a b s t r a c t

Objectives: To determine the ability of emergency physicians to detect complex abnormalities on point-of- care (POC) echocardiograms.

Methods: Single-blinded, nonrandomized, cross-sectional study. Twenty-five different emergency medicine clinical scenarios (video clips and digital images) covering a variety of echocardiographic abnormalities were presented to a group of emergency physician sonologists. The echocardiographic abnormalities included right ventricular dysfunction, left ventricular systolic dysfunction, diastolic dysfunction, regional wall motion abnormalities, Doppler abnormalities of Pericardial tamponade physiology, left ventricular hypertrophy, Hypertrophic cardiomyopathy, and aortic abnormalities. All emergency physician sonologists were blinded to the study hypothesis. They reviewed echocardiography video clips and images individually, and their interpretations were compared with the criterion standard (expert echocardiog- rapher interpretations).

Results: A total of 200 echocardiography studies (video clips and images) were independently reviewed by 8 emergency physician sonologists with varying POC echocardiography experiences. Emergency physicians accurately identified left ventricular systolic dysfunction 94% of the time, diastolic dysfunction (100%), and right ventricular dysfunction 80% of the time. regional wall motion abnormalities were detected only 50% of the time. Doppler echocardiographic abnormalities of pericardial tamponade physiology were accurately identified 57% of the time. Emergency physicians who performed more than 250 POC echocardiograms were found to be more accurate in identifying complex echocardiographic abnormalities.

Conclusions: Our study results suggest that with increased experience, emergency physicians can accurately identify most of complex echocardiographic abnormalities.

(C) 2014

Introduction

The use of point-of-care (POC) ultrasound has greatly expanded in the past 2 decades. Emergency physicians are increasingly using bedside ultrasound for a variety of applications [1]. The accuracy, repeatability, portability, and noninvasive characteristics of ultra- sound make it an ideal device for use at bedside in the emergency department (ED). Prior studies have demonstrated the ability of emergency physicians to accurately perform focused bedside echo- cardiograms [2-5]. Focused Bedside echocardiography has become a valuable tool in the diagnosis of pericardial effusion, pulmonary embolism, assessment of volume status, estimation of left ventricular

? Funding sources: None.

?? Disclosures: None.

* Corresponding author. Department of Emergency Medicine, University of Arizona Medical Center, Tucson, AZ 85724. Tel.: +1 520 626 9604; fax: +1 520 626 2480.

E-mail address: [email protected] (S. Adhikari).

function, management of shock and cardiac arrest [3-11]. point-of-care echocardiography has been shown to accurately narrow the differen- tial diagnosis of nontraumatic undifferentiated hypotension and alter the management of critically ill ED patients [8]. Bedside echocardiog- raphy can assist with rapid diagnosis and administration of thrombo- lytics in patients with suspected pulmonary embolism [12]. When compared with other imaging modalities such as computed tomo- graphic angiogram, bedside echocardiography was found to be very specific for detecting proximal aorta abnormalities [13].

In recent years, there is growing interest among emergency

physicians to learn advanced echocardiography. Advanced echocardi- ography is listed as one of the emerging emergency ultrasound applications in the most recent American College of Emergency Physicians Emergency Ultrasound Guidelines [1]. In the Council of Emergency Medicine Residency Directors-Academy of Emergency Ultrasound emergency ultrasound milestones consensus document, estimation of global left ventricular function and global right ventricular size and assessment for tamponade physiology were listed

0735-6757/$ – see front matter (C) 2014 http://dx.doi.org/10.1016/j.ajem.2013.12.010

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under core skills. Estimation of chamber size, cardiac output, regional wall motion, aortic root and valvular assessment were listed under advanced skills [14]. To our knowledge, no prior study has shown that emergency physicians can accurately identify complex abnormalities on echocardiograms. The objective of this study was to determine the ability of emergency physicians to detect complex abnormalities on POC echocardiograms.

Methods

Study design and setting

This was a single-blinded, nonrandomized, cross-sectional study at an academic medical center with an emergency medicine residency training program and an active emergency ultrasound education program. Hospital credentialing in POC ultrasound was available for emergency physicians and was based on American College of Emergency Physicians ultrasound guidelines [1]. The study was approved by the institutional review board.

Selection of participants

Emergency medicine faculty with expertise in POC ultrasound were invited to participate in this study, and participation was voluntary. The emergency physician sonologists who contributed to this study were credentialed to use bedside ultrasound in ED by the hospital. All participants had experience in performing common ED POC ultrasound applications. They were either fellowship trained in emergency ultrasound or had significant experience in performing and teaching emergency ultrasound. All participants had attended at least 20 hours of didactic sessions in POC echocardiography and performed 75 proctored POC echocardiograms covering advanced echocardiography techniques (B-mode, M-mode, and Doppler). Specific information regarding prior scanning experience with bedside echocardiography was collected.

Study protocol

Twenty-five different emergency medicine clinical scenarios cover- ing a variety of echocardiographic abnormalities were presented to emergency physician sonologists. Video clips and digital images were included in clinical scenarios. The images were obtained using Z.one ultra system (Zonare Medical Systems, Mountain View, CA) with a phased-array (P 4-1c) transducer. Echocardiographic abnormalities (Table) included right ventricular dysfunction, left ventricular systolic

Table

Echocardiographic abnormalities included in the clinical scenarios

Right ventricular dysfunction

right ventricular dilatation and hypokinesis Paradoxical septal motion

Abnormal tricuspid annular plane systolic excursion McConnell sign

Left ventricular systolic dysfunction Mitral annular plane systolic excursion E point septal separation

Fractional shortening Diastolic dysfunction

Mitral inflow patterns (E/A, deceleration time, isovolumic relaxation time) Mitral annulus velocities by Tissue Doppler (E/e? ratio)

Regional wall motion abnormalities Anterior, inferior, septal, and lateral Pericardial tamponade

Exaggerated Respiratory variation in transmitral Doppler inflow velocities Left ventricular hypertrophy (B-mode and M-mode)

Hypertrophic cardiomyopathy Asymmetrical septal hypertrophy

Systolic anterior motion of the mitral valve Aortic dissection (Suprasternal view)

dysfunction, diastolic dysfunction, and regional wall motion abnormal- ities. Doppler abnormalities included pericardial tamponade physiolo- gy, left ventricular hypertrophy, hypertrophic cardiomyopathy, and aortic abnormalities. Some of these abnormalities were very subtle and can be easily overlooked. Video clips consisted of B-mode, M-mode, and Doppler echocardiographic methods of measurement. Besides tradi- tional cardiac views (subxiphoid, parasternal, and apical), suprasternal echocardiography images were incorporated. Video clips demonstrated a combination of Qualitative and quantitative methods for estimation of left ventricular function. Clinical scenarios also consisted of normal echocardiographic clips with no abnormalities.

All emergency physician sonologists were blinded to the study

hypothesis. They were informed that this was a quality assurance exercise. They reviewed echocardiography video clips and images individually. They were asked to interpret and determine if there were any abnormalities. The participants were provided a list of echocar- diography findings (mixture of normal and abnormal) and were asked to choose their answers (interpretations) from the list. Their responses were recorded and compared with the criterion standard (expert echocardiographer interpretations). If their interpretations did not agree with expert echocardiographer interpretations, the responses were deemed inaccurate. Each response in a clinical scenario was counted separately during data analysis.

Statistical analysis

All analyses were performed in SAS version 9.3. (Copyright, SAS Institute Inc, Cary, NC). Data were analyzed using descriptive statistics. Continuous data are presented as means with 95% confidence intervals.

Results

A total of 200 echocardiography studies (video clips and images) were independently reviewed by 8 emergency physician sonologists. Emergency physician sonologists had varying POC echocardiography scanning experiences. Three had performed 100 to 150 POC echocardiograms, 3 had performed 250 to 300 POC echocardiograms, and 2 had performed more than 500 POC echocardiograms. All participants had used advanced echocardiography techniques (B- mode, M-mode, and Doppler) in the past. None of the participants reported any problems with ultrasound Image quality. Emergency physicians accurately identified left ventricular systolic dysfunction 94% of the time, diastolic dysfunction (100%), and right ventricular dysfunction 80% of the time. Regional wall motion abnormalities were detected by emergency physicians only 50% of the time. Doppler echocardiographic abnormalities of pericardial tamponade physiolo- gy were accurately identified 57% of the time. Aortic abnormalities (suprasternal view) were recognized by the participants 37% of the time. Left ventricular hypertrophy was accurately diagnosed only 25% of the time. Emergency physicians who performed more than 250 POC echocardiograms were found to be more accurate in identifying complex echocardiographic abnormalities.

Discussion

Point-of-care echocardiography has become a diagnostic tool that is commonly used in the ED for evaluation of acutely ill patients. Most recent studies suggest that there is growing interest among emergency physicians to learn advanced echocardiographic tech- niques [4,5]. Emergency physicians frequently evaluate and manage patients with serious or life-threatening conditions. Ability to interpret subtle echocardiographic abnormalities and familiarity with complex echocardiographic methods of measurement can help make early accurate diagnosis. This can, in turn, significantly impact patient outcomes including morbidity and mortality.

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Early diagnosis of acute myocardial ischemia can avoid delays in definitive treatment and prevent adverse outcomes. It has been shown that regional wall motion abnormalities appear within seconds after the onset of severe ischemia from acute coronary occlusion, which can be visualized echocardiographically [15]. To our knowl- edge, no prior studies investigated the ability of emergency physicians to detect regional wall motion abnormalities. Several cases of acute coronary syndrome with wall motion abnormalities were reviewed by emergency physicians in this study. Some of these wall motion abnormalities were very subtle. Our study participants accurately detected regional wall motion abnormalities only 50% of the time. Our findings are not surprising, given that prior studies have shown that there was disagreement among experienced cardiologists in identi- fying wall motion abnormalities [16]. Accuracy of the assessment of wall motion is generally dependent on image quality, plane of imaging, and experience of the echocardiographer [17]. Future studies that directly compare the accuracy of emergency physicians with that of cardiologists, in identifying wall motion abnormalities, are needed. Point-of-care echocardiography is highly sensitive in detecting pericardial effusions in Symptomatic ED patients [6]. Recognizing echocardiographic signs of pericardial tamponade physiology prior to Hemodynamic compromise can expedite the treatment and prevent adverse outcomes in these patients. The ability of emergency physicians in detecting Doppler echocardiographic abnormalities of pericardial tamponade has not been reported in the literature. The case scenarios in our study included video clips and images demonstrating respiratory variations of transmitral and transtricuspid Doppler inflow velocities (Fig.). Doppler abnormalities suggesting pericardial tamponade physiology were accurately detected 57% of the time by emergency physicians in this study. Interpretation of abnormalities in transvalvular flow velocities requires considerable additional skill, which is generally acquired with increasing echocar-

diography experience.

Rapid determination of left ventricular function using POC echocardiography can have a significant impact on the diagnosis and management of hemodynamic disorders in ED. Prior studies have shown that emergency physicians can accurately determine left ventricular function in hypotensive ED patients [2,3]. Dinh et al [4] demonstrated that emergency physicians can measure cardiac index by obtaining left ventricular outflow tract diameter and velocity time integral measurements. In our study, we used video clips that demonstrated a combination of qualitative and quantitative tech- niques (2D and M-mode) including mitral annular plane systolic

Fig. Doppler transmitral flow pattern in pericardial tamponade. Note the change in E- wave amplitude with respiration (N25% variation in peak E-wave velocities).

excursion, fractional shortening, and E point septal separation to estimate left ventricular systolic function. Regardless of their scanning experience, emergency physicians accurately identified left ventric- ular systolic dysfunction majority (94%) of the time. Besides systolic dysfunction, we also investigated the accuracy in diagnosing diastolic dysfunction. The indices used in this study to estimate Diastolic function include mitral inflow patterns (E/A, deceleration time, isovolumic relaxation time), and mitral annulus velocities by tissue Doppler (E/e? ratio). Diastolic dysfunction was identified by emer- gency physicians in our study 100% of the time. Our results were similar to those of a prior study performed by Unluer et al [5], which showed that emergency physicians are accurate in diagnosing diastolic dysfunction.

Pulmonary embolism is an elusive diagnosis and presents considerable diagnostic challenges to emergency physician. Delays in diagnosis are associated with significant morbidity and mortality. Emergency physician-performed bedside echocardiography for right ventricular strain was found to be a significant predictor of in-hospital adverse outcomes in ED patients diagnosed as having pulmonary embolism [10]. The use of POC echocardiography in rapid diagnosis and administration of thrombolytics in patients with suspected pulmonary embolism has been reported in the literature [12]. Video clips demonstrating echocardiographic methods of right ventricular function measurement (dimensions of chambers, abnormal tricuspid annular plane systolic excursion) were accurately interpreted more than three-fourths of the time by our study participants. Some of the abnormalities that suggested right ventricular dysfunction, specifi- cally the McConnell sign, were very subtle. Such subtlety could have contributed to misinterpretation.

To achieve competency, American College of Emergency Physi- cians guidelines recommend 25 to 50 cases per each application after didactic training [1]. In the study done by Moore et al [2], emergency physicians who completed 100 noncardiac ultrasound examinations accurately determined left ventricular function in hypotensive adult patients after focused training in echocardiography (didactics, specific echocardiography training, and pilot study/review). Similar results were reported by Randazzo et al [3], where emergency sonographers who performed 150 noncardiac ultrasound examina- tions were able to accurately estimate left ventricular function with a small amount of focused additional training. In our study, emergency physicians who performed more than 250 POC echocardiograms were very accurate in detecting complex echocardiographic abnormalities. The echocardiographic techniques and abnormalities included in our study are far more advanced and complex compared with prior studies. Our results suggest that additional echocardiography scan- ning experience beyond basic level is required to detect subtle abnormalities. More experienced physician sonologists can accurately detect complex echocardiographic abnormalities with confidence. Specific scanning experience with advanced echocardiographic methods of measurement is helpful while interpreting echocardio- grams with complex abnormalities. The scope of POC echocardiog- raphy in the ED is rapidly expanding. Future research may expand on the impact of advanced echocardiographic experience of emergency physicians on patient outcomes.

This study has a number of limitations including a small sample

size, which may limit the conclusions that could be reached. convenience sampling of emergency physicians might have intro- duced a selection bias. The emergency physicians who contributed to this study may have more advanced echocardiography experience compared with an average emergency physician sonologist, which limits the generalizability of these study findings. In addition, doing this study at an institution with emergency physicians who are interested in participating in the study might have introduced a bias. It is difficult to estimate what the results of a study would have been if focused on physicians not motivated in participating in the study. The methods used in this study to determine the ability of emergency

366 S. Adhikari et al. / American Journal of Emergency Medicine 32 (2014) 363–366

physicians to identify complex echocardiographic abnormalities were not validated. To our knowledge, no standardized Ultrasound measurement tools are available to assess the accuracy of interpre- tation, and we believe that the methods adopted in this study are reliable to measure the accuracy. The video clips included in our study did not cover all sonographic abnormalities of hemodynamic disorders seen in ED. In addition, image acquisition skills of our participants were not assessed.

Conclusions

Our study results suggest that with increased experience, emergency physicians can accurately identify most of complex echocardiographic abnormalities.

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