Brief cardiovascular imaging with pocket-size ultrasound devices improves the accuracy of the initial assessment of suspected pulmonary embolism

Pulmonary embolism onset is frequently neglected due to the non-specific character of its symptoms. Pocket-size imaging devices (PSID) present an opportunity to implement imaging diagnostics into conventional physical examination. The aim of this study was to test the hypothesis that supplementation of the initial bedside assessment of patients with suspected pulmonary embolism (PE) with four-point compression venous ultrasonography (CUS) and right ventricular size assessment with the use of PSID equipped with dual probe could positively influence the accuracy of clinical predictions. A single-centre, prospective analysis was conducted on 100 patients (47 men, mean age 68?±?13 years) with suspected PE. Clinical assessment on the basis of Wells and revised Geneva score and physical examination were supplemented with CUS and RV measurements by PSID. The mean time of PSID scanning was 4.9?±?0.8 min and was universally accepted by the patients. Fifteen patients had deep venous thrombosis and RV enlargement was observed in 59 patients. PE was confirmed in 24 patients. If the both CUS was positive and RV enlarged, the specificity was 100% and sensitivity 54%, ROC AUC 0.771 [95% CI 0.68–0.85]. The Wells rule within our study population had the specificity of 86% and sensitivity of 67%, ROC AUC 0.776 (95% CI 0.681–0.853, p?<?0.0001). Similar values calculated for the revised Geneva score were as follows: specificity 58% and sensitivity 63%, ROC AUC 0.664 (95% CI 0.563–0.756, p?=?0.0104). Supplementing the revised Geneva score with additional criteria of CUS result and RV measurement resulted in significant improvement of diagnostic accuracy. The difference between ROC AUCs was 0.199 (95% Cl 0.0893–0.308, p?=?0.0004). Similar modification of Wells score increased ROC AUC by 0.133 (95% CI 0.0443–0.223, p?=?0.0034). Despite the well-acknowledged role of the PE clinical risk assessment scores the diagnostic process may benefit from the addition of basic bedside ultrasonographic techniques.     

The use of D-dimer testing and Wells score in patients with high probability for acute pulmonary embolism

Rationale, aims and objective  To investigate if a combination of Wells pre-test probability score and D-dimer testing could be used as a safe base for making clinical decisions on further investigations for patients with intermediate to high risks of pulmonary embolism (PE).
Methods  One hundred and twenty patients with signs or symptoms of acute PE were investigated with pulmonary angiography (PA) or contrast enhanced computed tomography of the pulmonary arteries (CTPA), D-dimer testing (Tinaquant^®) and clinical scoring using the Wells pre-test probability score during their first 48 hours at the hospital. Patients were recruited consecutively from emergency departments at two teaching hospitals.
Results  The cut-off value of 0.5 mg L⁻¹ in D-dimer analysis is proved adequate with a negative predictive value (NPV) of 92% in this group of patients with intermediate to high risks. The combination of D-dimer testing and Wells score increases the NPV to 94%. The specificities of both tests were low.
Conclusion  D-dimer and Wells pre-test probability scores are safe to rule out acute PE even in patients with at least an intermediate risk of PE, but the specificity is low. D-dimer testing had a higher NPV than Wells score and the combination improved the algorithm further. The cut-off level for a high risk of PE measured with the Wells score was four and it seems reasonable to use that cut-off level in future algorithms. In addition, both PA and CTPA can present false positive and negative results difficult to interpret.     

Clinical probability score and D-dimer estimation lack utility in the diagnosis of childhood pulmonary embolism

Summary.  Background : Childhood pulmonary embolism (PE) causes significant mortality and evidence suggests that it is under-diagnosed. Clinical probability scores and D-dimer estimation to assess pre-test probability have not been studied in children with suspected PE. Patients/Methods : This retrospective cohort study evaluated Wells simplified probability score for PE in 50 children with PE and 25 PE negative control patients, and D-dimer values in 27 PE positive and 12 PE negative children. Results : PE positive and PE negative groups had similar rates of risk factors for venous thromboembolism (VTE). Wells simplified probability score showed a small difference between PE positive and PE negative children (median score: PE positive, 4.5; PE negative, 4; P  =   0.009), children with PE are more likely to obtain a 'PE likely' score (score > 4), P  =   0.012. The difference was of slightly greater significance when the Wells score was adjusted to account for pediatric normal ranges for heart rate, P  =   0.007, and signs/symptoms of upper limb DVT, P  =   0.006. Children with PE were as likely as PE negative patients to have a D-dimer value within the normal range (PE positive, 15%; PE negative, 25%; P  =   0.654). A combination of a 'PE unlikely' score and normal D-dimer value occurred in 1/12 (8%) of PE negative children. Conclusions : The Wells clinical probability score and D-dimer estimation may lack utility in the determination of pre-test probability of PE in children. Validation of a pediatric clinical probability score, incorporating D-dimer estimation, by prospective study, would be difficult as a result of the rarity of childhood PE.     

肺栓塞36例急诊误诊临床分析

目的提高急诊科医生对肺血栓栓塞（pulmonary thromboembolism,FFE）的认识,探索急诊可行的PrE诊断程序．以提高本病早期确诊率。方法回顾性分析近5年来我院急诊误诊的36例FTE的临床资料,并进行改良Geneva评分评估临床诊断可能性。结果本组36例误诊为心血管疾病25例（69．4％）,误诊为其他呼吸系统疾病9例（25％）,误诊为脑血管疾病2例（5．6％）,其中30例（83．3％）有易患因素。进行改良Geneva评分显示FFE中度可能性26例,低度可能性10例。查D-二聚体36例均升高,后经螺旋CT肺动脉造影（CTPA）确诊32例、肺通气灌注扫描确诊4例,均予抗凝治疗好转出院。结论PTE临床易误漏诊,急诊科医生应加强对奉病的认识,接诊PTE疑诊患者应洵刚有尤易患因索,通过改良Geneva评分进行诊断可能性评估,结合血D-二聚体检测,必要时臼丁行CTFA等,以提高确诊率。     

Clinical prediction rules for pulmonary embolism: a systematic review and meta‐analysis

Summary. Background: Pretest probability assessment is necessary to identify patients in whom pulmonary embolism (PE) can be safely ruled out by a negative D‐dimer without further investigations. Objective:   Review and compare the performance of available clinical prediction rules (CPRs) for PE probability assessment. Patients/methods: We identified studies that evaluated a CPR in patients with suspected PE from Embase, Medline and the Cochrane database. We determined the 95% confidence intervals (CIs) of prevalence of PE in the various clinical probability categories of each CPR. Statistical heterogeneity was tested. Results: We identified 9 CPR and included 29 studies representing 31215 patients. Pooled prevalence of PE for three‐level scores (low, intermediate or high clinical probability) was: low, 6% (95% CI, 4–8), intermediate, 23% (95% CI, 18–28) and high, 49% (95% CI, 43–56) for the Wells score; low, 13% (95% CI, 8–19), intermediate, 35% (95% CI, 31–38) and high, 71% (95% CI, 50–89) for the Geneva score; low, 9% (95% CI, 8–11), intermediate, 26% (95% CI, 24–28) and high, 76% (95% CI, 69–82) for the revised Geneva score. Pooled prevalence for two‐level scores (PE likely or PE unlikely) was 8% (95% CI,6–11) and 34% (95% CI,29–40) for the Wells score, and 6% (95% CI, 3–9) and 23% (95% CI, 11–36) for the Charlotte rule. Conclusion: Available CPR for assessing clinical probability of PE show similar accuracy. Existing scores are, however, not equivalent and the choice among various prediction rules and classification schemes (three‐ versus two‐level) must be guided by local prevalence of PE, type of patients considered (outpatients or inpatients) and type of D‐dimer assay applied.     

The pulmonary embolism rule‐out criteria (PERC) rule does not safely exclude pulmonary embolism

Summary. Background: The Pulmonary Embolism Rule‐out Criteria (PERC) rule is a clinical diagnostic rule designed to exclude pulmonary embolism (PE) without further testing. We sought to externally validate the diagnostic performance of the PERC rule alone and combined with clinical probability assessment based on the revised Geneva score. Methods: The PERC rule was applied retrospectively to consecutive patients who presented with a clinical suspicion of PE to six emergency departments, and who were enrolled in a randomized trial of PE diagnosis. Patients who met all eight PERC criteria [PERC_(?)] were considered to be at a very low risk for PE. We calculated the prevalence of PE among PERC_(?) patients according to their clinical pretest probability of PE. We estimated the negative likelihood ratio of the PERC rule to predict PE. Results: Among 1675 patients, the prevalence of PE was 21.3%. Overall, 13.2% of patients were PERC_(?). The prevalence of PE was 5.4% [95% confidence interval (CI): 3.1–9.3%] among PERC_(?) patients overall and 6.4% (95% CI: 3.7–10.8%) among those PERC_(?) patients with a low clinical pretest probability of PE. The PERC rule had a negative likelihood ratio of 0.70 (95% CI: 0.67–0.73) for predicting PE overall, and 0.63 (95% CI: 0.38–1.06) in low‐risk patients. Conclusions: Our results suggest that the PERC rule alone or even when combined with the revised Geneva score cannot safely identify very low risk patients in whom PE can be ruled out without additional testing, at least in populations with a relatively high prevalence of PE.     

Clinical experience and pre-test probability scores in the diagnosis of pulmonary embolism

BACKGROUND: The Geneva and Wells pre-test probability scores are intended to replace empirical assessment of patients with suspected pulmonary embolism (PE). The effect of clinical experience on the inter-rater variability of these scores, and on empirical judgement, is unknown. AIM: To determine whether medical staff appointment grade affects the inter-rater variability of these pre-test probability scores, or empirical assessment, in patients with suspected PE. DESIGN: Questionnaire survey. METHODS: Doctors were grouped by grade (mean number of years since graduation+/-SEM): house officers 0.7+/-0.2, registrars 6.3+/-0.6, consultants 25+/-4 and applied pre-test probability scores to actual case scenarios. RESULTS: The Geneva score was the most consistent method of determining pre-test probability and was unaffected by clinical experience (Geneva kappa=0.73, Wells kappa=0.38, empirical kappa=0.23, p<0.001 ). With empirical judgement, inter-rater variability was inversely proportional to clinical experience (house officers kappa=0.37, registrars kappa=0.24, consultants kappa= 0.16, p<0.05). DISCUSSION: The Geneva score was the least variable method and can be applied by junior or senior doctors. Using empirical judgement, junior doctors were more likely to agree on the pre-test probability of PE than were their more senior colleagues. This may imply that as physicians gain experience, they recognize that the diagnosis of PE can be difficult to assess and are reluctant to exclude it on clinical grounds.     

Outcomes of high pretest probability patients undergoing d-dimer testing for pulmonary embolism: a pilot study

ELISA (enzyme-linked immunosorbent assay) D-dimer testing is commonly used in the evaluation of possible pulmonary embolism (PE) in the emergency department, but is not recommended in high pretest probability patients. Whether a negative ELISA D-dimer can safely rule out PE in these patients is not known, as there have been no large studies comparing ELISA D-dimer results and outcomes in high pretest probability patients. This was a prospective observational pilot study of emergency department patients evaluated for PE. Patients evaluated for PE had pretest probability assessed by the Wells PE Score. High pretest probability was defined as: dichotomized Wells Score > 4 points and patients with trichotomized Wells Score > 6 points. Patients had an ELISA D-dimer ordered by the treating physician. Pulmonary embolism was defined as: positive computed tomography scan, high probability ventilation/perfusion scan, positive pulmonary angiogram, or PE on 3-month follow-up. We calculated sensitivity, specificity, positive and negative predictive value, and likelihood ratios for the ELISA D-dimer. We prospectively enrolled 541 patients who underwent D-dimer testing for PE, of whom 130 patients had Wells Score > 4 and 33 patients had Wells Score > 6 (not mutually exclusive). Of subjects with Wells Score > 4, 23 (18%) were diagnosed with PE and 40 (31%) had a negative D-dimer. No patient with Wells Score > 4 (sensitivity 100%, 95% confidence interval [CI] 82%–100%; specificity 37%, 95% CI 28%–47%) or Wells Score > 6 (sensitivity 100%, 95% CI 63%–100%; specificity 56%, 95% CI 35%–76%) who had a negative D-dimer was diagnosed with PE. The likelihood ratio for a negative D-dimer was 0 for both the Wells > 4, and Wells > 6 groups, however, the upper limits of the confidence interval around the post-test probability for PE were 16% and 33%, respectively, for these high probability groups. In this pilot study, the rapid ELISA D-dimer had high sensitivity and negative predictive value even when applied to patients with high pretest probability for PE. However, with the post-test probability of PE still as high as 16–33% in the negative D-dimer groups, this precludes applying the results to patient care at present. Further testing is warranted to determine whether these findings can be safely incorporated into practice.     

Automated Pulmonary Embolism Risk Classification and Guideline Adherence for Computed Tomography Pulmonary Angiography Ordering

Background

The assessment of clinical guideline adherence for the evaluation of pulmonary embolism (PE) via computed tomography pulmonary angiography (CTPA) currently requires either labor‐intensive, retrospective chart review or prospective collection of PE risk scores at the time of CTPA order. The recording of clinical data in a structured manner in the electronic health record (EHR) may make it possible to automate the calculation of a patient's PE risk classification and determine whether the CTPA order was guideline concordant.

Objectives

The objective of this study was to measure the performance of automated, structured data–only versions of the Wells and revised Geneva risk scores in emergency department (ED) encounters during which a CTPA was ordered. The hypothesis was that such an automated method would classify a patient's PE risk with high accuracy compared to manual chart review.

Methods

We developed automated, structured data–only versions of the Wells and revised Geneva risk scores to classify 212 ED encounters during which a CTPA was performed as “PE likely” or “PE unlikely.” We then combined these classifications with D‐dimer ordering data to assess each encounter as guideline concordant or discordant. The accuracy of these automated classifications and assessments of guideline concordance were determined by comparing them to classifications and concordance based on the complete Wells and revised Geneva scores derived via abstractor manual chart review.

Results

The automatically derived Wells and revised Geneva risk classifications were 91.5 and 92% accurate compared to the manually determined classifications, respectively. There was no statistically significant difference between guideline adherence calculated by the automated scores compared to manual chart review (Wells, 70.8% vs. 75%, p = 0.33; revised Geneva, 65.6% vs. 66%, p = 0.92).

Conclusion

The Wells and revised Geneva score risk classifications can be approximated with high accuracy using automated extraction of structured EHR data elements in patients who received a CTPA. Combining these automated scores with D‐dimer ordering data allows for the automated assessment of clinical guideline adherence for CTPA ordering in the ED, without the burden of manual chart review.

     

Pulmonary embolism and COVID-19: A comparative analysis of different diagnostic models performance

ObjectivePulmonary embolism (PE) is a common complication of SARS-CoV-2 infection. Several diagnostic prediction rules based on pretest probability and D-dimer have been validated in non-COVID patients, but it remains unclear if they can be safely applied in COVID-19 patients. We aimed to compare the diagnostic accuracy of the standard approach based on Wells and Geneva scores combined with a standard D-dimer cut-off of 500 ng/mL with three alternative strategies (age-adjusted, YEARS and PEGeD algorithms) in COVID-19 patients.MethodsThis retrospective study included all COVID-19 patients admitted to the Emergency Department (ED) who underwent computed tomography pulmonary angiography (CTPA) due to PE suspicion. The diagnostic prediction rules for PE were compared between patients with and without PE.ResultsWe included 300 patients and PE was confirmed in 15%. No differences were found regarding comorbidities, traditional risk factors for PE and signs and symptoms between patients with and without PE. Wells and Geneva scores showed no predictive value for PE occurrence, whether a standard or an age-adjusted cut-off was considered. YEARS and PEGeD algorithms were associated with increased specificity (19% CTPA reduction) but raising non-diagnosed PE. Despite elevated in all patients, those with PE had higher D-dimer levels. However, incrementing thresholds to select patients for CTPA was also associated with a substantial decrease in sensitivity.ConclusionNone of the diagnostic prediction rules are reliable predictors of PE in COVID-19. Our data favour the use of a D-dimer threshold of 500 ng/mL, considering that higher thresholds increase specificity but limits this strategy as a screening test.     

急诊床边超声对修正的Geneva评分中度患者肺栓塞的预测价值

目的回顾性分析急诊床边超声在修正的Geneva评分低中高度患者肺栓塞的诊断价值,减少肺栓塞误诊漏诊,提高肺栓塞的早期诊断率。方法收集1999—2010年10月本院可疑肺栓塞112例,其中临床确诊肺栓塞75例,分析修正的Geneva评分及超声结果。据修正的Geneva评分分为低、中、高危组,每组分为超声阳性与超声阴性对照组,分别计数确诊肺栓塞与非肺栓塞人数,SPSS 15.0软件进行统计分析,计数资料组间比较采用卡方检验或FISHER精确概率法分析,以P<0.05为差异具有统计学意义。结果肺栓塞可能性分别与Geneva评分(χ2=38.6862.P<0.0001)高低有关,具有统计学意义。超声阳性与超声阴性对照组分别对应的肺栓塞与非肺栓塞人数在Ge-neva评分低组(P=0.2120)及高组(P=1.0000)无统计学意义,在中组超声阳性确诊肺栓塞的可能性大于超声阴性,(P=0.0235)有统计学意义。结论修正的Geneva评分中度患者床边超声检查可增加确诊肺栓塞的可能性,减少肺栓塞误漏诊,提高肺栓塞的早期诊断率。     

The utility of pretest probability assessment in patients with clinically suspected venous thromboembolism

Summary.  The assessment of pretest probability (PTP), with stratification into low-, intermediate- and high-risk groups is an essential initial step in the current diagnostic management of patients with suspected venous thromboembolism (VTE). In combination with additional information, it reduces the need for initial and supplementary imaging, and allows considerable refinement of the posterior probability of VTE following non-invasive imaging. PTP may be assessed either empirically or by using various decision rules or scoring systems, the best known of which are the simplified Wells scores for suspected deep vein thrombosis (DVT) and pulmonary embolism (PE), and the Geneva score for suspected PE. Each of these approaches shows similar directional and categorical accuracy, and has been validated as facilitating clinically useful classification of the PTP, although an overview of data suggests that fewer patients tend to be classified as low PTP when assessed empirically. This group is the most important to identify, as several outcome studies have shown that imaging and treatment are safely obviated in outpatients with suspected DVT or PE who have a low PTP in combination with negative d -dimer testing, a subgroup accounting for up to half of all patients studied. Hence, while probably not of critical importance, the explicit approach offered by scoring systems might be preferred over empirical assessment, particularly when used by more junior staff.     

Safety of the pulmonary embolism rule-out criteria rule: Findings from the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry

Background

The diagnostic strategy for pulmonary embolism (PE) includes a D-dimer test when PE probability is low or intermediate, but false-positive D-dimer results are frequent and can result in an unnecessary computed tomography pulmonary angiogram. The PE rule-out criteria (PERC) rule excludes PE without D-dimer testing when pretest probability is <15%. The aim of this study was to assess the safety of the PERC rule strategy in patients included in the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry.

Methods

This retrospective cohort study used data from the RIETE registry, an ongoing, international prospective registry of patients with objectively confirmed venous thromboembolism. The primary outcome was the failure rate of the PERC strategy, represented by the proportion of PERC-negative (PERC-N) patients with a PE included in the registry. Secondary outcomes were a comparison of the clinical characteristics, treatment strategy, and outcome of PERC-N versus PERC-positive (PERC-P) patients at 3 months.

Results

From 2001 to 2021, a total of 49,793 patients with acute PE were enrolled in the RIETE registry. We included 48,903 in the final analysis after exclusion of 890 patients with an undetermined PERC status. Only 346 patients were PERC-N with a failure rate of 0.7% (95% confidence interval 0.6%–0.8%). PERC-N patients presented more frequently with chest pain but less often with dyspnea, syncope, or hypotension. They also had subsegmental or segmental PE more frequently, were more often treated with direct oral anticoagulants, and received mechanical or pharmacological thrombolysis less often. In addition, PERC-N patients had a lower incidence of recurrent deep vein thrombosis, major bleeding, and death attributed to PE during the 3-month follow-up.

Conclusions

A low failure rate of the PERC rule was observed in the RIETE registry, thus supporting its use to safely identify patients with an unlikely probability of PE.     

D-dimer testing is useful to exclude deep vein thrombosis in elderly outpatients

Summary.  Background:  Deep vein thrombosis (DVT) can be safely and reliably excluded in patients with a low clinical probability and a negative D-dimer result but the accuracy and utility of such a strategy is unclear in elderly patients. Objectives:  We sough to compare the performance of the Wells pretest probability (PTP) model and D-dimer testing between patients of different age groups and to examine the utility of the two PTP model classification schemes (low/moderate/high vs. unlikely/likely) in excluding DVT in elderly outpatients. Patients/Methods:  Pooled analysis of databases from three prospective diagnostic studies evaluating consecutive outpatients with suspected DVT. Results:  A total of 2696 patients were evaluated. DVT was diagnosed in 400 (15%) patients overall and in 50 out of 325 (15.5%) patients ≥ 60 years old. The PTP distribution and the prevalence of DVT in each PTP category were similar among the different age groups. The negative predictive values of a low or unlikely PTP score in combination with a negative D-dimer result were 99% for all groups. A negative D-dimer in combination with a low or unlikely PTP excluded 21.7% and 31% of patients ≥ 80 years old, respectively. Conclusions:  The combination of a low or unlikely PTP with a negative D-dimer result can effectively and safely exclude DVT in a significant proportion of elderly outpatients. However, this clinical prediction rule needs to be prospectively validated with different D-dimer assays in this specific population.     

Sixteen-Year-old Athlete with Chest Pain and Shortness of Breath due to Pulmonary Emboli

Background

Pulmonary embolism (PE) is a life-threatening condition that is extremely uncommon in the healthy pediatric population.

Objective

Because pediatric PE is rarely on the Emergency Physician's differential diagnosis, with this case we hope to increase the clinical suspicion for PE in children who present to the Emergency Department (ED).

Case Report

This is a case of bilateral pulmonary embolism in a 16-year-old basketball player whose only risk factor is oral contraceptive medication. Initial vital signs demonstrated a temperature of 37.1°C (98.8°F), blood pressure 124/74 mm Hg, heart rate 74 beats/min, respiratory rate 16 breaths/min, and oxygen saturation 100% on room air. Subsequent vital signs, physical examination, chest radiograph, electrocardiogram, and laboratory assessments were all within normal limits. Using clinician gestalt in combination with the patient's Wells score of 0, a D-dimer was obtained and returned at 1916 ng/mL. The computed tomography scan with PE protocol detected a total of seven pulmonary emboli bilaterally. The patient was anticoagulated with Lovenox (Sanofi US, Bridgewater, NJ) in the ED and admitted to the pediatric intensive care unit. Complete thrombophilia work-up was negative. The patient was discharged with Lovenox and was transitioned to warfarin.

Conclusions

Emergency Physicians may be inclined to discharge a pediatric patient at low pre-test probability for PE with outpatient follow-up if the work-up is non-contributory. But the current adult PE clinical criteria are not as sensitive or specific in the pediatric population. This case demonstrates that the clinician's gestalt should play a major role in combination with the Wells score and PERC (pulmonary embolism rule-out criteria) rule to exclude PE until clinical decision rules specific for the pediatric population are established.     

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

Objectives: 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. Methods: 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. Results: 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 κ 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.” Conclusions: 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.     

Ordering CT pulmonary angiography to exclude pulmonary embolism: defense versus evidence in the emergency room

Purpose

To identify reasons for ordering computed tomography pulmonary angiography (CTPA), to identify the frequency of reasons for CTPA reflecting defensive behavior and evidence-based behavior, and to identify the impact of defensive medicine and of training about diagnosing pulmonary embolism (PE) on positive results of CTPA.

Methods

Physicians in the emergency department of a tertiary care hospital completed a questionnaire before CTPA after being trained about diagnosing PE and completing questionnaires.

Results

Nine hundred patients received a CTPA during 3?years. For 328 CTPAs performed during the 1-year study period, 140 (43?%) questionnaires were completed. The most frequent reasons for ordering a CTPA were to confirm/rule out PE (93?%), elevated D-dimers (66?%), fear of missing PE (55?%), and Wells/simplified revised Geneva score (53?%). A positive answer for “fear of missing PE” was inversely associated with positive CTPA (OR 0.36, 95?% CI 0.14–0.92, p?=?0.033), and “Wells/simplified revised Geneva score” was associated with positive CTPA (OR 3.28, 95?% CI 1.24–8.68, p?=?0.017). The proportion of positive CTPA was higher if a questionnaire was completed, compared to the 2-year comparison period (26.4 vs. 14.5?%, OR 2.12, 95?% CI 1.36–3.29, p?p?=?0.067).

Conclusion

Reasons for CTPA reflecting defensive behavior—such as “fear of missing PE”—were frequent, and were associated with a decreased odds of positive CTPA. Defensive behavior might be modifiable by training in using guidelines.     

D-dimer can help differentiate suspected pulmonary embolism patients that require anti-coagulation

ObjectivesDetermine whether D-dimer concentration in the absence of imaging can differentiate patients that require anti-coagulation from patients who do not require anti-coagulation.MethodsData was obtained retrospectively from 366 hemodynamically stable adult ED patients with suspected pulmonary embolism (PE).Patients were categorized by largest occluded artery and aggregated into: ‘Require anti-coagulation’ (main, lobar, and segmental PE), ‘Does not require anti-coagulation’ (sub-segmental and No PE), ‘High risk of deterioration’ (main and lobar PE), and ‘Not high risk of deterioration’ (segmental, sub-segmental, and No PE) groups.Wilcoxon rank-sum test was used for 2 sample comparisons of median D-dimer concentrations. Receiver operating characteristic (ROC) curve analysis was utilized to determine a D-dimer cut-off that could differentiate ‘Require anti-coagulation’ from ‘Does not require anti-coagulation’ and ‘High risk of deterioration’ from ‘Low risk of deterioration’ groups.ResultsThe ‘Require anti-coagulation’ group had a maximum area under the curve (AUC) of 0.92 at an age-adjusted D-dimer cut-off of 1540 with a specificity of 86% (95% CI, 81–91%), and sensitivity of 84% (79–90%). The ‘High risk of deterioration’ group had a maximum AUC of 0.93 at an age-adjusted D-dimer cut-off of 2500 with a specificity of 90% (85–93%) and sensitivity of 83% (77–90%).ConclusionsAn age-adjusted D-dimer cut-off of 1540 ng/mL differentiates suspected PE patients requiring anti-coagulation from those not requiring anti-coagulation. A cut-off of 2500 differentiates those with high risk of clinical deterioration from those not at high risk of deterioration. When correlated with clinical outcomes, these cut-offs can provide an objective method for clinical decision making when imaging is unavailable.     

The Positive Rate of Pulmonary Embolism by CT Pulmonary Angiography Is High in an Emergency Department,Even in Low-Risk or Young Patients

ObjectiveThe clinical presentation of pulmonary embolism (PE) can be various and misleading. We analyzed patients with suspicion of PE and subsequently performed computed tomography pulmonary angiography (CTPA) in an emergency department of Internal Medicine, focusing on patient groups in which PE might be underestimated in the emergency setting, such as young patients and patients with low clinical probability.Material and MethodsIn 2016 and 2017, all patients receiving a CTPA for investigation of PE were retrospectively evaluated for clinical parameters (age, symptoms, and vital parameters) and D-dimers. The Wells score was calculated.ResultsCTPA was performed in 323 patients (158 female and 165 male; mean age 62 years). The leading symptoms for admission were dyspnea or chest pain; 62% showed intermediate or high risk for PE, calculated by applying the Wells score. In 123 (38%) of all patients, a PE was proved and pathologic age-adjusted D-dimers were found in 97.6%. Thirty of 121 (25%) patients with low risk according to Wells score had a PE. Deep vein thrombosis was verified in 67/123 (55%) patients; 43% (15/35) of all suspicions for PE in patients <40 years were positive with 4/15 (26%), showing a central PE. Younger patients (<40 years) with PE presented more often with tachycardia or tachypnea and chest pain or dyspnea than elderly patients with PE.ConclusionCTPA frequently proves a PE in patients with suspicion of PE in an emergency department of Internal Medicine. If PE is suspected and CTPA performed accordingly, the presence of PE is quite common even in low-risk patient groups (Wells score) or in young patients <40 years with chest pain or dyspnea.     

Accuracy of Very Low Pretest Probability Estimates for Pulmonary Embolism Using the Method of Attribute Matching Compared with the Wells Score

Objectives: Attribute matching matches an explicit clinical profile of a patient to a reference database to estimate the numeric value for the pretest probability of an acute disease. The authors tested the accuracy of this method for forecasting a very low probability of venous thromboembolism (VTE) in symptomatic emergency department (ED) patients. Methods: The authors performed a secondary analysis of five data sets from 15 hospitals in three countries. All patients had data collected at the time of clinical evaluation for suspected pulmonary embolism (PE). The criterion standard to exclude VTE required no evidence of PE or deep venous thrombosis (DVT) within 45 days of enrollment. To estimate pretest probabilities, a computer program selected, from a large reference database of patients previously evaluated for PE, patients who matched 10 predictor variables recorded for each current test patient. The authors compared the outcome frequency of having VTE [VTE(+)] in patients with a pretest probability estimate of <2.5% by attribute matching, compared with a value of 0 from the Wells score. Results: The five data sets included 10,734 patients, and 747 (7.0%, 95% confidence interval [CI] = 6.5% to 7.5%) were VTE(+) within 45 days. The pretest probability estimate for PE was <2.5% in 2,975 of 10,734 (27.7%) patients, and within this subset, the observed frequency of VTE(+) was 48 of 2,975 (1.6%, 95% CI = 1.2% to 2.1%). The lowest possible Wells score (0) was observed in 3,412 (31.7%) patients, and within this subset, the observed frequency of VTE(+) was 79 of 3,412 (2.3%, 95% CI = 1.8% to 2.9%) patients. Conclusions: Attribute matching categorizes over one‐quarter of patients tested for PE as having a pretest probability of <2.5%, and the observed rate of VTE within 45 days in this subset was <2.5%. ACADEMIC EMERGENCY MEDICINE 2010; 17:133–141 © 2010 by the Society for Academic Emergency Medicine