Low Pretest Probability Of Pulmonary Embolism Research Articles

Case Report of Pulmonary Embolism with Right Ventricular Strain in a Young Female

Acute pulmonary embolism (PE) is when one or more thrombus travel to the lungs and obstruct the pulmonary artery or one of the branches of the pulmonary tree, producing signs and symptoms immediately after the obstruction. Saddle pulmonary embolism (SPE) is a rare type of acute PE that can lead to hemodynamic instability and death. The incidence of pulmonary embolism increases with age. In women, the risk of PE increases with pregnancy, hormonal contraceptives, and hormone replacement therapy. In this case, the patient was in her forties and presented with a sudden episode of continuous dyspnea that worsened over four hours. The dyspnea was associated with palpitations and diaphoresis. The clinical scoring tools had a low pre-test probability for PE. The patient had no risk factors for PE other than being obese. Significant laboratory workup showed troponin of 0.10, D-dimer of 8.10, and a B-type natriuretic peptide (BNP) of 1,160. Her computed tomography angiography (CTA) showed extensive pulmonary emboli in the bilateral main and segmental pulmonary arteries, with findings consistent with right heart strain. The patient was managed with an unfractionated heparin loading dose in the ED based on her weight, followed by a heparin drip. Then, the patient was transferred to a tertiary medical center for further interventions. Prompt recognition and treatment of a submassive PE are fundamental to improving patient mortality and morbidity.

Computed tomography for suspected pulmonary embolism results in a large number of non-significant incidental findings and follow-up investigations

Computed tomographic pulmonary angiograms (CTPAs) are often ordered to evaluate pulmonary embolism (PE) in the emergency department (ED). The increase use of CTPA has led to an increase in incidental findings, often of low clinical significance. Our objectives were to (1) assess the prevalence and clinical significance of incidental findings identified in patients evaluated with CTPAs for PE in the ED, (2) evaluate follow-up investigations for these incidental findings, and (3) assess the utility of routine chest X-rays done prior to CTPA. This is a historical cohort study of adult patients, presenting to two tertiary care EDs from January-December 2015, evaluated with CTPA for possible PE. Two reviewers' extracted data from electronic CT records in a standardized fashion with inter-rater reliability reported using the kappa statistic. We measured the prevalence of PE and stratified non-PE findings according to alternative diagnoses and incidental findings. Data were reported as mean and standard deviation (SD). Univariate analyses were performed with t test for continuous variables. A total of 1708 studies were included (mean 62years (SD 16.7), 56.9% female). PE was found in 233 (13.6%) patients. A total of 223 (13.1%) patients had an incidental finding, the majority of which included pulmonary nodules (n = 83, 37.2%) and adenopathy (n = 26, 11.6%). Of the incidental findings, 197 (88.3%) were non-significant and led to no definitive diagnosis of cancer. In patients who underwent both CTPA and chest X-ray, X-ray reports revealed the same diagnosis in 77% of PE-negative patients without missing a clinically significant incidental finding. Incidental findings are as common as a diagnosis of PE in patients undergoing CTPA. They are rarely clinically significant. Chest radiograph remains a reasonable initial investigation as it can aid in identifying alternative diagnoses especially in the setting of a low pre-test probability for PE.

Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians.

Pulmonary embolism (PE) can be a severe disease and is difficult to diagnose, given its nonspecific signs and symptoms. Because of this, testing patients with suspected acute PE has increased dramatically. However, the overuse of some tests, particularly computed tomography (CT) and plasma d-dimer measurement, may not improve care while potentially leading to patient harm and unnecessary expense. The literature search encompassed studies indexed by MEDLINE (1966-2014; English-language only) and included all clinical trials and meta-analyses on diagnostic strategies, decision rules, laboratory tests, and imaging studies for the diagnosis of PE. This document is not based on a formal systematic review, but instead seeks to provide practical advice based on the best available evidence and recent guidelines. The target audience for this paper is all clinicians; the target patient population is all adults, both inpatient and outpatient, suspected of having acute PE. Clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered. Clinicians should not obtain d-dimer measurements or imaging studies in patients with a low pretest probability of PE and who meet all Pulmonary Embolism Rule-Out Criteria. Clinicians should obtain a high-sensitivity d-dimer measurement as the initial diagnostic test in patients who have an intermediate pretest probability of PE or in patients with low pretest probability of PE who do not meet all Pulmonary Embolism Rule-Out Criteria. Clinicians should not use imaging studies as the initial test in patients who have a low or intermediate pretest probability of PE. Clinicians should use age-adjusted d-dimer thresholds (age×10 ng/mL rather than a generic 500 ng/mL) in patients older than 50 years to determine whether imaging is warranted. Clinicians should not obtain any imaging studies in patients with a d-dimer level below the age-adjusted cutoff. Clinicians should obtain imaging with CT pulmonary angiography (CTPA) in patients with high pretest probability of PE. Clinicians should reserve ventilation-perfusion scans for patients who have a contraindication to CTPA or if CTPA is not available. Clinicians should not obtain a d-dimer measurement in patients with a high pretest probability of PE.

Lung scintigraphy in the diagnosis of pulmonary embolism: current methods and interpretation criteria in clinical practice.

BackgroundIn current clinical practice lung scintigraphy is mainly used to exclude pulmonary embolism (PE). Modified diagnostic criteria for planar lung scintigraphy are considered, as newer scitigraphic methods, especially single photon emission computed tomography (SPECT) are becoming more popular.Patients and methods.Data of 98 outpatients who underwent planar ventilation/perfusion (V/Q) scintigraphy and 49 outpatients who underwent V/Q SPECT from the emergency department (ED) were retrospectively collected. Planar V/Q images were interpreted according to 0.5 segment mismatch criteria and revised PIOPED II criteria and perfusion scans according to PISA-PED criteria. V/Q SPECT images were interpreted according to the criteria suggested in EANM guidelines. Final diagnosis of PE was based on the clinical decision of an attending physician and evaluation of a 12 months follow-up period.ResultsUsing 0.5 segment mismatch criteria and revised PIOPED II, planar V/Q scans were diagnostic in 93% and 84% of cases, respectively. Among the diagnostic planar scans readings specificity for 0.5 segment mismatch criteria was 98%, and 99% for revised PIOPED II criteria. V/Q SPECT showed a sensitivity of 100% and a specificity of 98%, without any non-diagnostic cases. In patients with low pretest probability for PE, planar V/Q scans assessed by 0.5 segment mismatch criteria were diagnostic in 92%, and in 85% using revised PIOPED II criteria, while perfusion scintigraphy without ventilation scans was diagnostic in 80%.ConclusionsLung scintigraphy yielded diagnostically definitive results and is reliable in ruling out PE in patients from ED. V/Q SPECT has excellent specificity and sensitivity without any non-diagnostic results. Percentage of non-diagnostic results in planar lung scintigraphy is considerably smaller when 0.5 segment mismatch criteria instead of revised PIOPED II criteria are used. Diagnostic value of perfusion scintigraphy according to PISA-PED criteria is inferior to combined V/Q scintigraphy; the difference is evident especially in patients with low pretest probability for PE.

Evaluation of Pulmonary Embolism in the Emergency Department and Consistency With a National Quality Measure

The National Quality Forum (NQF) has endorsed a performance measure designed to increase imaging efficiency for the evaluation of pulmonary embolism (PE) in the emergency department (ED). To our knowledge, no published data have examined the effect of patient-level predictors on performance. To quantify the prevalence of avoidable imaging in ED patients with suspected PE, we performed a prospective, multicenter observational study of ED patients evaluated for PE from 2004 through 2007 at 11 US EDs. Adult patients tested for PE were enrolled, with data collected in a standardized instrument. The primary outcome was the proportion of imaging that was potentially avoidable according to the NQF measure. Avoidable imaging was defined as imaging in a patient with low pretest probability for PE, who either did not have a D-dimer test ordered or who had a negative D-dimer test result. We performed subanalyses testing alternative pretest probability cutoffs and imaging definitions on measure performance as well as a secondary analysis to identify factors associated with inappropriate imaging. χ(2) Test was used for bivariate analysis of categorical variables and multivariable logistic regression for the secondary analysis. We enrolled 5940 patients, of whom 4113 (69%) had low pretest probability of PE. Imaging was performed in 2238 low-risk patients (38%), of whom 811 had no D-dimer testing, and 394 had negative D-dimer test results. Imaging was avoidable, according to the NQF measure, in 1205 patients (32%; 95% CI, 31%-34%). Avoidable imaging owing to not ordering a D-dimer test was associated with age (odds ratio [OR], 1.15 per decade; 95% CI, 1.10-1.21). Avoidable imaging owing to imaging after a negative D-dimer test result was associated with inactive malignant disease (OR, 1.66; 95% CI, 1.11-2.49). One-third of imaging performed for suspected PE may be categorized as avoidable. Improving adherence to established diagnostic protocols is likely to result in significantly fewer patients receiving unnecessary irradiation and substantial savings.

Rarity of isolated pulmonary embolism and acute aortic syndrome occurring outside of the field of view of dedicated coronary CT angiography

Although triple rule-out CT angiography (TRO) to simultaneously evaluate acute coronary syndrome (ACS), pulmonary embolism (PE), and acute aortic syndrome (AAS) is increasingly used in many institutions, TRO is inevitably associated with increased radiation exposure due to extended z-axis coverage compared with dedicated coronary CT angiography (DCTA). To determine the frequency of exclusion of findings of AAS, PE, and significant incidental non-cardiac pathology that may be the cause of acute chest pain when using a restricted DCTA field of view (FOV). We retrospectively reviewed CT images and charts of 103 patients with acute PE and 50 patients with AAS. Either non-ECG gated dedicated pulmonary or aortic CT angiography was performed using 16- or 64-slice multidetector CT (MDCT). We analyzed the incidence of isolated PE, AAS, or significant non-cardiac pathology outside of DCTA FOV (i.e. from tracheal carina to the base of heart). There were two cases of isolated PE (2/103, 1.9%) excluded from the FOV of DCTA. One case of PE was isolated to the subsegmental pulmonary artery in the posterior segment of the right upper lobe. In the second case, pulmonary embolism in the left main pulmonary artery was located out of the FOV of DCTA because the left main pulmonary artery was retracted upwardly by fibrotic scar in the left upper lobe due to prior tuberculosis. There was no case of AAS and significant non-cardiac pathology excluded from the FOV of DCTA. AAS (n = 50) consisted of penetrating atherosclerotic ulcer (n = 7), intramural hematoma (n = 5) and aortic dissection (n = 38). As isolated PE, AAS, and significant non-cardiac pathology outside of the DCTA FOV rarely occur, DCTA may replace TRO in the evaluation of patients with non-specific acute chest pain and a low pre-test probability of PE or aortic dissection.

Comparison of the Unstructured Clinician Estimate of Pretest Probability for Pulmonary Embolism to the Canadian Score and the Charlotte Rule: A Prospective Observational Study

Clinical decision rules have been validated for estimation of pretest probability in patients with suspected pulmonary embolism (PE). However, many clinicians prefer to use clinical gestalt for this purpose. The authors compared the unstructured clinical estimate of pretest probability for PE with two clinical decision rules. This prospective, observational study was conducted from October 2001 to July 2004 at an urban academic emergency department with an annual census of 105,000. A total of 2,603 patients were enrolled; mean age (+/- SD) was 45 (+/- 16) years, and 70% were female. All patients were evaluated for PE using a previously published protocol, including D-dimer and alveolar dead space measurements, and selected use of pulmonary vascular imaging. All had 45-day follow-up. Interobserver agreement for each pretest probability estimation method was measured in a separate group of 154 patients. The overall prevalence of PE was 5.8% (95% confidence interval [CI] = 4.9% to 6.8%). Most were deemed low risk for PE, including 69% by the unstructured estimate < 15%, 73% by the Canadian score < 2, and 88% by the Charlotte rule "safe." The corresponding prevalence of disease in each of these low-risk groups was 2.6%, 3.0%, and 4.2%. Weighted Cohen's kappa values were 0.60 (95% CI = 0.46 to 0.74) for the unstructured clinical estimate < 15%, 0.47 (95% CI = 0.33 to 0.61) for the Canadian score < 2, and 0.85 (95% CI = 0.69 to 1.0) for the Charlotte rule "safe." The unstructured clinical estimate of low pretest probability for PE compares favorably with the Canadian score and the Charlotte rule. Interobserver agreement for the unstructured estimate is moderate.