Assessment of the pulmonary embolism rule-out criteria rule for evaluation of suspected pulmonary embolism in the emergency department

Background

Overuse of resources when evaluating pulmonary embolism (PE) is a concern if the D-dimer assay is improperly used in the evaluation of emergency department patients with suspected PE. The pulmonary embolism rule-out criteria (PERC) rule was derived to prevent unnecessary diagnostic testing in this patient population. The objective of this study was to assess the PERC rule's performance in an external population.

Methods

This was a secondary analysis of a prospectively collected database comparing PERC rule variables to diagnosis of PE in consecutive patients with suspicion for PE. Bivariate analysis on individual variables and the overall accuracy of the PERC rule were performed.

Results

Patients on 120 randomly assigned shifts were enrolled with a PE prevalence of 12%. The sensitivity, specificity, positive predictive, and negative predictive values of the PERC rule were 100% (95% confidence interval [CI], 79%-100%), 16% (95% CI, 10%-24%), 14% (95% CI, 8%-14%), and 100% (95% CI, 80%-100%), respectively, for the total patient population, and 100% (95% CI, 25%-100%), 33% (95% CI, 12%-35%), 2% (95% CI, 0%-11%), and 100% (95% CI, 75%-100%), respectively, for the low pretest probability population. Bivariate analysis showed unilateral leg swelling, recent surgery, and a history of venous thromboembolic event to be predictive of the diagnosis of PE.

Conclusions

The PERC rule may identify a cohort of patients with suspected PE for whom diagnostic testing beyond history and physical examination is not indicated.     

Utilization and Yield of Chest Computed Tomographic Angiography Associated with Low Positive D-dimer Levels

Background

It is unclear to what degree broadly applied D-dimer testing combined with a low threshold for imaging with even minimally positive results may be contributing to the utilization of chest computed tomographic angiography (CTA).

Study Objectives

To determine what proportion of chest CTAs for suspected pulmonary embolism (PE) were performed in the setting of minimally elevated D-dimer levels, and to determine the prevalence of PE in those patients when stratified by clinical risk.

Methods

Retrospective chart review of all patients who had chest CTA for the evaluation of suspected PE during the years 2002–2006 in a suburban community teaching hospital emergency department.

Results

There were 1136 eligible patient visits, of which 353 (31.1%) were found to have D-dimer levels in the low positive range (0.5–0.99 μg/mL). Of these 353 patients, 9 (2.6%; 95% confidence interval [CI] 0.9–4.2%) were diagnosed with PE. There were also 109 patients (9.6%) who had normal D-dimer levels (<0.5 μg/mL). Two of these 109 (1.8%; 95% CI 0–4.2%) were diagnosed with PE. When stratified by the Pulmonary Embolism Rule-out Criteria, 99 of 353 patients with low positive D-dimer levels (28.0%; 95% CI 23.4–32.7%), and 14 of 109 with normal D-dimer levels (12.8%; 95% CI 6.6–19.1%) were classified as low risk, none of whom had PE.

Conclusions

Nearly one-third of all chest CTAs were done for patients with minimally elevated D-dimer levels, and another 9.6% for patients with normal D-dimer levels with very low yield. Further research to define clinical criteria identifying patients with minimal risk of PE despite low positive D-dimer levels represents an opportunity to improve both patient safety and utilization efficiency of chest CTA.     

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.     

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.     

Risk tolerance for the exclusion of potentially life-threatening diseases in the ED

Objective

Given the same pretest probability (10%) for subarachnoid hemorrhage (SAH), pulmonary embolism (PE), and acute coronary syndrome (ACS), we determined if differences exist in the risk tolerance for disease exclusion according to published guidelines given a negative test result.

Methods

Published guidelines that make practice recommendations on the evaluation of ACS, PE, and SAH were sought using the National Guideline Clearinghouse in low-risk settings. Second-order Monte Carlo simulation was performed to determine point estimates and confidence intervals (CIs) for posttest probabilities assuming a pretest probability of 10%.

Results

Guidelines recommend that patients with low-risk suspected ACS should undergo stress testing. For SAH, computed tomography (CT) followed by lumbar puncture (LP) is recommended without mention of pretest probability; and D-dimer testing is recommended to exclude PE in low-risk patients. Test sensitivity for thallium-201 single photon emission computed tomography (SPECT) was 89%, exercise echocardiogram was 85%, D-dimer testing was 95%, and CT/LP for SAH was 100% (as a gold standard) and CT only was 97.5%. Given a negative test result, for PE, posttest probability was 0.5% (95% CI 0.1%-0.9%); for SPECT, 1.1% (SD 0.5%-1.6%); and for exercise echocardiogram, 1.5% (95% CI 0.5%-2.5%) compared with a posttest probability of 0% for CT followed by LP for SAH. Using a CT-only approach gives a posttest probability of 0.2% (95% CI 0.2%-0.4%).

Conclusions

Guidelines for suspected PE and ACS allow small but nonzero calculated risk end points in low-risk settings, whereas SAH guidelines afford no misses. Because many gold standard tests are more invasive and can have adverse effects, guideline authors should consider adopting a standard acceptable miss rate as an end point for workups with low clinical suspicion to avoid the overuse of invasive testing.     

Impact of altitude-adjusted hypoxia on the Pulmonary Embolism Rule-out Criteria

Background

The Pulmonary Embolism Rule-out Criteria (PERC) defines hypoxia as an oxygen saturation (O2 sat)?<?95%. Utilizing this threshold for hypoxia at a significant elevation above sea level may lead to an inflated number of PERC-positive patients and unnecessary testing. The aim of this study was to determine the effect of an altitude-adjusted O2 sat on PERC's sensitivity and the potential impact on testing rates.

The Pulmonary Embolism Rule-Out Criteria rule in a community hospital ED: a retrospective study of its potential utility

Background

The Pulmonary Embolism Rule-Out Criteria (PERC) rule identifies patients who can be safely discharged from the emergency department (ED) without undergoing laboratory or radiological investigation for possible pulmonary embolism (PE). It was shown to be 99% sensitive in a large validation series. Our objective was to assess the PERC rule's performance in a representative US community hospital.

Methods

A chart review of ED patients receiving computed tomographic scans (CTS) for possible PE during a 4-month study period was performed. The PERC rule was applied to this cohort, and its sensitivity and negative predictive value were determined.

Results

Two hundred thirteen patients underwent chest CTS to “rule out” PE. Forty-eight patients met PERC rule criteria, and all had negative CTS. Of the remaining 165 patients, 18 patients (11%) had scans positive for PE. The overall prevalence of PE was 8.45% (95% CI, 5.22-13.24%). The PERC rule's sensitivity was 100% (95% CI, 78.12-100%), with a negative predictive value of 100% (95% CI, 90.80-100%). Application of the PERC rule at the point-of-care would have reduced CTS by 23%.

Conclusions

In our community hospital, the PERC rule successfully identified ED patients who did not require CTS evaluation for PE. Had the PERC rule been applied, nearly one-quarter of all CTS performed to “rule out PE” could have been avoided.     

Pulmonary embolism in pediatrics

Background

Pulmonary embolism (PE), an uncommon diagnosis in pediatric patients, is a potentially life-threatening condition with significant morbidity and mortality. Improvements in pediatric care have resulted in survival of more chronically and critically ill children and thus, an increased number of pediatric patients at risk for this disease.

Objectives

We review the pathophysiology, risk factors, presentation, diagnosis, and initial management of PE in pediatric patients presenting to the Emergency Department.

Discussion

Although there is a significant lack of pediatric-specific literature pertaining to the diagnosis and management of PE, there are clear differences in the emergency approach to these patients, including specific risk factors and the inutility of clinical decision rules and D-dimer.

Conclusion/Summary

We outline these differences and present rational diagnostic and treatment algorithms.     

Best Clinical Practice: Current Controversies in Pulmonary Embolism Imaging and Treatment of Subsegmental Thromboembolic Disease

Background

Pulmonary embolism (PE) affects >600,000 patients per year in the United States. Evaluation includes clinical decision rules, laboratory tests, and several imaging modalities. The diagnosis of PE has risen in recent years, particularly subsegmental PE (SSPE). Controversy exists concerning the diagnosis and treatment of these lesions.

Radiologic diagnoses of patients who received imaging for venous thromboembolism despite negative D-dimer tests

Objective

The literature supports a negative D-dimer (−DD) excluding venous thromboembolic disease (VTE) in low-risk patients. We determined the radiologic diagnoses in patients where imaging was ordered despite a −DD.

Methods

This is a retrospective chart review of patients with a −DD (Tinaquant; Roche Diagnostics, Mannheim, Germany) and a radiologic study within 48 hours, sought to determine radiologic diagnosis (primary outcome), treatment of VTE, and consensus diagnosis of acute VTE.

Results

Among 3462 DD tests, 1678 met the inclusion criteria. Of 1362 patients with DD values of 350 ng/mL or less, 166 (12.2%) had radiologic studies: 93.4% of the final radiologic diagnoses were negative for VTE, 3.6% were indeterminate, and 3.0% (1.0%-6.9%) were positive; 1.8% ultimately had a consensus diagnosis of acute VTE. In 316 patients with DD values between 351 and 500 ng/mL, 88 (27.8%) had radiologic studies: 95.5% were negative, 1.1% were indeterminate, and 3.4% (0.7%-9.6%) were positive.

Conclusions

Of patients who receive radiologic studies despite −DD tests, 3.0% have positive radiologic diagnoses for acute VTE; only 1.8% had acute VTE after the review of their hospital course.     

Use of the d-dimer for Detecting Pulmonary Embolism in the Emergency Department

Background

Assessment for pulmonary embolism (PE) in the emergency department (ED) remains complex, involving clinical decision tools, blood tests, and imaging.

Risk of venous thromboembolism in patients with borderline quantitative D-dimer levels

Objective

The lower threshold for D-dimer in evaluating patients with low clinical risk of venous thromboembolism (VTE) ranges from 200 to 500 ng/mL. We compared the rates of VTE in patients based on D-dimer values. We hypothesized that the rate of VTE in low-risk patients with D-dimer levels less than 500 would be less than 1%.

Methods

Study Design: This was a retrospective chart review: Setting: The study was performed in a academic, suburban emergency department (ED). Subjects: Emergency department patients with suspected VTE and D-dimer obtained were included in the study. D-dimer assay: The D-dimer assay is a quantitative instrumentation latex suspension of plasma specimens. Outcomes: Presence of VTE within 30 days of ED visit. Data Analysis: Assuming a 0% event rate in patients with D-dimer levels between 200 and 500 ng/mL, a sample of 450 patients would result in a 95% confidence interval upper limit of 0.6%.

Results

There were 1270 ED patients with suspected VTE in which D-dimer levels were performed between October 2005 and October 2006. Patient mean age was 47.8 ± 19.3 years; 63.2% were female, 78.2% were white. Of all D-dimer levels, 497 (39.1%) were less than 200 ng/mL, 479 (37.7%) were between 200 and 500 μg/mL, and 294 (23.1%) were greater than 500 ng/mL. There were no VTE events diagnosed in any of the patients with D-dimer levels less than 200 ng/mL. Four patients with D-dimer levels between 200 and 500 μg/mL had a pulmonary embolism on computed tomography angiography. Of these 4 patients, 3 had moderate clinical risk based on Well's criteria and one had a false-positive computed tomography. There were no cases of VTE in the remaining 475 patients (0%; 95% confidence interval 0%-0.6%).

Conclusion

The rate of confirmed VTE in low-risk patients with D-dimer levels between 200 and 500 ng/mL is very low. Low-risk patients with suspected VTE with D-dimer levels less than 500 ng/mL might not require additional testing.     

Vena caval thromboses

Background

Patients with vena caval (VC) thrombosis have been reported with a variety of clinical presentations, which may create a diagnostic challenge for physicians.

Objective

The objective of the study was to evaluate the clinical characteristics of patients with VC thrombosis.

Patients and Methods

Files and all imaging methods of consecutive patients with superior or inferior VC thrombosis with or without pulmonary embolism (PE) between January 26, 2001, and May 12, 2006, were retrospectively studied in detail.

Results

In our series, VC thromboses within the inferior and superior VC were detected in 28 patients, mostly by combined computed tomographic venography and spiral computed tomographic pulmonary angiography. Nine of these 28 patients (32.1%) had VC thromboses without PE (7 patients with isolated and 2 patients with nonisolated VC thrombosis). Key symptoms and findings in the 9 patients without PE were unexplained dyspnea and tachypnea, respectively.

Conclusions

Many patients with VC thrombosis do not have peripheral vein thrombosis. Moreover, nearly one third of patients with VC thrombosis have negative pulmonary angiograms but do have dyspnea and tachypnea.     

Use of the Triage Stroke Panel in a neurologic emergency service

Background

Acute stroke is associated with serum elevations of numerous markers. We evaluated the additive accuracy of the Triage Stroke Panel (D-dimer, B-natriuretic peptide, matrix metalloproteinase 9, and S-100β) to the triaging nurse for acute stroke diagnosis.

Methods

Consecutive patients with suspected stroke were included in this prospective, controlled, single-center study. A well-trained stroke center triage nurse assigned a probability that the patient had experienced a stroke (certain, very probable, probable, not likely, doubtful, or other); then, the Triage Stroke Panel testing was performed. Patients' diagnosis was based on clinical and imaging data by a neurologist blinded to the test results.

Results

Two hundred four patients were evaluated. Confirmed strokes and transient ischemic attacks (TIAs) were observed in 131 patients. When considering an experienced stroke nurse's assessment of “other,” “doubtful,” or “not likely” to be negative for stroke and categorizing TIA with stroke, the stroke panel's Multimarker Index (MMX) value had identical accuracy (∼70%) and equivalent sensitivity (∼94%) and specificity (∼24%) for stroke diagnosis to that of the nurse. Combining nurse assessment with the MMX result significantly improved the specificity of diagnosing “mimic” vs stroke + TIA from 25.4% (nurse assessment only) to 46.0% (nurse assessment + MMX; P < .001).

Conclusions

The Triage Stroke Panel provides objective information that complements a triage nurse in the assessment of a suspected stroke patient. Its performance compares favorably with that of a well-trained stroke center triage nurse, suggesting potential use in nonexpert centers for improving the accuracy of stroke diagnosis.     

Seizure as a Presentation of Pulmonary Embolism

Background

Seizure is estimated to be the presenting symptom of pulmonary embolism (PE) < 1% of the time. A review of the available literature on the subject indicates that many of the reported cases are postmortem findings, and invariably, are examples of delayed diagnosis and treatment.

Objectives

To heighten physician awareness of the possibility of a PE in patients initially presenting with seizures, and to bring to light some key aspects of the history and physical examination that may assist in the final diagnosis.

Case Report

A 76-year-old man presented to the Emergency Department (ED) after suffering from two tonic-clonic seizures at home. He had a history of one isolated seizure 4 years prior, for which he was not prescribed any medication after full evaluation, including a negative electroencephalogram. In the ED, he was noted to have a resting tachycardia and a room air oxygen saturation of 92%. This prompted further evaluation in the ED. Electrocardiography and D-dimer were ordered, and both were found to be abnormal. Computed tomography scan was positive for multiple large pulmonary emboli. The patient was given an appropriate dose of enoxaparin and admitted to the internal medicine service.

Conclusion

Despite an atypical presentation, the authors were able to diagnose the patient due to a high level of suspicion for the disease. Our goal is to make physicians more attuned to the possibility of a PE as a final diagnosis in patients who present with new-onset seizures.     

Assessment of emergency physician–performed ultrasound in evaluating nonspecific abdominal pain

Study objective

The objective of this pilot study was to lay the groundwork for future studies assessing the impact of emergency physician–performed ultrasound (EPUS) on diagnostic testing and decision making in emergency department (ED) patients with nonspecific abdominal pain (NSAP).

Methods

This was a prospective, noninterventional study using a consecutive sample of patients presenting to the ED with NSAP as determined by nursing triage when a participating physician was available. Nonspecific abdominal pain was defined as abdominal pain for which the patient was seeking evaluation without a presumed diagnosis or referral for specific evaluation. Patients were evaluated by a physician who documented their differential diagnosis and planned diagnostic workup. Then, the physician performed EPUS, recorded their findings, and documented their post-EPUS differential diagnosis and planned diagnostic workup. This was compared with the patient's final diagnosis as determined by 2 emergency physicians blinded to the EPUS results.

Results

A total of 128 patients were enrolled. Fifty-eight (45%; 95% confidence interval [CI], 36%-54%) had an improvement in diagnostic accuracy and planned diagnostic workup using EPUS. Sixty-four (50%; 95% CI, 41%-59%) would have been treated without further radiographic imaging. Fifty (39%; 95% CI, 31%-48%) would have been treated without any further laboratory testing or imaging.

Discussion

Based on our findings, a future trial of 164 consecutive patients would have 90% power to confirm a 25% reduction in testing and a 25% improvement in decision making.

Conclusion

Emergency physician–performed ultrasound appears to positively impact decision making and diagnostic workup for patients presenting to the ED with NSAP and should be studied further.     

Value of ischemia-modified albumin in the diagnosis of pulmonary embolism

Background

Pulmonary embolism (PE) is a common condition, but the diagnostic strategy for the evaluation of suspected PE is somewhat controversial. Despite the use of various biochemical markers (such as D-dimer and C-reactive protein) and various probability calculation algorithms based on clinical findings for that purpose, there is still a need for more specific and practical markers in PE diagnosis. The aim of this study was to investigate the diagnostic value of ischemia-modified albumin (IMA) levels in the diagnosis of PE.

Methods

This case-control study was performed in the emergency department between March and September 2006. The serum IMA levels of a total of 60 individuals, consisting of 30 PE patients who had been definitively diagnosed via spiral computed tomographic angiography and 30 healthy volunteers, were examined.

Results

The measurement of IMA levels in patient plasma yielded mean values of 0.724 ± 0.122 absorbance unit (ABSU) in the PE group and 0.360 ± 0.090 ABSU in the control group. When plasma IMA levels in the PE group were compared with those in the control group, statistically significant increases in IMA were observed in the former (t = 13.19, df = 56, P < .0005). The value of 0.540 ABSU was calculated as the upper limit of reference interval. In the PE group, 97.7% (n = 29) had values exceeding 0.540 ABSU; none of the control subjects had values exceeding this cutoff value.

Conclusions

In conclusion, our data suggest that IMA levels may be useful as a discriminative marker to exclude pulmonary embolism.     

Prospective comparison of emergency physician–performed venous ultrasound and CT venography for deep venous thrombosis

Background

Venous thromboembolic disease is a major cause of mortality and morbidity.

Objectives

The aim of this study is to compare emergency physician–performed ultrasound (EPPU) of the lower extremities with CT venography (CTV) in emergency department (ED) patients undergoing workup for pulmonary embolism (PE).

Methods

This was a prospective study performed at a busy academic ED. Adult patients (>18) undergoing workup for PE were eligible for the study; enrollment was based on a convenience sample, during hours worked by the investigators. Study patients underwent EPPU of the lower extremities followed by CT angiogram (CTA) of the chest and CTV of the lower extremities. Sensitivity and specificity of the ultrasound examination were calculated using CTV as the gold standard.

Results

A total of 61 patients were enrolled. Of 61 patients, 50 (82%; 95% confidence interval [CI], 72%-91%) had negative workups; 11 (18%; 95% CI, 8%-27%) were noted to have PE on CTA; 6 (10%; 95% CI, 2%-17%) were noted to have lower extremity deep venous thrombosis (DVT) on both EPPU and CTV evaluation; whereas 1 patient was found to have an external iliac DVT on CTV, which was not noted on EPPU. All patients with DVT (by either EPPU or CTV) were found to have PE on CTA. Sensitivity and specificity of EPPU when compared to CTV in the diagnosis of DVT was 86% (95% CI, 42%-99%) and 100% (95% CI, 91%-100%), respectively.

Conclusions

Emergency physician–performed ultrasound produces results consistent with CTV in the diagnosis of femoropopliteal DVT. More proximal clots are not evaluated with EPPU and thus may result in a false negative.     

Family history of venous thromboembolism predicts the diagnosis of acute pulmonary embolism in the emergency department

Background

Pulmonary embolism (PE) clinical decision rules do not consider a patient's family history of venous thromboembolism (VTE). We evaluated whether a family history of VTE predicts acute PE in the emergency department (ED).