUSIONS

A negative D-dimer test is valuable in ruling out PE in patients who present to the A&E setting with a low PTP. Evidence from one study suggests that this test may have less utility in older populations, but no empirical evidence was available to support an increase in the diagnostic threshold of interpretation of D-dimer results for those over the age of 65 years.

Diagnostic test accuracy of D-dimer for acute aortic syndrome: systematic review and meta-analysis of 22 studies with 5000 subjects

Diagnostic test accuracy of D-dimer for acute aortic dissection (AAD) has not been evaluated by meta-analysis with the bivariate model methodology. Four databases were electrically searched. We included both case-control and cohort studies that could provide sufficient data concerning both sensitivity and specificity of D-dimer for AAD. Non-English language articles and conference abstract were allowed. Intramural hematoma and penetrating aortic ulcer were regarded as AAD. Based on 22 eligible articles consisting of 1140 AAD subjects and 3860 non-AAD subjects, the diagnostic odds ratio was 28.5 (95% CI 17.6-46.3, I(2) = 17.4%) and the area under curve was 0.946 (95% CI 0.903-0.994). Based on 833 AAD subjects and 1994 non-AAD subjects constituting 12 studies that used the cutoff value of 500 ng/ml, the sensitivity was 0.952 (95% CI 0.901-0.978), the specificity was 0.604 (95% CI 0.485-0.712), positive likelihood ratio was 2.4 (95% CI 1.8-3.3), and negative likelihood ratio was 0.079 (95% CI 0.036-0.172). Sensitivity analysis using data of three high-quality studies almost replicated these results. In conclusion, D-dimer has very good overall accuracy. D-dimer <500 ng/ml largely decreases the possibility of AAD. D-dimer >500 ng/ml moderately increases the possibility of AAD.

Retrospective evaluation of shortened prothrombin time or activated partial thromboplastin time for the diagnosis of hypercoagulability in dogs: 25 cases (2006-2011)

OBJECTIVE

To evaluate the relationship between shortened prothrombin time (PT) or activated partial thromboplastin time (aPTT) values, clinical findings associated with hypercoagulability, suspicion of pulmonary thromboembolism (PTE), D-dimer concentrations, and thromboelastogram (TEG) indices.

DESIGN

Retrospective observational study from 2006 to 2011.

SETTING

University veterinary teaching hospital.

ANIMALS

Twenty-three dogs with TEG tracings and shortened PT or aPTT values and 23 control dogs with TEG tracings and normal PT and aPTT values.

MEASUREMENTS AND MAIN RESULTS

Parameters evaluated included signalment, coagulation testing results (PT, aPTT, D-dimer concentration), TEG measurements (R, K, α, maximal amplitude) and calculated clotting index, findings of clinical hypercoagulability (thrombosis of intravenous/intra-arterial catheters, vessel thrombosis, and suspected PTE). Dogs with shortened PT or aPTT had significantly more thrombus formation (P = 0.038), suspicion of PTE (P < 0.001), and increased D-dimer concentration (P < 0.001) compared to dogs with normal PT and aPTT values. There were no significant findings when compared to TEG values.

CONCLUSIONS

A shortened PT or aPTT in dogs may be indicative of a hypercoagulable state as evidenced by an increased incidence of thrombosis, frequency of suspected PTE, and increased circulating D-dimers. A prospective study is warranted to further evaluate the use of PT and aPTT to diagnose hypercoagulable states.

Comparison of multidetector computed tomography findings with clinical and laboratory data in pulmonary thromboembolism

BACKGROUND

Pulmonary thromboembolism (PTE) is a common disease with a high mortality rate that is difficult to diagnose and treat. Because of the variety of clinical symptoms and signs, it is difficult to diagnose. Therefore, the diagnosis of PTE is mainly confirmed by imaging techniques. The aim of this study was to evaluate whether there is any corelation of the Wells rule, D-dimer and LDH values with computerized tomography pulmonary angiography (CTPA) findings in PTE diagnosis.

MATERIAL/METHODS

A consecutive series of 62 patients, which included 31 males and 31 females, with high/moderate/low risk of embolism according to Wells pulmonary embolism score, selected from the emergency service and/or outpatient clinic, enrolled in this prospective study. The patients with clinical or laboratory findings of elevated D-dimer level or elevated lactate dehydrogenase (LDH) level were suspected of embolism and underwent tomography.

RESULTS

PTE was detected in 26 patients (42%). A significant difference was not detected between tomography finding positive and negative embolisms in the patient group in terms of age or gender distribution (P=0.221 and P=0.416, respectively). No significant difference was detected between tomography finding positive and negative embolisms in the patient group in terms of elevated LDH or/and D-dimer levels (P=0.263 and P=1.000, respectively). The distribution of low-risk-factor patients in the non-embolism group, and the distribution of high-risk-factor patients in the embolism-positive group was statistically significantly high (P<0.001). There was no statistically significant difference between the groups (P=0.053). Correlation test showed no correlation between LDH and D-dimer levels. (r=0.214, P=0.180).

CONCLUSIONS

In conclusion, when a patient presents with chest pain, our carrying out LDH and D-Dimer tests will not exclude PTE without CTPA. However, we suggest that LDH isoenzymes should be studied in further research.

Effectiveness of d-dimer as a screening test for venous thromboembolism: an update

Venous thromboembolism (VTE) is the leading cause of morbidity and mortality among hospitalized patients. We searched the PubMed database and reviewed the articles published until June 2011. Articles related to the D-dimer and VTE were considered to write this paper. Many factors play a key role in changing the sensitivity and specificity of D-dimer testing, including the extent of thrombosis and fibrinolytic activity, duration of symptoms, anticoagulant therapy, comorbidity due to surgical or medical illnesses, inflammatory diseases, cancer, elderly age, pregnancy and the postpartum period, and previous VTE. Many previous studies have shown that the D-dimer test is highly sensitive (>95%) in acute deep venous thrombosis or pulmonary embolism, usually with a cut-off value of 500 μg FEU/l, which reasonably rules out acute VTE, particularly in patients with low clinical probability (LCP) or intermediate clinical probability. Patients with high D-dimer levels upon presentation may prompt a more intense diagnostic approach, irrespective of pretest probability. Studies performed after a negative D-dimer for 3 months proved the high negative predictive value (NPV) of D-dimer testing together with LCP in patients with suspected VTE. Among oncology patients, D-dimer testing has the highest sensitivity and NPV in excluding VTE. The new cutoff values of D-dimer testing were analyzed in a recent prospective study of pregnant women; they are 286 ng DDU/ml, 457 ng DDU/ml, and 644 ng DDU/ml for the first, second, and third trimesters, respectively.

Heightened clinical suspicion of pulmonary embolism and disregard of the D-dimer assay: a contemporary trend in an era of increased access to computed tomography pulmonary angiogram?

BACKGROUND

Prospective studies have shown that utilising qualitative D-dimers in those with a low Wells pre-test probability (PTP) of pulmonary embolism (PE) have significantly reduced the number of computed tomography pulmonary angiograms (CTPA) being performed. These studies have been based on a PE prevalence of approximately 6% in the low PTP group.

AIM

This study compares the diagnostic approach to PE in the study institution to well-established guidelines. The study also re-examines the cost-benefit analyses of qualitative d-dimers and CTPA in the low PTP group.

METHODS

A retrospective study of 169 consecutive CTPA requested in the emergency department of a major teaching hospital during a 12-month period.

RESULTS

The prevalence of PE was 0% (0/65), 11.7% (9/77) and 0% (0/2) in the low, moderate and high Wells PTP groups respectively, and 6.3% (9/144) overall. PTP was documented in 10 (6.9%) cases, and the qualitative Clearview Simplify D-dimer was only ordered in 33.8% (22/65) of low PTP subjects. The false positive D-dimer rate was 90.2% (37/41). Cost-benefit analysis and assay performance defines a narrow range of low PTP PE prevalence between 1% and 5% for the utilisation of the qualitative D-dimer assay.

CONCLUSIONS

The overall prevalence of PE in subjects undergoing CTPA was significantly lower compared with data in the literature. The authors recommend warranted clinical suspicion of PE should be confirmed by a senior physician prior to placing a patient in the PE work-up pathway. In such patients, the qualitative D-dimer assay should be utilised if PTP is low, and the exclusionary efficiency of the D-dimer will be improved in the setting of higher PE prevalence in this subgroup. Hospitals should audit local PE prevalence, as cost-benefit analyses raises questions about the effectiveness of D-dimers when PE prevalence is very low in the low PTP subgroup.

Pulmonary embolism in Bradford, UK: role of end-tidal CO2 as a screening tool

End-tidal CO2 (ETCO2) can represent dead space ventilation. The authors aimed to define the optimum ETCO2 to conclusively exclude a pulmonary embolic event. One hundred consecutive patients with suspected pulmonary embolisms (PEs) were enrolled over 6 months in 2012. Symptoms, demographic date, Wells' score, D-dimer levels and the gold standard computed tomography pulmonary angiogram (CTPA) results were collated for analysis. ETCO2 was measured within 24 hours of presentation in all 100 patients. Patient ages ranged from 18 years to 93 years. PE was diagnosed in 38% of cases. The average ETCO2 in patients with a positive CTPA was 3.35 kPa (range 2.4-4.2 kPa, SD 0.50). The average ETCO2 in patients without a PE was 4.41 kPa (range 1.3-6.6 kPa, SD 1.10). All patients positive for a PE obtained an ETCO2 <4.3 kPa (32.3 mmHg). This point (4.3 kPa) had a sensitivity and specificity (100% and 68% respectively), with a negative predictive value of 100% and positive predictive value of 66%. ETCO2 may reliably be used to screen and exclude patients with suspected PEs. If used in combination with D-dimer with clinical probability as a screening tool, CTPA will be required in only a minority of patients.

Doppler ultrasonography versus venography in the detection of deep vein thrombosis in patients with pulmonary embolism

In patients with acute pulmonary embolism (PE) the frequency of deep vein thrombosis (DVT) varies between 13-93%. The aim of this study was to compare Doppler ultrasonography (DUSG) and venography in the detection of DVT in patients with PE. Fifty-one patients who were clinically diagnosed as having PE from January 1st 2001 to January 31st 2005 were entered into the study and comorbid conditions and risk factors were noted. The diagnosis of PE was confirmed by ventilation-perfusion (V/Q) scintigraphy, spiral tomography and angiotomography while the diagnosis of DVT was made by DUSG and venography. DVT was confirmed by both DUSG and venography in 19 (37,3%) patients. In the remaining 32 patients DUSG was negative. Venography confirmed DVT in 6 of these patients while in 26 no DVT was found. The sensitivity and specifity of DUSG in the diagnosis of DVT were 76% and 100% respectively and the negative and positive predictive values were 81% and 100% respectively. The mean d-dimer concentration was 1,187 in patients with DVT and 641 in patients without DVT (p > 0.05). Aquired risk factors were found in 4 of 6 patients with DVT, CRP was elevated in 5 (83%) and ALT-AST were elevated in 2 (33%). Although DUSG alone is considered sufficient for the diagnosis of DVT, venography still remains the gold standard in the diagnosis of DVT. Especially in patients with PE, where the diagnosis of DVT may increase the success of treatment, venography or other diagnostic tools may be used instead of a second DUSG if the first DUSG is negative.

Association between plasma levels of D-dimer and fibrinogen/fibrin degradation products (FDP) for exclusion of thromboembolic disorders

BACKGROUND

D-dimer and fibrinogen/fibrin degradation products (FDP) levels are elevated in subjects with thromboembolic disorders, and the assays for detection of D-dimer and FDP are used in many laboratories for the investigation of these disorders. The aim of this study was to evaluate the association between the plasma levels of D-dimer and FDP in the investigation of thromboembolic disorders.

METHODS

D-dimer and FDP immunoassays were performed in 217 consecutive blood samples from subjects with suspected of thromboembolic disorders by use of Liatest D-dimer and Plasma FDP.

RESULTS

FDP results were classified in: <5, 5-20, >20 microg/mL, and D-dimer levels obtained in these groups ranged to 350-1,210 ng/mL, 420-1,960 ng/mL, and 1,190-51,170 ng/mL, respectively. A significant association between D-dimer levels and the reaction times necessary to occur agglutination in latex agglutination test for FDP was observed.

CONCLUSIONS

There was an association between plasma levels of D-dimer and FDP. The preliminary determination of FDP levels could be useful because it allows estimating the D-dimer levels before of the automated systems analysis, reducing costs associated to dilutions of plasma samples.

Magnitude of D-dimer matters for diagnosing pulmonary embolus

OBJECTIVE

The objective of this study is to determine whether the magnitude of the D-dimer correlates with a higher likelihood of pulmonary embolus (PE).

METHODS

We performed an electronic chart review at our academic, tertiary care center, annual emergency department (ED) census greater than 100000. All patients with a chest computed tomographic (CT) scan with intravenous contrast and an elevated D-dimer level obtained in the ED between January 2001 and July 2008 were identified. Specific, predetermined, predefined data elements including sex, age, D-dimer level, and final ED diagnosis were recorded by a hypothesis-blinded extractor using a preformatted data form. D-dimer level less than 0.58 μg/mL constitutes the normal laboratory reference range for our turbidometric D-dimer assay. Data were analyzed using standard statistical methods, and a linear regression analysis was performed for correlation analysis of D-dimer and diagnosis of PE.

RESULTS

We identified 544 subjects who had both a chest CT scan performed and an elevated D-dimer level obtained in the ED. Fifty-eight subjects (10.7%; mean D-dimer, 4.9 μg/mL) were diagnosed with PE, and 486 (89.3%; mean D-dimer, 2.0) did not have a PE. The percentages of PE diagnoses for D-dimers in the ranges 0.58 to 1.0, 1.0 to 2.0, 2.0 to 5.0, 5.0 to 20.0, and greater than 20.0 (n = 11) were 3.6%, 8.0%, 16.2%, 35.3%, and 45.5%, respectively. The positive predictive value of PE for D-dimer level cutoffs of greater than 0.58, greater than 1.0, greater than 2.0, greater than 5.0, and greater than 20.0 was 10.7%, 14.6%, 22.2%, 37.8%, and 45.5%, respectively. Increasing D-dimer values were strongly correlated with the presence of PE (odds ratio, 1.1685 per stratum; P < .001).

CONCLUSION

Increasing magnitude of D-dimer correlates with increasing likelihood of PE diagnosed by CT angiography.

Unusual presentation of spontaneous splenic haematoma due to severe pancreatitis: a cautionary tale

We report the case of a patient with multiple splenic complications from chronic pancreatitis with pseudocyst formation, including splenic vein thrombosis, subcapsular splenic haematoma and splenic artery pseudoaneurysm. The initial presentation was associated with pleuritic chest pain, clinically resembling symptoms of pulmonary embolism. The patient was treated with therapeutic low-molecular-weight heparin, without confirmatory imaging. However, the latter arranged computed tomographic pulmonary angiogram was negative, while the abdominal sequences of the CT revealed the splenic haematoma as causative pathology. The patient was initially treated conservatively, and discharged from inpatient care. On a subsequent CT, a pseudoaneurysm of the splenic artery was found and treated with coil embolisation. The patient is currently awaiting definitive management of the pancreatic pseudocyst.

A model for calculating the within-subject biological variation and likelihood ratios for analytes with a time-dependent change in concentrations; exemplified with the use of D-dimer in suspected venous thromboembolism in healthy pregnant women

BACKGROUND

Within-subject biological variation and reference change value (RCV) are difficult to calculate for an analyte with a changing concentration. The aim of this study was to develop a model to examine if it was possible to transform an analyte with a time-dependent change in concentration into a 'steady-state' situation by the use of 'multiples of the median' (MoM) and its natural logarithm (lnMoM). In addition, we wanted to extend the RCV concept, using likelihood and odds ratios, to calculate the post-test probabilities for disease. D-dimer in pregnancy is used as an example.

METHODS

Blood samples from 18 healthy pregnant and 18 healthy non-pregnant women were collected every fourth week. MoM of the D-dimer concentrations was calculated for each four-week interval to obtain a 'steady-state' situation for the D-dimer concentrations. The 'normalized' values were then transformed to the lnMoM to obtain a Gaussian distribution, used for the estimation of biological variation.

RESULTS

Median D-dimer concentrations increased six-fold during pregnancy. Within-subject variation (SD) of lnMoM D-dimer was 0.27 during pregnancy and 0.23 in non-pregnant women, with RCVs of 0.72 and 0.90, respectively.

CONCLUSIONS

By using the lnMoM model, an increasing concentration of an analyte can be transformed to a steady-state situation and the within-subject biological variation and its derived parameters can be calculated.

Diagnosis of pulmonary embolism: Advances and pitfalls

The signs and symptoms of patients with pulmonary embolism (PE) form a wide spectrum and considerably overlap with other cardiopulmonary diseases. Timely recognizing of this disease therefore remains challenging, but is of vital importance to avoid PE-related morbidity and mortality. To aid and standardize the initial diagnostic approach of patients with suspected PE, clinical probability rules have been developed and simplified for use in clinical practice. It has been demonstrated by clinical outcome studies that it is safe and of high clinical utility to exclude PE on the basis of an unlikely clinical probability and a normal D-dimer test result. For the remaining patients with suspected PE, imaging tests are required. The introduction of multi-detector computed tomographic pulmonary angiography (MD-CTA) has significantly improved the detection of PE, and this test is now regarded as the imaging test of first choice. This review will focus on recent advances and pitfalls that remain in the diagnostic work-up of patients with suspected acute PE.

[Interest of echocardiography in the diagnosis and monitoring of a pulmonary embolism complicating a free-floating thrombus in right heart cavities]

We report the case of a 50-year-old patient admitted in ICU for a pulmonary embolism associated with a large thrombus in right heart cavities discovered during an assessment of faintness. Despite an excellent haemodynamic tolerance, there was a systolic and diastolic right ventricular failure and immediate threat to life. The treatment mainly relies on intravenous thrombolysis with excellent results both on thrombus lysis and on the right heart performance. Echocardiography proved to be an essential tool during the management of this patient to ensure the effectiveness and to monitor the whole procedure of thrombolysis.

The combination of four different clinical decision rules and an age-adjusted D-dimer cut-off increases the number of patients in whom acute pulmonary embolism can safely be excluded

Four clinical decision rules (CDRs) (Wells score, Revised Geneva Score (RGS), simplified Wells score and simplified RGS) safely exclude pulmonary embolism (PE), when combined with a normal D-dimer test. Recently, an age-adjusted cut-off of the D-dimer (patient's age x 10 μg/l) safely increased the number of patients above 50 years in whom PE could safely be excluded. We validated the age-adjusted D-dimer test and assessed its performance in combination with the four CDRs in patients with suspected PE. A total of 414 consecutive patients with suspected PE who were older than 50 years were included. The proportion of patients in whom PE could be excluded with an 'unlikely' clinical probability combined with a normal age-adjusted D-dimer test was calculated and compared with the proportion using the conventional D-dimer cut-off. We assessed venous thromboembolism (VTE) failure rates during three months follow-up. In patients above 50 years, a normal age-adjusted D-dimer level in combination with an 'unlikely' CDR substantially increased the number of patients in whom PE could be safely excluded: from 13-14% to 19-22% in all CDRs similarly. In patients over 70 years, the number of exclusions was nearly four-fold higher, and the original Wells score excluded most patients, with an increase from 6% to 21% combined with the conventional and age-adjusted D-dimer cut-off, respectively. The number of VTE failures was also comparable in all CDRs. In conclusion, irrespective of which CDR is used, the age-adjusted D-dimer substantially increases the number of patients above 50 years in whom PE can be safely excluded.

Pneumothorax complicating pulmonary embolism after combined spinal epidural anesthesia in a chronic smoker with open femur fracture

Pulmonary embolism during or after regional anaesthesia is although very rare, it has been reported in cases undergoing lower limb orthopedic procedures. We presenting a 48 years old male, a known smoker since 25 years, with history of road traffic accident and open fracture right femur for external fixation. Combined spinal epidural anaesthesia was given. After 35 minutes patient complained dyspnea and chest pain. SpO2 decreased to 82% from 100%. Continuous positive airway pressure with 100% oxygen was given. SpO2 increased from 82% to 96%. Suddenly he had bouts of cough and SpO2 became 79-80% with unstable haemodynamics. On chest auscultation there was decreased breath sounds on right side with limited expansion. Trachea was intubated after inducing anaesthesia with fentanyl 70 μg and thiopental 300 mg. Chest radiograph showed right sided pneumothorax. Intercostal drain with a water seal was put. After 5 minutes HR was 80/min, BP was 110/69 mmHg and SpO2 was 97%. Pulmonary thromboembolism secondary to deep vein thrombosis was suspected and was confirmed by D-dimer Elisa and color Doppler of lower limbs. Patient was shifted to intensive care unit after completion of surgery. Anticoagulant therapy was started. He was weaned from the ventilator on 3rd day and trachea was extubated. Chest drain was removed after 9 days and he was discharged from hospital on 15th post operative day.