Diagnosis of pulmonary embolism

Utilization of a Guideline-recommended Imaging Paradigm for Pregnant Patients With Suspicion of Pulmonary Embolism

PURPOSE

A dose reduction imaging paradigm utilizing chest x-ray (CXR) to triage between computed tomography pulmonary angiography (CTPA) and lung scintigraphy (LS) was introduced in 2001 and adopted in 2012 by the American Thoracic Society/Society of Thoracic Radiology (ATS) guideline for the evaluation of pulmonary embolism in pregnancy. We aimed to assess the utilization of this imaging paradigm preadoption and postadoption by the ATS guideline, and identify factors associated with its utilization.

MATERIALS AND METHODS

This retrospective cohort study evaluated consecutive pregnant patients who received CTPA or LS for the evaluation of pulmonary embolism in pregnancy at 2 tertiary hospitals between September 2008 and March 2017, excluding 2012 for guideline release washout. Utilization of the imaging paradigm was defined per patient by the use of CXR before advanced imaging, with CTPA performed following positive CXR and LS performed following negative CXR. Multivariate analyses were performed to assess factors associated with utilization of the imaging paradigm. P <0.05 is considered significant.

RESULTS

Overall, 9.8% (63/643) of studies utilized the dose reduction imaging paradigm, 13.3% (34/256) before the guidelines, and 7.5% (29/387) after. Multivariable analysis showed that the dose reduction imaging paradigm utilization was higher for inpatients (odds ratio [OR]: 4.5) and outpatients (OR: 3.1) relative to the emergency department patients, and lower for second (OR: 0.3) and third (OR: 0.2) trimester patients, without significant differences by study priority, patient age, or patient race.

CONCLUSIONS

Guideline-recommended dose reduction imaging paradigm utilization was low, and decreased after guideline publication. Utilization varied by patient setting and trimester, which are potential targets for interventions to improve guideline compliance.

Rate of Nondiagnostic Computerized Tomography Pulmonary Angiograms (CTPAs) Performed for the Diagnosis of Pulmonary Embolism in Pregnant and Immediately Postpartum Patients

Objective

To evaluate the nondiagnostic rate of computed tomography pulmonary angiography (CTPA) in pregnant and postpartum patients with suspected pulmonary embolism (PE) to determine whether CTPA or ventilation-perfusion (VQ) scan should be considered first line imaging in this patient population considering their equivalent accuracy and the greater radiation exposure to proliferating breast tissue of CTPA.

Methods

All pregnant/postpartum female patients between 18 and 50 years of age who had CTPA within the Eastern Health Authority between November 2012 and November 2016 were included. Each scan was evaluated for nondiagnosis based on two criteria: contrast density in the main pulmonary artery, and respiratory motion artefact. If either of these criteria were not met, the scan was labelled as nondiagnostic.

Results

The nondiagnostic rate overall was 43% (n=83). This is similar to current literature values for rates of CTPA nondiagnosis, and comparable to the reported diagnostic quality of the reporting radiologist. This is much greater compared to rates of ventilation/perfusion nondiagnosis in comparable populations. Even in patients with normal chest radiographs, which represents the main patient group where VQ may be considered as an alternative, the nondiagnostic rate of CT is much higher.

Conclusion

This is the first study to attempt to identify an objective method of determining nondiagnosis in pregnant and postpartum patients undergoing a CTPA. Our results strengthen the argument that alternative imaging should be considered when investigating for PE in this population in order to protect the proliferating breast tissue, and VQ scan should be considered especially in patients with normal chest X-rays.

First in vivo magnetic particle imaging of lung perfusion in rats

Pulmonary embolism (PE), along with the closely related condition of deep vein thrombosis, affect an estimated 600 000 patients in the US per year. Untreated, PE carries a mortality rate of 30%. Because many patients experience mild or non-specific symptoms, imaging studies are necessary for definitive diagnosis of PE. Iodinated CT pulmonary angiography is recommended for most patients, while nuclear medicine-based ventilation/perfusion (V/Q) scans are reserved for patients in whom the use of iodine is contraindicated. Magnetic particle imaging (MPI) is an emerging tracer imaging modality with high image contrast (no tissue background signal) and sensitivity to superparamagnetic iron oxide (SPIO) tracer. Importantly, unlike CT or nuclear medicine, MPI uses no ionizing radiation. Further, MPI is not derived from magnetic resonance imaging (MRI); MPI directly images SPIO tracers via their strong electronic magnetization, enabling deep imaging of anatomy including within the lungs, which is very challenging with MRI. Here, the first high-contrast in vivo MPI lung perfusion images of rats are shown using a novel lung perfusion agent, MAA-SPIOs.

Imaging techniques used in the diagnostic workup of acute venous thromboembolic disease

Early diagnosis is one of the most important factors affecting the prognosis of pulmonary embolism (PE); however, the clinical presentation of PE is often very unspecific and it can simulate other diseases. For these reasons, imaging tests, especially computed tomography angiography (CTA) of the pulmonary arteries, have become the keystone in the diagnostic workup of PE. The wide availability and high diagnostic performance of pulmonary CTA has led to an increase in the number of examinations done and a consequent increase in the population's exposure to radiation and iodinated contrast material. Thus, other techniques such as scintigraphy and venous ultrasonography of the lower limbs, although less accurate, continue to be used in certain circumstances, and optimized protocols have been developed for CTA to reduce the dose of radiation (by decreasing the kilovoltage) and the dose of contrast agents. We describe the technical characteristics and interpretation of the findings for each imaging technique used to diagnose PE and discuss their advantages and limitations; this knowledge will help the best technique to be chosen for each case. Finally, we comment on some data about the increased use of CTA, its clinical repercussions, its "overuse", and doubts about its cost-effectiveness.

Right bundle branch block and SIQIII-type patterns for risk stratification in acute pulmonary embolism

INTRODUCTION

Risk stratification in acute pulmonary embolism (PE) is crucial for identification of patients with poor prognosis. We aimed to investigate the ECG alterations of right bundle branch block (RBBB) and SIQIII-type patterns for risk stratification in acute PE.

MATERIALS AND METHODS

Retrospective analysis of PE patients, treated in the Internal Medicine Department, was performed. Patients with RBBB and/or SIQIII-type were compared with those without both patterns. Logistic regression models for association between these ECG alterations and respectively right ventricular dysfunction (RVD), high-risk PE status and myocardial injury were computed.

RESULTS

175 patients were included for this retrospective analysis. Total study sample comprised 37 PE patients (21.1%) with RBBB and/or SIQIII-type patterns and 138 PE patients (78.9%) without both signs. Heart rate (97.4±17.2 vs. 93.2±26.8/min, P=0.021), cardiac troponin I values (0.19±0.38 vs. 0.11±0.24, P=0.003) and percentage of patients with RVD (83.9% vs. 52.7%, P=0.005) were significantly higher in PE patients with RBBB and/or SIQIII-type patterns compared to PE patients without both ECG alterations. Multi-variate logistic regression models adjusted for age and gender revealed significant associations between RBBB and RVD (OR3.942, 95% CI1.054-14.747, P=0.042) and between SIQIII-type patterns and RVD (OR5.667, 95% CI1.144-28.071, P=0.034). The association between RBBB and cardiac injury (cTnI>0.4ng/ml) (OR2.531, 95% CI 0.973-6.583, P=0.06) showed a borderline significance, while the association between SIQIII-type patterns and cardiac injury was significant (OR3.956, 95% CI1.309-11.947, P=0.015).

CONCLUSIONS

RBBB and SIQIII-type patterns were both associated with RV overload and cardiac injury. RBBB and SIQIII-type patterns were connected with 3.9-fold and 5.7-fold elevated risk of RVD, respectively.

Thrombocytosis is Predictive of Postoperative Pulmonary Embolism in Patients With Gynecologic Cancer

Objectives

The prompt diagnosis of postoperative pulmonary embolism (PE) in gynecologic oncology patients is imperative, but the clinical presentation is nonspecific in this high-risk group. We sought to determine risk factors and clinical findings that may assist clinicians in diagnosing PE in the inpatient setting.

Methods

Radiology data were queried to identify patients with gynecologic cancer who had a postoperative PE evaluation with computed tomography pulmonary angiography (CT-PA). Patient clinical findings at the time of the PE evaluation were abstracted, and univariate and multivariate regression analyses were performed to identify predictors of PE.

Results

For 6 years, there were 2498 major gynecologic oncology surgical procedures performed at our institution. Within 14 days of surgery, 107 CT-PA studies were obtained with a positive study rate of 24.3%. In patients with and without PE, there was no significant difference noted for age, oxygen saturations, body mass index and heart rate. After controlling for stage, history of venous thromboembolism (VTE), heart rate, and oxygen saturation, platelet count (odds ratio, 1.26 per 50 counts increase; 95% confidence interval, 1.07–1.48; P = 0.006) and history of VTE (odds ratio, 17.1; 95% confidence interval, 1.77–Inf, P = 0.014) were identified as independent predictors of PE in the multivariate model.

Conclusions

Although clinicians often use tachycardia and low oxygen saturation as triggers to order PE imaging studies, these signs have a very low specificity. Given the findings of our study, accounting for high platelet count and history of VTE increases the pretest probability of CT-PA study.

Automated iterative neutrosophic lung segmentation for image analysis in thoracic computed tomography

PURPOSE

Lung segmentation is a fundamental step in many image analysis applications for lung diseases and abnormalities in thoracic computed tomography (CT). The authors have previously developed a lung segmentation method based on expectation-maximization (EM) analysis and morphological operations (EMM) for our computer-aided detection (CAD) system for pulmonary embolism (PE) in CT pulmonary angiography (CTPA). However, due to the large variations in pathology that may be present in thoracic CT images, it is difficult to extract the lung regions accurately, especially when the lung parenchyma contains extensive lung diseases. The purpose of this study is to develop a new method that can provide accurate lung segmentation, including those affected by lung diseases.

METHODS

An iterative neutrosophic lung segmentation (INLS) method was developed to improve the EMM segmentation utilizing the anatomic features of the ribs and lungs. The initial lung regions (ILRs) were extracted using our previously developed EMM method, in which the ribs were extracted using 3D hierarchical EM segmentation and the ribcage was constructed using morphological operations. Based on the anatomic features of ribs and lungs, the initial EMM segmentation was refined using INLS to obtain the final lung regions. In the INLS method, the anatomic features were mapped into a neutrosophic domain, and the neutrosophic operation was performed iteratively to refine the ILRs. With IRB approval, 5 and 58 CTPA scans were collected retrospectively and used as training and test sets, of which 2 and 34 cases had lung diseases, respectively. The lung regions manually outlined by an experienced thoracic radiologist were used as reference standard for performance evaluation of the automated lung segmentation. The percentage overlap area (POA), the Hausdorff distance (Hdist), and the average distance (AvgDist) of the lung boundaries relative to the reference standard were used as performance metrics.

RESULTS

The proposed method achieved larger POAs and smaller distance errors than the EMM method. For the 58 test cases, the average POA, Hdist, and AvgDist were improved from 85.4±18.4%, 22.6±29.4 mm, and 3.5±5.4 mm using EMM to 91.2±6.7%, 16.0±11.3 mm, and 2.5±1.0 mm using INLS, respectively. The improvements were statistically significant (p<0.05). To evaluate the accuracy of the INLS method in the identification of the lung boundaries affected by lung diseases, the authors separately analyzed the performance of the proposed method on the cases with versus without the lung diseases. The results showed that the cases without lung diseases were segmented more accurately than the cases with lung diseases by both the EMM and the INLS methods, but the INLS method achieved better performance than the EMM method in both cases.

CONCLUSIONS

The new INLS method utilizing the anatomic features of the rib and lung significantly improved the accuracy of lung segmentation, especially for the cases affected by lung diseases. Improvement in lung segmentation will facilitate many image analysis tasks and CAD applications for lung diseases and abnormalities in thoracic CT, including automated PE detection.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Clinical, historical and diagnostic findings associated with right ventricular dysfunction in patients with central and non-massive pulmonary embolism

Right ventricular dysfunction during acute pulmonary embolism (PE) predisposes to hemodynamic instability and cardiogenic shock. Aim of this case-control study was to determine the clinical, historical and diagnostic findings associated with right ventricular dysfunction in patients with acute PE involving the main or segmental pulmonary arteries (central PE) and without hemodynamic instability on admission to the Emergency Department (ED) (non-massive PE). From January 1, 2002 to December 31, 2005, 211 patients with central PE were admitted to the Department of Emergency Medicine of the "Antonio Cardarelli" Hospital (Naples, Italy). One hundred eighteen of them had echocardiographic evidence of right ventricular dysfunction on admission to the ED. A history of type 2 diabetes mellitus and chronic obstructive pulmonary disease were significantly associated with an increased risk of this PE-related complication. Compared to patients without right ventricular dysfunction, those with right ventricular dysfunction showed higher levels of markers of cardiac damage, and a significant impairment of respiratory function. Echocardiographic evidence of right ventricular dysfunction on admission to the ED was significantly associated with the occurrence of hemodynamic instability and cardiogenic shock during the PE clinical course. The study results indicate that a history of type 2 diabetes mellitus and chronic obstructive pulmonary disease are significantly associated with the occurrence of right ventricular dysfunction in patients with non-massive and central PE independent of age, gender and other historical and clinical variables detectable on admission to the ED.

The prevalence of symptomatic and coincidental pulmonary embolism on computed tomography

PURPOSE

To investigate the proportion of pulmonary embolism (PE) on computed tomographic pulmonary angiography (CTPA) and the proportion of coincidental PE on regular contrast-enhanced CT in oncological and nononcological patients.

METHODS

This study received internal review board approval and was Health Insurance Portability and Accountability Act compliant. All consecutive adult patients who had contrast-enhanced chest CT or dedicated CTPA during January 2005 were studied. Procedural codes were used to identify cases, and all CT images were reviewed. Clinical data collected included oncology status, chemotherapy regimen, site of tumor, and location of PE. chi2 Tests were used for statistical analysis.

RESULTS

Two hundred twenty-nine patients had CTPA, and 27 (11.8%) of them were positive for PE. Of 1168 patients who had contrast-enhanced CT for other indications, coincidental PE was found in 21 patients (1.8%). The proportions of coincidental PE were 3.3% of patients with progressive cancer, 2.5% of patients with stable cancer, 0.7% of patients with no evidence of cancer posttreatment, and 1.0% of nononcological patients. Coincidental PE was found more frequently in patients with progressive cancer compared with nononcological patients (P = 0.035). Patients who were on chemotherapy also had a higher risk of coincidental PE (P=0.019).

CONCLUSIONS

The prevalence of symptomatic PE on dedicated CTPA was 11.8%, and the rate of coincidental PE on contrast-enhanced CT was 1.8%. Coincidental PE was significantly higher inpatients with progressive cancer or those receiving chemotherapy.

Troponin I and right ventricular dysfunction for risk assessment in patients with nonmassive pulmonary embolism in the Emergency Department in combination with clinically based risk score

To determine whether troponin I (cTnI) and right ventricular (RV) dysfunction predict adverse in-hospital outcomes in patients admitted to the Emergency Department (ED) with definite nonmassive pulmonary embolism (PE) independent of and in addition to a recently validated clinical prognostic risk score. From a pool of 168 patients with suspected PE, 89 had nonmassive PE confirmed by spiral lung angio-computed tomography. By the clinical prognostic score, in our study sample, 14% had very low risk; 17% had low risk, 20% had intermediate risk, whereas high risk and very high risk were identified in 29 and 20%, respectively. Prevalence of elevated cTnI (>0.1 microg/L, 57%) at admission was comparable among patients grouped by clinical prognostic score (P = NS); echocardiographic RV dysfunction (54%) was more prevalent with intermediate or high clinical risk score (P < 0.02). Increased cTnI predicted primary end-point (development of hemodynamic instability, overall 33 cases, 37%) independent of and in addition to the clinical risk class and RV dysfunction (P < 0.01 for interaction). Fatal events (12 cases, 14%, 5 definite, 7 possible PE-related) were predicted by higher clinical risk score (P < 0.05). In patients with nonmassive central PE admitted to the ED, increased cTnI contributed to identifying those with increased risk of development of hemodynamic instability independent of and in addition to a validated clinically based risk score.

Forensic Lung Pathology

Sudden and unexpected natural deaths and nonnatural deaths may result from various pulmonary conditions. Additionally, several nonpulmonary conditions of forensic significance may be complicated by the development of respiratory lesions. Certain situations with pulmonary pathology are particularly likely to be critically scrutinized and may form the basis of allegations of medical negligence, other personal injury liability, or wrongful death.1

Increased troponin I predicts in-hospital occurrence of hemodynamic instability in patients with sub-massive or non-massive pulmonary embolism independent to clinical, echocardiographic and laboratory information

INTRODUCTION

Whether in patients with acute central sub-massive or non-massive pulmonary embolism, mild troponin I increase (>0.03 mug/L) predicts in-hospital occurrence of hemodynamic instability and death independent to prognostically relevant clinical, laboratory and echocardiographic information is not fully established.

METHODS AND RESULTS

We evaluated consecutively patients admitted to the Emergency Room for pulmonary embolism; those in stable hemodynamics in whom central pulmonary embolism was confirmed by spiral-computed tomography were recruited. All participants underwent standardized study protocol, including clinical and diagnostic evaluation for assessment of severity of pulmonary embolism; therapy was established accordingly; troponin I was measured, but treatment protocol was not affected by knowledge of troponin I levels. Of 90 patients enrolled in the study, 33 (37%) developed hemodynamic instability during hospitalization (on average, 90 h +/-20 from admission). Troponin I was >0.03 microg/L in 56% of the study population at admission, and predicted occurrence of hemodynamic instability during hospitalization (adjusted hazard ratio 9.8, 95% confidence interval 1.2-79.2), independent to age, gender, co-morbidity, systolic blood pressure, CK-MB, echocardiographic right ventricular dysfunction and other covariates. Twelve patients died during hospitalization (mean time to event 107 h +/-24 from admission); troponin I >0.03 microg/L predicted mortality in univariate analysis, but not after accounting for age, sex and clinical variables. Nevertheless, higher troponin as continuous variable correlated with higher likelihood of in-hospital death (adjusted likelihood ratio 2.2/microg/L, 95% confidence interval 1.1-4.3) in multivariate analysis. In a further multivariate model, CK-MB predicted mortality independent of covariates and troponin I.

CONCLUSIONS

In patients with acute central sub-massive or non-massive pulmonary embolism, even mild increase in troponin I >0.03 microg/L may provide relevant short-term prognostic information independent to clinical, laboratory and echocardiographic data.

Investigating suspected pulmonary embolism during pregnancy

Pulmonary embolism (PE) is the commonest cause of maternal death in UK. It is a frequently occurring diagnostic challenge. The false negative and false positive rates for the diagnosis of PE are spectacularly high. Undiagnosed PE has a mortality rate as high as 30%, which falls to 2-8% if the condition is diagnosed and treated appropriately. [Rodger M, Wells PS. Diagnosis of pulmonary embolism. Thromb Res 2001;103:v225-38; Guidelines on Diagnosis and Management of Acute Pulmonary Embolism. Task Force on Pulmonary Embolism, European Society of Cardiology. Eur Heart J 2000;21(16):1301-36]. Physiologic changes of pregnancy further complicate the diagnosis of PE. Although the danger of maternal and foetal death secondary to maternal PE and unnecessary anticoagulation far outweighs the risk of radiation involved in scanning, doctors still hesitate to request appropriate investigation because of concern regarding radiation exposure to the foetus and the absence of any clear, updated guideline. Worried parents need to be counselled appropriately before tests to alleviate anxiety and misunderstanding.

Chest Pain: A Clinical Assessment

Chest pain is one of the most common presentations in emergency medicine. The initial evaluation should always consider life-threatening causes such as aortic dissection, pulmonary embolism, pneumothorax, pneumomediastinum, pericarditis, and esophageal perforation. Radiographic imaging is performed in tandem with the initial clinical assessment and stabilization of the patient. Radiologic findings are key to diagnosis and management of this entity.

Pulmonary embolism: an unsuspected killer

The presentation of PE is often subtle and may mimic other diseases. Many pulmonary emboli invariably preclude diagnosis by their occult nature or by leading to rapid death from cardiopulmonary arrest. In patients who do manifest symptoms from PE, accurate diagnosis is essential. Often it is difficult to distinguish the vague symptoms of PE from other diagnoses, such as acute coronary syndrome, pneumonia, COPD, CHF,aortic dissection, myocarditis or pericarditis, pneumothorax, and musculo-skeletal or gastrointestinal causes. Regardless of the presentation, the most fundamental step in making the diagnosis of PE is first to consider it. Historical clues and risk factors should raise the clinician's suspicion.PE is an unsuspected killer with a nebulous presentation and high mortality. In all likelihood, PE will remain an elusive diagnosis despite advances in technology and a wealth of research. A high index of suspicion is required, but no amount of suspicion would eliminate all missed cases. Patients with significant underlying cardiopulmonary disease seem to be the most challenging. Patients with significant comorbidity have poor reserve and are likely to have poor outcomes, especially if the diagnosis is not made and anticoagulation is not initiated early. Controversy exists over the best diagnostic approach to PE. A battery of diagnostic studies is available, with few providing definitive answers. Studies such as CT may be helpful at some institutions but offer poor predictive value at others. Other diagnostic tests are not universally available. It is hoped that further research and improvements in current diagnostic modalities will clear some of the current confusion and controversy of this ubiquitous and deadly disease.

Diagnosis of pulmonary embolism: a cost-effectiveness analysis

OBJECTIVE

Pulmonary embolism is a major cause of maternal death. The work up for suspected pulmonary embolism is complex, with many potential diagnostic options. We performed a cost analysis to evaluate which of several diagnostic strategies was the most cost-effective with the least number of deaths from pulmonary embolism.

STUDY DESIGN

We created a decision tree to evaluate the following strategies: (1) Compression ultrasonography followed by anticoagulation (if there is a positive result) or secondary tests, ventilation perfusion scans or spiral computed tomography (if there is a negative result); high probability ventilation perfusion scans (a positive test result) resulted in anticoagulation; low probability ventilation perfusion scans (a negative test) resulted in no treatment; intermediate tests that resulted in a second test (computed tomography or pulmonary angiography). (2) Ventilation perfusion scans as a primary test followed by anticoagulation. (3) Computed tomography followed by anticoagulation (if there is a positive result). The following assumptions were made: The incidence of pulmonary embolism in pregnant women with suspected pulmonary embolism is 5%; 40% of documented pulmonary embolisms have a positive compression ultrasound result; 10% of ventilation perfusion scans for suspected pulmonary embolism are high probability, 60% are indeterminate, and 30% are low probability for pulmonary embolism; the sensitivity of computed tomography is 95%; the sensitivity of angiography is 98%. The assumed mortality rate of treated pulmonary embolism is 0.7% and of untreated pulmonary embolism in pregnancy is 15% (range, 10%-50%). The angiography-associated mortality rate is 0.5%, and the anticoagulation associated mortality rate is 0.2%. The following costs were used for the model: compression ultrasonography, 200.00 dollars; ventilation perfusion scans, 400.00 dollars; angiography, 1000.00 dollars; computed tomography, 500.00 dollars; and anticoagulation, 5982.00 dollars. With baseline assumptions, spiral computed tomography as the initial diagnostic regimen was found to be the most cost-effective at 17,208 dollars per life saved. Sensitivity analyses were performed over a wide range of assumptions that included alteration of the probability of pulmonary embolism, the sensitivity of computed tomography, ventilation perfusion scans, and compression ultrasonography, the cost of computed tomography, and the mortality rate of untreated pulmonary embolism. Our findings remained robust over a wide range of assumptions.

CONCLUSION

Suspected pulmonary embolism remains a diagnostic quandary. Our analysis indicated that spiral computed tomography offers the most cost-effective method for diagnosing this potentially fatal condition.

[Pulmonary embolism: analysis of cases without initial suspicion and sensitivity of three clinical models]

BACKGROUND AND OBJECTIVE

Pulmonary embolism (PE) is a frequent and severe condition. Although clinical models do exist, many patients are wrongly diagnosed. Our objective was to evaluate the clinical characteristics of patients with PE who are admitted at a hospital without initial clinical suspicion of it. We also evaluated the sensitivity of three clinical models in order to categorize the pre-test probability of PE.

PATIENTS AND METHOD

Retrospective review of clinical cases of PE diagnosed in a teaching hospital during one year. We compared the clinical features of patients whose PE was not initially suspected with those of patients in whom PE was a first diagnosis. The three clinical models were applied in all cases.

RESULTS

58 patients were identified. In 15 out of them (26%), PE was not an initial diagnosis. Patients without an initial PE suspicion were older, and previous surgery was less frequent among them. The clinical models exhibited sensitivities (60, 85, 89%) which were lower than those previously reported but higher than the doctor's initial clinical suspicion (74%). The models showed bad agreement between them (kappa = 0.06-0.1).

CONCLUSIONS

An initial misdiagnosis of PE is not justified by atypical clinical characteristics. The use of clinical models would improve the clinical suspicion.

Pulmonary embolism

PE is one of the great challenges in medicine. It is a disease that carries with it a high mortality rate, yet no historical piece of information, physical examination finding, or diagnostic modality is perfect at excluding its possibility. Emergency physicians must be vigilant about considering PE in the differential diagnosis of a variety of presenting complaints and must use a variety of diagnostic and therapeutic options as they manage patients with suspected or confirmed PE. The diagnostic options range from bedside diagnostic tests to highly specialized imaging available at only specialized institutions. Knowing the advantages and disadvantages of each of the diagnostic modalities assists the physician in employing the best test. Therapeutic options also vary widely and include anticoagulation, vena caval interruption, systemic thrombolysis, embolectomy, and other therapeutic adjuncts, such as ECMO and inhaled nitric oxide. Similarly, awareness of the indications and contraindications to the varied therapeutic agents ensures appropriate therapy when the diagnosis is made.