Diagnosing pulmonary embolism

Diagnosing pulmonary embolus (PE) remains one of the great challenges of emergency medicine. The diagnosis relies on a balance of probabilities rather than any definitive test. The probability is based on history, examination and investigations. The principal investigations are chest X-ray, arterial blood gas, electrocardiograph, ventilation perfusion scan, ultrasound and angiography where necessary. Newer techniques such as CT scan and magnetic resonance imaging will become more useful as the technology improves. Transoesophoegeal echocardiography is an important investigative tool for massive PE. Thrombolysis is increasingly being used in the management of PE and the higher risk of adverse outcome should be balanced against the probability of false positive results and the use of invasive angiography.     

Diagnosing pulmonary embolism: A question of too much choice?

The diagnosis of pulmonary embolism (PE) is difficult with many patients treated without the disease or left untreated without an adequate diagnostic work up. Recent advances in PE diagnosis are reviewed. The use of risk stratification in PE diagnosis is strongly recommended and evidence on how it can best be performed summarized. The Ginsberg/Wells stratification rule is recommended currently as the best validated rule. Computed tomographic pulmonary angiography (CTPA) was found to have quite poor sensitivity and to be poorly validated. It is recommended as adequate as a positive test in moderate/high risk groups and an exclusionary test in low risk groups or where an adequate alternative diagnosis is found. For D‐Dimer tests the only test with adequate sensitivity and validation in management studies is the VIDAS© D‐Dimer. This is in low/intermediate risk groups in the ED population. The Simpli‐Red© test is also reviewed but is too insensitive for most populations. Echocardiography: this is good in compromised patients as it is a bedside test which when negative virtually excludes PE. If positive in the right setting it has a high positive predictive value. A negative echocardiogram predicts a benign clinical course for PE. The rest of the paper details the authors approach to integrating these new techniques with established algorithms and where progress is likely to occur in the next few years. These include improvements in CTPA (plus the addition of CT venography), new point of care D‐Dimer tests, better risk stratification rules and integration of new strategies with artificial neural networks or computerized guidelines.     

A novel ECG parameter for diagnosis of acute pulmonary embolism: RS time: RS time in acute pulmonary embolism

ObjectivesPulmonary embolism (PE) is one of the leading causes of cardiovascular mortality worldwide. Electrocardiography (ECG) may provide useful information for patients with acute PE. In this study, we aimed to investigate the diagnostic value of the QRS duration and RS time in inferolateral leads in patients admitted to the emergency department, and pre-diagnosed with acute PE.MethodsWe retrospectively enrolled 136 consecutive patients, admitted to the emergency department, pre-diagnosed with the clinical suspicion of acute PE, and underwent computerized tomographic pulmonary angiography (CTPA) to confirm the PE diagnosis. The study subjects were divided into two groups according to the presence or absence of PE, and the independent predictors of PE were investigated.ResultsSixty-eight patients (50%) had PE. Patients with PE had a longer RS time. Among the ECG parameters, only RS time was an independent predictor of PE (OR: 1.397, 95% CI: 1.171–1.667; p < 0.001). The ROC curve analyses revealed that the cut-off value of RS time for predicting acute PE was 64.20 ms with a sensitivity of 85.3% and a specificity of 79.4% (AUC: 0.846, 95%CI: 0.749–0.944; p < 0.001). In the correlation analyses; the RS time was correlated with RV end-diastolic diameter (r = 0.422; p < 0.001), RV/left ventricle (LV) ratio (r = 0.622; p < 0.001), and systolic pulmonary artery pressure (SPAP) (r = 0.508; p < 0.001).ConclusionAs a novel ECG parameter, RS time could be measured for each patient. A longer RS time can be a very useful index for diagnosing acute PE as well as for estimating the RV end-diastolic diameter and SPAP.     

Diagnostic approach to pulmonary embolism: our strategy

The nonspecificity and variety of clinical features in acute pulmonary embolism account for a high suspicion rate, with a further exclusion of the diagnosis in up to 80% of cases. Arterial blood gas analysis and other laboratory tests are highly nonspecific, and suggestive signs on the electrocardiogram are uncommon. The plain chest X-ray often yields valuable information. Lung scan, when normal, has the great advantage of excluding pulmonary embolism. At present, no procedure has superseded pulmonary angiography to attest the presence of emboli. Angiography will probably gain widespread acceptance with the larger use of thrombolysis.     

Electrocardiographic manifestations: pulmonary embolism

The electrocardiographic findings associated with pulmonary embolism have been well described in the medical literature for over 50 years. These abnormalities include changes in rhythm, QRS axis, and morphology, particularly in the QRS and T waves. Such findings may reflect hemodynamic changes, such as right heart strain, as well as myocardial ischemia associated with the disease. Although certain findings may correlate with the severity of pulmonary embolism, the overall utility of the electrocardiogram is limited due to the variable presence, frequency, and transient nature of most of the abnormalities associated with the disease.     

Therapeutic approach to acute pulmonary embolism

Many therapeutic aspects of venous thromboembolism continue to generate controversy so that the general therapeutic guidelines given below are only indicative. The first step is the diagnosis of venous thromboembolism; this is done in the vast majority of patients by visualization of blood clots using either pulmonary angiography or phlebography. The second step is to arrest the thrombotic process; the best means of doing this is to administer IV heparin. In the case of contra-indication or documented inefficacy of heparin therapy, the only therapeutic solution is to interrupt the inferior vena cava either with a clip, an umbrella or a filter. The blood clot lysis, which represents the third step, is effected by the natural fibrinolytic system. Thrombolytics, administered as a bolus of urokinase (15000 CTA U/kg), are indicated in cases of life-threatening pulmonary emboli, i.e. those with a pulmonary vascular obstruction of more than 50% and with hypotension, shock, or acute right ventricular failure. The use of thrombolytics is more questionable when they are administered to improve the quality of vascular patency. The only indication for pulmonary embolectomy is a contra-indication or inefficacy of thrombolytics. Due to the diagnostic and therapeutic difficulties, the first and most important part of the treatment of pulmonary emboli must be the broad application of prophylaxis treatment in patients with a high risk of venous thromboembolism.     

Early recognition of pulmonary embolism: the key to lowering mortality

Pulmonary embolism is a major cause of morbidity and mortality in the United States. The majority of deaths from pulmonary embolism occur because an accurate diagnosis was not made. It is imperative for clinicians to have a high level of clinical suspicion of pulmonary embolism when patients present with dyspnea, tachypnea, chest pain, hemoptysis, and cough. If pulmonary embolism is diagnosed and treatment initiated, death and recurrence of embolism are uncommon. Beyond correct diagnosis and treatment, the single most effective strategy that can be employed to decrease the high mortality associated with pulmonary embolism is identification of individuals at risk and the institution of prophylactic measures. This article reviews the incidence, risk factors, assessment, physical examination, laboratory, and diagnostic testing for pulmonary embolism.     

Diagnosing pulmonary thromboembolic disease

Of the diagnostic procedures used in studying patients for pulmonary embolism, only pulmonary scintigraphy (perfusion or combined ventilation-perfusion scanning) and pulmonary angiography give direct information concerning integrity of blood vessels. The most informative single examination is pulmonary angiography, but scanning should be done first.     

Hemodynamic consequences of pulmonary embolism: reply to a rebuttal

See also Baglin T. Fifty per cent of patients with pulmonary embolism can be treated as outpatients. J Thromb Haemost 2010; 8: 2404–5; Girard P. Hemodynamic consequences of pulmonary embolism: a rebuttal. This issue, pp 412–3.     

Diagnosis of pulmonary embolism: Following the evidence from suspicion to certainty

Accurate, timely and cost-effective identification of pulmonary embolism remains a diagnostic challenge. This article reviews the pulmonary embolism diagnostic process with a focus on the best practice advice from the American College of Physicians. Benefits and risks of each diagnostic step are discussed. Emerging diagnostic tools, not included in the algorithm, are briefly reviewed.