Imaging/original research
Right Ventricular Dilatation on Bedside Echocardiography Performed by Emergency Physicians Aids in the Diagnosis of Pulmonary Embolism

Presented as a poster at the American College of Emergency Physicians Scientific Assembly, October 2011, San Francisco, CA.
https://doi.org/10.1016/j.annemergmed.2013.08.016Get rights and content

Study objective

The objective of this study was to determine the diagnostic performance of right ventricular dilatation identified by emergency physicians on bedside echocardiography in patients with a suspected or confirmed pulmonary embolism. The secondary objective included an exploratory analysis of the predictive value of a subgroup of findings associated with advanced right ventricular dysfunction (right ventricular hypokinesis, paradoxical septal motion, McConnell's sign).

Methods

This was a prospective observational study using a convenience sample of patients with suspected (moderate to high pretest probability) or confirmed pulmonary embolism. Participants had bedside echocardiography evaluating for right ventricular dilatation (defined as right ventricular to left ventricular ratio greater than 1:1) and right ventricular dysfunction (right ventricular hypokinesis, paradoxical septal motion, or McConnell's sign). The patient's medical records were reviewed for the final reading on all imaging, disposition, hospital length of stay, 30-day inhospital mortality, and discharge diagnosis.

Results

Thirty of 146 patients had a pulmonary embolism. Right ventricular dilatation on echocardiography had a sensitivity of 50% (95% confidence interval [CI] 32% to 68%), a specificity of 98% (95% CI 95% to 100%), a positive predictive value of 88% (95% CI 66% to 100%), and a negative predictive value of 88% (95% CI 83% to 94%). Positive and negative likelihood ratios were determined to be 29 (95% CI 6.1% to 64%) and 0.51 (95% CI 0.4% to 0.7%), respectively. Ten of 11 patients with right ventricular hypokinesis had a pulmonary embolism. All 6 patients with McConnell's sign and all 8 patients with paradoxical septal motion had a diagnosis of pulmonary embolism. There was a 96% observed agreement between coinvestigators and principal investigator interpretation of images obtained and recorded.

Conclusion

Right ventricular dilatation and right ventricular dysfunction identified on emergency physician performed echocardiography were found to be highly specific for pulmonary embolism but had poor sensitivity. Bedside echocardiography is a useful tool that can be incorporated into the algorithm of patients with a moderate to high pretest probability of pulmonary embolism.

Introduction

Pulmonary embolism is a common and highly lethal entity that is often misdiagnosed.1 Despite an increased awareness of pulmonary embolism and improved diagnostic testing, there are still a significant number of fatal pulmonary embolisms not diagnosed until autopsy.1, 2, 3, 4 An estimated 1.35 million Americans have a pulmonary embolism every year.5 Short-term mortality estimates vary widely, from 2.5% to as high as 33%.6, 7, 8 Twenty-five thousand pulmonary embolism–related deaths are recorded annually in the United States,9 but this is likely an underestimation of the true mortality because of the ones not discovered until autopsy.

Pulmonary embolism causes morbidity and mortality through right ventricular outflow obstruction, which may lead to increased pulmonary artery pressure, right ventricular failure, left ventricle failure, and circulatory collapse. Right ventricular dysfunction has been found on echocardiography in 27% to 40% of normotensive patients with a pulmonary embolism and can predict hemodynamic instability and circulatory collapse.8, 10, 11 Evidence of right ventricular dysfunction on echocardiography includes dilatation of the right ventricle (Figure 1), right ventricular hypokinesis, paradoxical septal motion (flattening or bowing of the interventricular septum toward the left ventricle), McConnell's sign (right ventricular free wall hypokinesis with apical sparing), and tricuspid regurgitation.12, 13, 14, 15, 16

Editor's Capsule Summary

What is already known on this topic

Right ventricular dysfunction on echocardiography is associated with a worse prognosis in pulmonary embolism. Prompt treatment of pulmonary embolism appears to be associated with better outcomes.

What question this study addressed

Can emergency department bedside echocardiography in patients with suspected pulmonary embolism reliably identify those who have right ventricular dysfunction, potentially leading to earlier diagnosis and treatment?

What this study adds to our knowledge

This observational study of a convenience sample of 146 patients with moderate to high risk or confirmed pulmonary embolism found that right ventricular dysfunction was highly specific for pulmonary embolism.

How this is relevant to clinical practice

Bedside echocardiography may be a useful addition to diagnostic protocols for suspected pulmonary embolism, but how much it adds to other clinical findings remains to be determined.

Two thirds of patients who die from a pulmonary embolism do so within the first hour of presentation, and 75% of deaths occur during the initial hospitalization.8, 17 Prompt treatment has been associated with lower mortality rates.6, 18, 19 Diagnosis of pulmonary embolism can be delayed by a number of problems, including difficulty obtaining intravenous access, renal impairment resulting in the inability to administer intravenous contrast, wait times for imaging, and the inability to obtain some imaging at certain times of day. These delays can impede the initiation of treatment and may lead to increased mortality.6, 18

The utility of point-of-care ultrasound in the emergency department (ED) is well established. It includes the use of bedside echocardiography by emergency physicians to diagnose pericardial effusion, right ventricular strain, cardiac function, and volume status.20 The presence of right ventricular dilatation on echocardiography in patients with a pulmonary embolism has been shown to be associated with permanent right ventricular dysfunction, right ventricular failure, recurrent pulmonary embolism, and death.11, 21, 22 If a dilated right ventricle is identified on bedside echocardiography in patients with a suspicion of pulmonary embolism, decisions about treatment and disposition could be expedited, resulting in a possible reduction in morbidity and mortality.

The primary objective of this study was to determine the diagnostic performance of right ventricular dilatation as identified by emergency physicians on bedside echocardiography in patients with suspected or confirmed diagnosis of pulmonary embolism. The secondary objective included an exploratory analysis of the predictive value of a subgroup of sonographic findings associated with advanced right ventricular dysfunction on bedside echocardiography, including signs of right ventricular hypokinesis, paradoxical septal motion, and McConnell's sign.

Section snippets

Study Design and Setting

We performed a prospective observational study, using a convenience sample of ED patients with suspected or confirmed pulmonary embolism, from June 2009 to August 2011. The study was performed in the ED at Boston Medical Center, a large urban academic medical center with greater than 130,000 annual visits. The ED is staffed by board-certified emergency physicians and emergency medicine residents. The institutional review board at the Boston University School of Medicine approved this study.

Four

Results

Between June 2009 and August 2011, 272 patients with a moderate to high pretest probability of pulmonary embolism were identified during study hours and either had imaging ordered in the ED or were diagnosed with a pulmonary embolism prior to arrival (Figure 2). Fifty-three patients were excluded from the study (41 were non-English speaking, 1 was a prisoner, and 11 were unable to be approached for informed consent for reasons that did not meet waiver of consent criteria). Of the 11 patients

Limitations

This was a single-site study performed at an academic ED with emergency medicine residents and an active ultrasound section. The physician-investigators all completed special training requirements in cardiac sonography to be part of this study. These results may not be easily reproduced by other emergency physicians who do not have ultrasound requirements in residency, are further removed from their ultrasound training, or who did not specifically receive training in cardiac sonography. The

Discussion

In this study, we found that right ventricular dilatation on bedside echocardiography was highly specific for pulmonary embolism (98%) but had poor sensitivity (50%). Our study showed very high specificity compared with that found in previous literature. It is likely that the younger age (mean of 49 years) of our patient population enrolled eliminated many patients with chronic obstructive pulmonary disease who can have signs of chronic right ventricular dysfunction on echocardiography. The

References (35)

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Supervising editor: Allan B. Wolfson, MD

Author contributions: PM and KC conceived the study, designed the trial, and supervised the conduct of the trial and data collection. SD, ML, AS, and KC collected the data, including performing the echocardiography. LR and JR-S undertook recruitment of patients and managed the data, including quality control. SB, BL, and LW provided statistical advice on study design and analyzed the data. SD and KC drafted the article, and all authors contributed substantially to its revision. KC takes responsibility for the paper as a whole.

Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist.

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