The Pocus Report | Winter 2022

Welcome from EUS-AAEM

The Emergency Ultrasound Section of the American Academy of Emergency Medicine (EUS-AAEM) was founded to foster the professional development of its members and to educate them regarding point-of-care ultrasound. This group will serve as a venue for collaboration among medical students, residents and practitioners who are interested in point-of-care ultrasound. The purpose of our group is to augment the knowledge and expertise of all emergency medicine specialists and to advocate for patient safety and quality care by endorsing bedside ultrasound. Membership is not limited to fellowship trained physicians. All emergency medicine practitioners passionate about ultrasound are welcome to join and participate.

We are proud to publish our e-newsletter with original contributions from many of our members. We encourage all members to submit for future editions. Topics include but are not limited to educational, community focus, interesting cases, resident and student section, and adventures abroad.

For more information, visit us at: www.aaem.org/eus

In this Issue

President’s Message

Opportunities to Get Involved

Wanted: Speakers

Opportunity for EMIGs

Ultrasound Building Blocks

Importance of Using Proper Settings in Focused Echocardiography

Glimpse of Original Research

Diagnostic Ultrasound Measurement of Acromioclavicular Joint Position Under Varying Upper Extremity Positions and Loads

Accuracy of Emergency Medicine Resident Performed Point-of-Care Ultrasound

Section

Ultrasound Has Got Your Back: Posterior Shoulder Dislocations

For Femoral Artery Pseudoaneurysm

Ultrasound Guided Procedures

An Introduction to Ultrasound Guided Nerve Blocks in the Emergency Department

Saves

Clot-in-Transit During Cardiac Arrest

President’s Message

Hello EUS-AAEM Members,

It’s hard to believe that it’s already time for the Winter issue of the POCUS Report. The year is flying by for the Emergency Ultrasound Section as we continue to evolve our offerings to best serve our membership and advance Point of Care Ultrasound education to our community

One of my goals for the year has been to increase value to our membership. One way we are doing that is through the 1st Annual Emergency Ultrasound Photo Competition. We look forward to seeing all the posters in New Orleans for AAEM23!

A true highlight of membership remains the Unmute Your Probe webinars, available to EUS members free of charge. Access to recordings of all previous webinars is also included.

The Section remains passionate about our mission to bring ultrasound education to emergency medicine practitioners regardless of practice setting and experience. We have made significant strides to bring this education directly to colleagues through the Regional Hands-On Ultrasound Course. Designed with busy practicing emergency physicians in mind, this course brings a customizable curriculum and skilled educators directly to learners.

With an eye to the future leaders of emergency medicine and point of care ultrasound, the Speakers Bureau is underway. By connecting medical student groups to ultrasound enthusiasts, we can provide the next generation of physicians with supplemental ultrasound education geared to their particular interests and needs, while providing opportunity for academic development for lecturers.

EUS looks forward to offering additional ultrasound education and networking at the 29th Annual Scientific Assembly in New Orleans. If you have any questions or are looking for ways to get involved, please don’t hesitate to email me at alli.zanaboni@gmail.com.

Allison Zanaboni, MD FAAEM EUS-AAEM Chair, 2022-2023

Opportunities to Get Involved

Help Wanted: Speakers

The Emergency Ultrasound Section is looking for interested residents, fellows and faculty to speak with medical school Emergency Medicine Interest Groups and Ultrasound Interest Groups about the use of point of care ultrasound in the Emergency Department.

The section will provide a list of suggested topics to the Interest Groups, as well as providing you with several slide sets to use if you choose as a basis for lectures. This is a great opportunity for anyone interested in sparking interest in the next generation of Emergency Physicians in the use of point of care ultrasound in the Emergency Department! Interested physicians may sign up here

An Opportunity for EMIGs

The American Academy of Emergency Medicine Emergency Ultrasound Section has an exciting new opportunity focused on providing emergency ultrasound education to groups like yours. The section has compiled a group of point of care ultrasound enthusiasts who are making themselves available to give virtual talks on a variety of emergency ultrasound topics. This is a great chance to get directed education on an exciting and ever expanding diagnostic topic directed to your group's specific interest. If you think your group would be interested in taking advantage of this opportunity, please sign up through the sign-up link below.

Please designate your interest on this worksheet.

Ultrasound Building Blocks

Importance of Using Proper Settings in Focused Echocardiography

Yash Chavda, DO and Steve Choi, DO

Case:

A 64-year-old male was brought to the Emergency Department (ED) by EMS for a motor vehicle collision. He was driving on a highway when he hit a fence at moderate to high speed and drove off into a wooded area where his car stopped spontaneously. His only medical history was hypertension. Upon arrival to the ED the patient was speaking, bilateral lung sounds were present. He was mentating well and overall perfusion appeared normal but the nurses were having a difficult time obtaining a blood pressure on either extremity. He was diaphoretic. Upon exposure the patient had no external signs of trauma. A FAST examination was negative for free fluid, but while evaluating for pericardial effusion the aortic outflow tract appeared strange (Figure 1). The ultrasound setting was switched to cardiac mode where clearer visualization of the aorta demonstrated findings concerning for a flap with a dilated aortic root (Figure 2).

Figure 1 : rP19x/5-1 Parasternal Long axis view with phased array probe in abdominal setting - note lack of dynamic range and overall poorer quality image. While the aortic root does look dilated, it is not entirely clear.

Figure 2 : rP19x/5-1 Parasternal long axis view phased array probe with cardiac setting - note the higher dynamic range and sharper image brought by tissue harmonic imaging, leading to visualization of the tissue flap and better aortic root visualization.

After not being able to obtain an upper extremity blood pressure on the patient, the trauma team placed a right femoral arterial line and right femoral introducer sheath for possible transfusion or other interventions. The arterial line blood pressures read 180/100. The patient was rushed to the CT scanner where an acute type A aortic dissection was visualized (Figure 3). The dissection extended into the left subclavian, left vertebral, left common carotid, right brachiocephalic, right subclavian, and right common carotid arteries. It extended down to the level of the renal arteries.

Figure 3 : CTA showing Type A aortic dissection in sagittal view.

The patient was given labetalol bolus, started on a labetalol and nicardipine infusion and was accepted for helicopter transfer to the nearest cardiothoracic surgery capable facility. As soon as the patient was moved from the hospital stretcher to the helicopter stretcher the patient had a tonic clonic seizure thought to be due to cerebral hypoperfusion. The decision was made to intubate the patient for safe transfer. The patient was successfully received by the accepting hospital and had a successful total aortic surgery.

Discussion

Aortic dissection (AD), characterized by an intimal tear in the aortic wall, is a medical emergency with high mortality and morbidity [2] . The most common classification system is the Stanford that separates AD into Type A, which involves the ascending aorta and requires emergent surgical repair, and Type B that does involve the ascending aorta and is treated initially with medical therapy [2] . AD has variable clinical presentations making the diagnosis difficult. Patients often present with chest, back, or abdominal pain. It can present as sudden onset, tearing pain, with pulse or blood pressure differences between extremities but this presentation is only seen in <50% of patients [5]. Early methods of diagnosis in the ED are crucial for rapid intervention. The current gold standard for diagnosis of acute aortic dissection is CTA, MRA, or TEE with CTA often being used in ED. However, these modalities are limited by length of time, injection of contrast material, and transportation of patients when time is of essence for these patients [2] .

Bedside point-of-care ultrasound (POCUS) echocardiography is often the initial study of choice in the ED for acute aortic dissection as it is readily available for assessment of critically ill patients with acute chest pain where differential diagnoses are broad [2, 3] . It is also a valuable tool in identifying complications from AD including acute aortic valve insufficiency, cardiac tamponade, acute myocardial ischemia, or aortic rupture or exsanguination. The American Society of Echocardiography states evaluation of aortic root is best done in the parasternal long-axis view [6]. Even then, the use of multiple windows significantly improves the detection of an AD [11]. Gibbon et al. developed AD-POCUS protocol combining TTE and abdominal aorta US. Evaluation of transthoracic and transabdominal US for AD shows aortic root dilatation sensitivity of 77% and specificity of 95% and presence of intimal flap has sensitivity of 67% to 80% and specificity of 99% to 100% [3]. POCUS signs of Type A Stanford AD are dilated aortic root at end-diastole >3.5cm, intimal flap, intramural thrombus, pericardial effusions, aortic regurgitation, and “Mercedes Benz” sign in subxiphoid view [1] .

Ultimately, emergency medicine physicians should know that there are significant differences between ultrasound settings that may affect their visualization of these signs. Best possible image parameter settings should be achieved including adequate depth penetration, image width, spatial and temporal resolution, image contrast, artifact suppression, and zoom application [10] . There are inherent differences in abdominal and cardiac settings that influence image quality of different organ parenchyma:

Dynamic Range

Dynamic Range is defined as echo strengths and the total number of gray scales displayed on a US monitor, and can be characterized as low or high. High dynamic range gives more information on echo

patterns and appears brighter and softer, better representing organ parenchyma like cardiac images. Low dynamic range allows higher contrasts of black and white images with coarse echo pattern which is ideal when visualizing abdominal organs [10] . This difference can be visualized by comparing figure 1 (low dynamic range) and figure 2 (high dynamic range). Note the visualization of tissue flap and better aortic root visualization with cardiac setting which are absent in abdominal setting. Cardiac grayscale maps optimize blood-tissue border and distinguish subtle differences from weak reflectors like myocardium [7] .

Frame Rate

The frame rate is significantly higher in cardiac setting than in abdominal setting. A low framerate would produce very blurred images if used with sector transducers in echocardiography [10] . A high frame rate is essential to observe the rapid motion of myocardium and valves [4] .

Tissue harmonic imaging (THI)

THI is another difference between cardiac setting and abdominal settings. THI utilizes the second harmonic to minimize artifactual echoes. It leads to a significantly increased number of readable studies and better grayscale [8]. When ultrasound waves pass through the body, tissues resonates, creating harmonic frequencies, which are usually multiples of the frequency sent to the tissue. The ultrasound machine use the 2nd harmonic frequency to create images that usually contain more information, at the potential cost of axial resolution[8]

Conclusion

This case emphasizes the importance of understanding differences in ultrasound instrumentation settings as image qualities are influenced by specific organ parenchyma and image acquisition. Understanding the differences between abdominal settings and cardiac settings is essential for emergency medicine physicians to obtain the best imaging possible. The cardiac setting should be used to discern subtle pathologies in focused echocardiography, including difficult to detect findings such as dissection flaps in AD.

References

1 Blaivas M, Sierzenski PR Dissection of the proximal thoracic aorta: a new ultrasonographic sign in the subxiphoid view Am J Emerg Med 2002;20(4):344 348 doi:10 1053/ajem 2002 33006

2 Craen A, Rosario J, Amico K, et al Transthoracic Echocardiographic Findings of Stanford Type AAortic Dissection: A Case Report Cureus 11(11):e6207 doi:10 7759/cureus 6207

3. Gibbons R, Smith D, Mulflur M, et al. 364 Point of Care Ultrasound for the Detection of Aortic Dissections in the Emergency Department Annals of Emergency Medicine 2017;70(4):S143 doi:10 1016/j annemergmed 2017 07 334

4. Gifani P, Behnam H, Sani ZA. A New Method for Pseudo increasing Frame Rates of Echocardiography Images Using Manifold Learning J Med Signals Sens 2011;1(2):107 112

5. Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease JAMA 2000;283(7):897-903 doi:10 1001/jama 283 7 897

6 Mahalingam S, Rajendran G, Balaraman N, et al Stanford - AAortic Dissection Presenting as a Triple Mimic and Role of Point of Care Ultrasound in Deciphering It J Emerg Trauma Shock 2021;14(3):187 189 doi:10 4103/JETS JETS 134 20

7 Mitchell C, Rahko PS, Blauwet LA, et al Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography J Am Soc Echocardiogr 2019;32(1):1 64 doi:10 1016/j echo 2018 06 004

8. Turner SP, Monaghan MJ. Tissue harmonic imaging for standard left ventricular measurements: Fundamentally flawed? European Journal of Echocardiography 2006;7(1):9 15 doi:10 1016/j euje 2005 08 006

9. Wroblewski R, Gibbons R, Costantino T. Point of care Ultrasound Diagnosis of an Atypical Acute Aortic Dissection. Clin Pract Cases Emerg Med 2018;2(4):300-303 doi:10 5811/cpcem 2018 6 38106

10 Zander D, Hüske S, Hoffmann B, et al Ultrasound Image Optimization (“Knobology”): B Mode Ultrasound Int Open 2020;6(1):E14-E24 doi:10 1055/a-1223-1134

11 Zarama V, Arango Granados MC, Bustamante Cristancho LA Importance of Multiple window Assessment for the Diagnosis of Ascending Aortic Dissection Using Point of care Ultrasound: Report of Three Cases Clin Pract Cases Emerg Med 2019;3(4):333 337 doi:10 5811/cpcem 2019 6 43245

Glimpse of Original Research

Diagnostic Ultrasound Measurement ofAcromioclavicular Joint

Position Under Varying Upper Extremity Positions and Loads

T. Motyka, DO, V. Kozlova, BS, H. Pol, PharmD, T. Mitchell, PhD, C. Daniels, Ed.D., RTR, RDMS, RDCS, RVT., G Dogbey, PhD

Affiliation: Campbell University School of Osteopathic Medicine Student Candidates, 2023 Background

Shoulder pain is a common problem, and while 12% is related to the acromioclavicular joint (ACJ), guidelines regarding its diagnosis and treatment are limited1. Disruption of the ACJ typically occurs with direct trauma, as 29% of all shoulder injuries have a direct mechanism, and approximately 53% of these involve the ACJ2. Direct shoulder trauma happens when a person falls onto the ACJ with their arm at their side in an adducted position, especially during collision sports3 To minimize ACJ disruption after such a fall, the acromioclavicular ligament prevents horizontal displacement of the clavicle and the coracoclavicular ligament prevents vertical displacement 4,5. Injury of the ligaments aforementioned can cause instability further leading to shoulder pain.

Various imaging modalities can evaluate the ACJ and are usually chosen based on the suspected injury type 6,7. However, ultrasound is comparable in quality to MRI, CT, and X-ray for ACJ evaluation 1,8 10 In fact, ultrasonography may be superior because it has lower cost, greater availability, higher patient safety, and it

avoids unnecessary irradiation11 . Although there is no standardized imaging protocol to evaluate ACJ injury or pain, ultrasound has been successfully used to measure motion of the ACJ in the anterior-posterior plane in addition to horizontal joint instability5 Other investigators have used ultrasound to explore atraumatic ACJ pathologies and ACJ anatomical variations 12 . Most relevant to this paper, the ACJ has been evaluated for space changes using ultrasound with static measurements and after the application of lateral traction 13 15 The goal of our research is to gather information to standardize ultrasound usage for ACJ evaluation, and then determine if changes in the ACJ space are related to shoulder pain.

Methods

The four cadaver subjects used were preserved in hydrol phenol-based solution, three were male, one was female, with ages ranging from the fifth decade to ninth decade of life. Using the ultrasound transducer directly over the palpated ACJ, both static and dynamic evaluation of the ACJ was performed with and without 20 lbs of force. The microFET 2 Muscle Test Dynamometer was used to measure the applied force during manual application of axial compression, axial distraction, and further adduction. As seen in Figure 1, a linear measurement was obtained by placing the first caliper over the most superior point of the distal clavicular surface (⍺) as it tapers inferomedially. The second caliper was placed at the most inferior portion of the coracoid (��) as it tapers inferolaterally This linear distance measurement (��) was used as the joint space measurement for each condition that was studied. The space between these two landmarks before and after manipulation was then directly measured on the ultrasound monitor image and recorded for analysis.

Results

Results were compared with the joint space measurements between the different upper extremity positions to determine which conditions produce the greatest average amount of joint space change. Significant results were defined as a measurement equal to or greater than 0.10 cm. For our purposes, the result of a positive integer indicates a gain in joint space distance, and a negative integer indicates a loss of joint space distance. ACJ changes were significant, as previously defined, when the upper extremity was started

in a neutral position and then repositioned to simulate internal rotation, abduction, or external rotation. The repositioning demonstrated average joint space changes of -0.24 cm, -0.17 cm, -0.15 cm, respectively There was a change of -0.11 cm produced by abduction to 90 degrees without additional load and with axial compressive force in the 90 degree abducted position. There was increased ACJ space when pushing 20 lb of axial compressive load in a neutral position, resulting in an 0.12 cm gain of distance.

Discussion

These data are consistent with previous ACJ studies, however, they include upper extremity conditions that are not described in current literature. This study is the first to compare multiple upper extremity positions with position changes, traction, and compression. The correlation between ACJ space and instability should be examined for a better understanding of shoulder pain etiologies. The results from this paper can be used as a starting point for this understanding, which will help determine the relationship between shoulder pain, instability, and the ACJ. Ultimately, ultrasound studies should be performed to determine if ultrasound can be used to evaluate the ACJ before and after clinical intervention. If ultrasound can be used as a precise diagnostic tool, clinicians will more accurately identify ACJ pathologies, leading to better patient outcomes and decreased prevalence of shoulder pain.

References

1 Onyambu CK, Mang’Oka DM, Muriithi IM The spectrum of sonographic findings with radiographic correlation in patients with shoulder pain at kenyatta national hospital. Ultrasound Med Biol. 2019;45(1):S38 S38. doi:10 1016/j ultrasmedbio 2019 07 533

2 Enger M, Skjaker SA, Nordsletten L, et al Sports related acute shoulder injuries in an urban population BMJ Open Sport Exerc Med. 2019;5(1):e000551. doi:10.1136/bmjsem 2019 000551

3 Bontempo NA, Mazzocca AD Biomechanics and treatment of acromioclavicular and sternoclavicular joint injuries Br J Sports Med 2010;44(5):361 369 doi:10 1136/bjsm 2009 059295

4 Eschler A, Rösler K, Rotter R, Gradl G, Mittlmeier T, Gierer P Acromioclavicular joint dislocations: radiological correlation between Rockwood classification system and injury patterns in human cadaver species Arch Orthop Trauma Surg. 2014;134(9):1193 1198. doi:10.1007/s00402 014 2045 1

5 Hobusch GM, Fellinger K, Schoster T, Lang S, Windhager R, Sabeti-Aschraf M Ultrasound of horizontal instability of the acromioclavicular joint: A simple and reliable test based on a cadaveric study Wien Klin Wochenschr 2019;131(3):81 86. doi:10.1007/s00508 018 1433 x

6 Aliberti GM, Kraeutler MJ, Trojan JD, Mulcahey MK Horizontal Instability of the Acromioclavicular Joint A Systematic Review Am J Sports Med 2020;48(2):504 510 doi:10 1177/0363546519831013

7. Pogorzelski J, Beitzel K, Ranuccio F, et al. The acutely injured acromioclavicular joint which imaging modalities should be used for accurate diagnosis? A systematic review BMC Musculoskelet Disord 2017;18(1):515 doi:10 1186/s12891 017 1864 y

8 Wengert GJ, Schmutzer M, Bickel H, et al Reliability of high resolution ultrasound and magnetic resonance arthrography of the shoulder in patients with sports related shoulder injuries Todd N, ed PLoS One 2019;14(9):e0222783. doi:10.1371/journal.pone.0222783

9 Peetrons P, Bédard JP Acromioclavicular joint injury: Enhanced technique of examination with dynamic maneuver J Clin Ultrasound 2007;35(5):262 267 doi:10 1002/jcu 20339

10. Kock HJ, Jürgens C, Hirche H, Hanke J, Schmit Neuerburg KP. Standardized ultrasound examination for evaluation of instability of the acromioclavicular joint Arch Orthop Trauma Surg 1996;115(3-4):136-140 doi:10 1007/BF00434540

11 Pogorzelski, J , Beitzel, K , Ranuccio, F et al The acutely injured acromioclavicular joint which imaging modalities should be used for accurate diagnosis? A systematic review. BMC Musculoskelet Disord 18, 515 (2017).

12 Villatte G, Lecointe T, Erivan R, et al Ultrasound Evaluation of Anterior Acromioclavicular Relationship in the Horizontal Plane on 40 Healthy Subjects A New Possibility for Differential Diagnosis of Acromioclavicular Disjunctions Rockwood Stage 3 and 4? A Pilot Study Clin J Sport Med 2018;Volume pub:1 6 doi:10 1097/jsm 0000000000000675

13 Rozin A Ultrasound measurement of the acromioclavicular joint Ann Rheum Dis 2009;68(3):445 446 doi:10.1136/ard.2008.089664

14 Poncelet E, Demondion X, Lapegue F, Drizenko A, Cotten A, Francke JP Anatomic and biometric study of the acromioclavicular joint by ultrasound Surg Radiol Anat 2003;25(5 6):439 445 doi:10 1007/s00276 003 0155 5

15. Marciniak T, Brozynski M, Wit A. Ultrasound guided joint space distance changes during manual traction of acromioclavicular joint in young and healthy adults Postep Rehabil 2015;29(3):13-19 doi:10 1515/rehab-2015-0028

16 K Langlois, H Pillet, F Lavaste, G Rochcongar, P Rouch, P Thoreux & W Skalli (2015) Assessing the accuracy and precision of manual registration of both femur and tibia using EOS imaging system with multiple views, Computer Methods in Biomechanics and Biomedical Engineering, 18:sup1, 1972 1973, DOI: 10 1080/10255842 2015 1072416

Accuracy of Emergency Medicine Resident Performed Point-of-Care Ultrasound

Jeffery Anderson BS, Stacey Rhodes MD, Christine Butts MD and Lisa Moreno-Walton MD Background

Over the last several decades, Point-of-Care Ultrasound (POCUS) has widely demonstrated its effectiveness in the emergency department by reducing lengths of hospital visits, decreasing time to diagnosis, time to definitive care, and increasing cost-effectiveness.1,2,3 The utility of POCUS has led to its incorporation into medical school curricula and emergency medicine residency requirements. Despite the increase in educational exposure, recent literature has shown POCUS teaching varies widely, competency prediction methods are inadequate, and EM residents use POCUS less often than attending emergency medicine physicians.4,5,6 These findings raise questions as to how residents develop proficiency in this field. The objective of this study is to assess the accuracy and proficiency of emergency medicine residents at POCUS.

Methods

A retrospective chart review was conducted on adult patients presenting to the emergency department at University Medical Center New Orleans (UMCNO) who had a POCUS study interpreted by a resident from 12/1/2020 to 6/1/2021. The POCUS modalities included in the study were the Focused Assessment with Sonography for Trauma (FAST) exam, cardiac exam, and aorta exam. The pathologies studied were limited to the primary indications found in the American College of Emergency Physicians’ Emergency Ultrasound Imaging Criteria Compendium. 7 The POCUS exam data was downloaded from QpathTM, a POCUS workflow manager. After uploading the images, the resident would complete a standardized form regarding their findings and interpretation without assistance from faculty or other residents. For each study, the stored MRN was used to locate the patient’s chart, which was reviewed for a gold standard confirmatory study The gold standard confirmatory studies were a CT scan with IV contrast or laparotomy for the FAST exams, an echocardiogram for the cardiac exams, and a CT scan with IV contrast for the aorta exams. Because several of these studies were conducted for educational purposes only, the patient did not always

receive a gold standard confirmatory study. In the event that the patient did not receive any imaging beyond a POCUS examination, the clinical algorithm detailed in Figure 1 was used to determine the patient’s true result. The resident’s interpretation of the POCUS examination was compared to the results from a gold standard study so that sensitivity and specificity values could be computed. Lastly, the abdominal component of the FAST exam was stratified by the Post Graduate Year (PGY) of the interpreting resident.

Figure 1: Abdominal FAST Gold Standard algorithm. A similar process was followed for all other FAST pathologies.

Results

Overall, there were 719 exams (512 FAST, 160 cardiac, and 47 aorta) conducted and stored in QpathTM. From this set, 131 exams (61 FAST, 59 cardiac, and 11 aorta) were excluded due to a lack of an MRN, the absence of a resident’s name, or the patient being under the age of 18. For the 451 remaining FAST studies, the results were organized into three categories: abdominal fluid during the abdominal exam, pericardial fluid during the cardiac exam, and pleural fluid during the thoracic exam. Of the included FAST exams, 138 did not have a gold standard confirmatory study and thus the algorithm in Figure 1 was used. For the 160 cardiac exams, the results were organized into two categories: left ventricle systolic function and the presence or absence of pericardial fluid. Of the included cardiac exams, all were compared to an official echocardiogram interpreted by a cardiologist. The aorta exam assessed the presence or absence of an abdominal aortic aneurysm. All aortic exams were compared to a CT abdomen with IV contrast. The results of the FAST, cardiac, and aorta exam are summarized in Table 1. Lastly, the abdominal portion of the FAST exams was stratified by the resident’s PGY level and summarized in Table 2. Table 1: Residents’ Performance at FAST, Cardiac, and Aorta POCUS.

Discussion and Conclusions

When detecting peritoneal fluid during a FAST exam, left ventricle dysfunction during a cardiac exam, and peritoneal fluid during a cardiac exam, residents performed POCUS exams with a sensitivity comparable to attending physicians. For all six indications, the residents performed the exams with specificities comparable to attending physicians.8,9,10 As demonstrated by the academic stratification data, residents can detect peritoneal fluid during a FAST exam at an attending level by their second year of residency, implying that they become proficient early in their training. While these are encouraging findings, it must be noted that this is a retrospective study, so residents may have discussed the cases before inputting their findings. Additionally, the resident may have interpreted the images correctly but required assistance in obtaining the imaging during the exam. Despite these critiques, the large number of studies during this period show that residents have amble opportunity to practice their technique and become familiar with normal anatomy. Of note, residents fell below their attending counterparts at identifying pericardial fluid during a FAST exam, pleural fluid during a FAST exam, and abdominal aortic aneurysms during an aorta exam. One possible explanation for why residents were able to detect pericardial effusions during cardiac exams, but not during FAST exams is that FAST exams are done in a more acute setting than when cardiac exams are

Table 1: Residents’ Performance at FAST, Cardiac, and Aorta POCUS.

Table 2: Residents’ Performance at Abdominal FAST POCUS stratified by PGY Status

performed. The additional time during a cardiac exam may allow a resident to examine the images in more detail and identify the pathologic fluid. An alternative explanation is a lack of patients presenting with such pathology (16 during cardiac exams and 4 during FAST exams). This lack of exposure to positive findings is highlighted by the fact that of the 588 included exams, 131 had positive exams according to their respective gold standard study. With 63 residents participating, the average resident only saw approximately 2 positive exams during this 6-month period. This finding demonstrates the importance of adequate training opportunities for residents. Resident directors should go beyond the current minimum scan requirement and incorporate simulations where residents can practice obtaining and interpreting images from patients with positive POCUS findings.

References

1 Alpert, E A , Amit, U , Guranda, L , Mahagna, R , Grossman, S A , & Bentancur, A (2017) Emergency department point of care ultrasonography improves time to pericardiocentesis for clinically significant effusions Clinical and experimental emergency medicine, 4(3), 128 132 https://doi org/10 15441/ceem 16 169

2 Lentz, B , Fong, T, Rhyne, R , & Risko, N (2021) A systematic review of the cost effectiveness of ultrasound in emergency care settings. The ultrasound journal, 13(1), 16. https://doi.org/10.1186/s13089 021 00216 8

3 Melniker, L A , Leibner, E , McKenney, M G , Lopez, P, Briggs, W M , & Mancuso, C A (2006) Randomized controlled clinical trial of point of care, limited ultrasonography for trauma in the emergency department: the first sonography outcomes assessment program trial. Annals of emergency medicine, 48(3), 227 235. https://doi org/10 1016/j annemergmed 2006 01 008

4 Stolz LA, Stolz U, Fields JM et al (2017), Emergency medicine resident assessment of the emergency ultrasound milestones and current training recommendations Acad Emerg Med , 24: 353 61

5 Selame, L A , Davis, J J , Ma, I , McFadden, K , Huang, C , Liteplo, A , Goldsmith, A J , & Shokoohi, H (2021) Do scan numbers predict point of care ultrasound use and accuracy in senior emergency medicine residents?. The American journal of emergency medicine, S0735 6757(21)00040 1 Advance online publication https://doi org/10 1016/j ajem 2021 01 037

6. Pouryahya, P., McR Meyer, A.D. and Koo, M.P.M. (2019), Prevalence and utility of point of care ultrasound in the emergency department: A prospective observational study Australasian Journal of Ultrasound in Medicine, 22: 273 278 https://doi org/10 1002/ajum 12172

7. American College of Emergency Physicians (2006). Emergency ultrasound imaging criteria compendium. American College of Emergency Physicians Annals of emergency medicine, 48(4), 487 510 https://doi org/10 1016/j annemergmed 2006 07 946

8 Whitson, M R , & Mayo, P H (2016) Ultrasonography in the emergency department Critical care (London, England), 20(1), 227 https://doi org/10 1186/s13054 016 1399 x

9. Patel, N. Y., & Riherd, J. M. (2011). Focused assessment with sonography for trauma: methods, accuracy, and indications The Surgical clinics of North America, 91(1), 195 207 https://doi org/10 1016/j suc 2010 10 008

10 Moore, C L , & Copel, J A (2011) Point of care ultrasonography The New England journal of medicine, 364(8), 749 757. https://doi.org/10.1056/NEJMra0909487

Resident Section

Ultrasound Has GotYour Back: Posterior Shoulder Dislocations

Jackie Jian, DO and Ashley Voroba, MD

Case Presentation

A 21 year old male with a past medical history of epilepsy presented to the emergency department after a seizure at home complaining of right shoulder pain. The patient reported he had a seizure after not taking his levetiracetam that morning. He denied any recent fevers, chills, cough, chest pain, abdominal pain, nausea, vomiting, or diarrhea.

On physical exam, his vital signs were as follows: temperature 98℉, heart rate 149 beats per minute, blood pressure 139/64 mmHg, respiratory rate 20 breaths per minute, oxygen saturation 96% on room air. He was alert and oriented to person, place and time, and in mild distress. His cardiac exam was tachycardic, with regular rhythm and without murmur. His right upper extremity was internally rotated and adducted, with a gross deformity noted at the right shoulder. His range of motion was limited at the shoulder, however, he had full range of motion at the elbow, wrist and hand. Sensation to light touch remained intact, and his right radial pulse was 2+. The rest of his physical exam was unremarkable.

Case Discussion

Our patient was initially triaged with concerns for supraventricular tachycardia, but a bedside electrocardiogram was performed and the patient’s rhythm was sinus tachycardia. After pain medications, the patient’s heart rate normalized to the 70s.

The patient’s right shoulder exam was suspicious for a shoulder dislocation or fracture. The patient’s initial bedside 2-view shoulder x-ray including a Y-view was interpreted as negative by radiology for both fracture and dislocation.

Figure 1: Xray Y view of right shoulder

Given that we had a high index of suspicion, we performed a bedside point-of-care ultrasound (POCUS). We used a low-frequency curvilinear probe placed over the spine of the scapula and scanned laterally to

identify the glenoid. In the more common anterior shoulder dislocation, the humeral head will appear deep, or further away from the probe. In the case of a posterior dislocation however, the humeral head will appear closer to the probe, which was the case for our patient.

Figure 2: Right Shoulder Posterior US showing posterior shoulder dislocation with the humeral head appears closer to the probe than the scapular spine.

Procedural sedation was performed and the patient underwent reduction of his right posterior shoulder dislocation. On exam post-reduction, the patient no longer had a palpable deformity. We were also able to confirm visually with POCUS that the humeral head articulated properly with the glenoid. The patient was placed in a shoulder immobilizer in neutral position and a post-reduction X-ray was performed, which confirmed successful reduction.

Figure 3: Posterior Shoulder Ultrasound post reduction showing the humeral head at the same level as the glenoid.

Discussion

Posterior dislocation may be missed in up to 50% of cases on AP radiographs because the humeral head appears to be almost normally aligned with the glenoid [1].Ultrasound can be useful for immediate bedside diagnosis of posterior shoulder dislocations and can be used immediately post-reduction for confirmation of reduction, without having to wait for a radiograph. In a systematic review by Entezari et al, seven studies from 1994 to 2017 were reviewed involving 467 patients where 5 studies had a sensitivity and specificity of 100% [2]. Within that systematic review, a study by Ahmadi et al. found a sensitivity of 54% and another study performed by Seyyed Hosseini et al. found a specificity of 60%. In a prospective observational study by Abbasi et al., they found a sensitivity and specificity of 100% in diagnosing shoulder dislocations with POCUS when compared to radiography [3]. In a multicenter prospective study by Secko et al. they found POCUS to be 100% sensitive and specific in diagnosis of shoulder dislocations and found that when compared to radiography, there was a median difference of 43 minutes in time to diagnosis [4].

POCUS has been demonstrated to be an accurate and faster method of diagnosing shoulder dislocation. Musculoskeletal POCUS is easily performed and the structures of interest are superficial, usually at a depth less than 5.0 cm which allow for quick visualization [5]. POCUS allows ED providers to quickly identify dislocations at the bedside and subsequent reduction at the bedside without having to wait for a radiograph. This could improve throughput and reduce patient’s length of stay.

References

1. Gor DM. The trough line sign. Radiology. 2002;224(2):485 486. doi:10.1148/radiol.2242010352

2 Entezari P, Jalili M, Seyedhosseini J, Doosti Irani A, Mirfazaelian H Accuracy of Ultrasonography in Diagnosis of Shoulder Dislocation: A Systematic Review. Adv J Emerg Med. 2019 Oct 16;4(1):e9. doi: 10.22114/ajem.v0i0.285. PMID: 31938778; PMCID: PMC6955034

3 Abbasi S, Molaie H, Hafezimoghadam P, Zare MA, Abbasi M, Rezai M, Farsi D Diagnostic accuracy of ultrasonographic examination in the management of shoulder dislocation in the emergency department Ann Emerg Med 2013 Aug;62(2):170-5 doi: 10 1016/j annemergmed 2013 01 022 Epub 2013 Mar 13 PMID: 23489654

4 Secko MA, Reardon L, Gottlieb M, et al Musculoskeletal Ultrasonography to Diagnose Dislocated Shoulders: A Prospective Cohort Ann Emerg Med 2020;76(2):119-128 doi:10 1016/j annemergmed 2020 01 008

5. Krzyżanowski W. The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part I: Ultrasound anatomy and examination technique J Ultrason 2012;12(49):164 177 doi:10 15557/JoU 2012 0004

POCUS For FemoralArtery Pseudoaneurysm

Sasha Mozelewski, MD, Christianne Jafari, DO, Allison Zanaboni, MD FAAEM and Laura Wallace, MD Washington University School of Medicine in St. Louis

Introduction

The common femoral artery is a commonly used site for vascular access. Puncture-related complications can lead to morbidity and mortality and include perivascular hematoma, pseudoaneurysm, arteriovenous fistula, arterial dissection, arterial thrombus/ occlusion, and retroperitoneal hemorrhage. Presenting

symptoms include ecchymosis, anemia, and hemodynamic instability. Point of care ultrasound, with the addition of color Doppler, can be useful for differentiating between some of these complications.1

Case Report

A 65 year old female with past medical history of CAD, atrial fibrillation on anticoagulation, hypertension, and recent cardiac catheterization via the right femoral artery six days prior presented to the emergency room with complaints of right thigh bruising and swelling since returning home from the procedure. Four days following the procedure the patient noticed right groin swelling with severe pain and mild right foot tingling. Her swelling rapidly progressed over 24 hours leading to decreased ambulation. Her physical exam showed obvious right groin swelling and ecchymosis extending to the mid-thigh with overlying skin ulceration. Right dorsalis pedis pulse was detectable with Doppler signals. Lab evaluation revealed a precipitous drop in hemoglobin from 10.6 g/dL, prior to the catheterization, to 3.6 g/dL. Blood transfusion was initiated and the patient was transferred to a tertiary care center for vascular surgery evaluation. At the tertiary care center, point of care ultrasound imaging was performed.

Imaging

Ultrasonography at the bedside was used to rapidly evaluate the right groin and thigh in the emergency room. These images were obtained starting proximally and moving distally over the area of the femoral artery and its branches.

Watch Mozelewski Video 1

Video 1: Swirling motion showing “yin-yang” sign over a hypoechoic structure adjacent to the pulsatile profunda femoris artery (PFA), suggesting a pseudoaneurysm.

Watch Mozelewski Video 2

Video 2: Color Doppler video with swirling pattern flow, suggesting either a second pseudoaneurysm or continuation of the first. Additionally, a deeper, pulsative, sac-like structure should be evaluated.

Watch Mozelewski Video 3

Video 3: Moving distally and medially, imaging reveals continued arterial component of the deeper sac-like structure, demonstrating a possible further pseudoaneurysm off the second pseudoaneurysm.

Images 1 and 2: CT imaging demonstrated a large, complex, irregular and multiloculated right groin pseudoaneurysm arising from the proximal right profunda femoris artery just distal to the common femoral artery bifurcation as well as a large, incompletely visualized medial right groin hematoma. This was confirmed with CTA imaging.

Discussion

Pseudoaneurysms are the consequence of an arterial wall deficiency or injury, resulting in a local hematoma or sac contained by fibrin wall formation involving two arterial wall layers. Risk factors for pseudoaneurysm formation following vascular access include increased age, female sex, anticoagulant use, and peri-procedure techniques such as inadequate pressure, incomplete access closing, or inadvertent laceration.1,5

Pseudoaneurysms resulting from endovascular procedures have an incidence up to 4.8% and demonstrate significant morbidity due to risk of rupture into the retroperitoneal space or thromboembolism. Other complications include mass effect compromising function of nearby structures and necrosis of overlying tissue.1,5

The deep femoral artery, also known as the profunda femoris artery, is the largest branch off the femoral artery. Pseudoaneurysms at this location typically occur from iatrogenic vascular trauma or femoral fracture, and are quite rare as the artery is protected by the vastus medialis muscle.3 Ultrasound imaging with color Doppler can help differentiate between hematoma, thrombus, and pseudoaneurysm when saccular lesions near a supplying artery are identified. In general, the absence of pulsatility would suggest hematoma, cyst, or seroma. Echogenicity within a vessel, without color flow,

raises suspicion for thrombus. Further support for a thrombus includes lack of vessel compressibility.1 Bidirectional, turbulent flow suggests pseudoaneurysm. A swirling motion pattern, termed the “yin-yang” sign, represents arterial blood flowing toward the probe (red) and entering the sac in systole and away from the probe (blue) exiting in diastole.2

Studies show ultrasonography is a safe, noninvasive, inexpensive, and readily available option for identifying and diagnosing postcatheterization pseudoaneurysm with 94% and 97% sensitivity and specificity, respectively. Limitations include technically limited views due to overlying hematoma, nearby trauma, and inability to completely visualize deep visceral arteries.2

Treatment options include ultrasound-guided thrombin injection, ultrasound-guided compression, or surgical management and repair.5 For this case, percutaneous management was unlikely to be successful due to the size and complexity of the pseudoaneurysm. The patient underwent repair of a right profunda needle defect with drainage of a large medial thigh hematoma and flap repair of the pseudoaneurysm using the right sartorius muscle. She completed an ICU stay postoperatively and was discharged to a rehabilitation center with wound vacuum and drain in place. Her hospital stay was otherwise without complications.

References

1 Chun E J (2018) Ultrasonographic evaluation of complications related to transfemoral arterial procedures

Ultrasonography (Seoul, Korea), 37(2), 164 173. https://doi.org/10.14366/usg.17047

2 Mahmoud, M Z , Al Saadi, M , Abuderman, A , Alzimami, K S , Alkhorayef, M , Almagli, B , & Sulieman, A (2015) "To and fro" waveform in the diagnosis of arterial pseudoaneurysms World journal of radiology, 7(5), 89 99 https://doi.org/10.4329/wjr.v7.i5.89

3 Naouli H, Jiber H, Bouarhroum A False aneurysm of perforating branch of the deep femoral artery Report of two cases Int J Surg Case Rep 2015;14:36 9 doi: 10 1016/j ijscr 2015 07 001 Epub 2015 Jul 10 PMID: 26217914; PMCID: PMC4573209.

4 Tzouma G, Kopanakis NA, Tsakotos G, Skandalakis PN, Filippou D Anatomic Variations of the Deep Femoral Artery and Its Branches: Clinical Implications on Anterolateral Thigh Harvesting Cureus 2020 Apr 28;12(4):e7867 doi: 10.7759/cureus.7867. PMID: 32489722; PMCID: PMC7255544.

5 Rivera PA, Dattilo JB Pseudoaneurysm [Updated 2022 Mar 9] In: StatPearls [Internet] Treasure Island (FL): StatPearls Publishing; 2022 Jan Available from: https://www ncbi nlm nih gov/books/NBK542244/

Ultrasound Guided Procedures

An Introduction to Ultrasound Guided Nerve Blocks in the Emergency Department

Michael Baranowski, MD University of Maryland Medical Center

With the increased usage of point of care ultrasound in the emergency department in recent years, there has been a focus on its use for ultrasound guided regional anesthesia (UGRA) for a variety of conditions 1,2 .

Regional nerve blocks serve as a complement to multimodal pain therapy and an alternative to opioids. Prescription opioids, often given as part of a postoperative pain control regimen, have been implicated in contributing to the opioid epidemic in the United States. Numerous studies have shown that multimodal pain regimens such as regional anesthesia can reduce rates of opioid use, complications related to opioid use, and provide opportunity for enhanced recovery.3,4 UGRA allows for targeted aesthetic use, lower risk of systemic toxicity, and local tissue deformation in cosmetically sensitive areas. UGRA is not without risks however, and as with all ultrasound guided procedures, precautions must be taken in the performance of these procedures. Here we will highlight indications, contraindications, basic setup, and safety for performance of UGRA.

Indications and Contraindications

In the emergency setting, UGRA is primarily utilized for patients with acute injuries. Table 1 highlights the main indications and contraindications for UGRA in the Emergency Department (ED).

Several materials are needed for most UGRA procedures involving large, deep nerve blocks. Smaller, more superficial nerve blocks such as a digital block, or an alveolar block, will not require sterile setup and can be performed by a single provider. To aid in sterility, the provider will need a sterile probe cover with sterile gel, sterile gloves, sterile OR towels, and a chlorhexidine swab for skin cleansing. The overlying skin will need to be anesthetized as well, and this is typically done with 1% lidocaine. The anesthetic used for the actual nerve block should be a longer acting anesthetic. The characteristics of commonly used agents are described in Table 2.

Figure 1: Table 1: Indications and Contraindications for UGRA. Adapted from Regional Anesthetic Blocks.; 20215 Materials

Drug Class Onset Duration Maximum Dose (mg/kg)

Lidocaine 1% (10 mg/ml)

Amide 10-20 min 1-2 hrs 5

Lidocaine 1% w/epi (10 mg/ml) Amide 10-20 min 1-3 hrs 7

Bupivacaine 0.5% (5 mg/ml)

Amide 15-30 min 4-8 hrs 2.5

Ropivacaine 0.5% 5 mg/ml) Amide 15-30 min 4-12 hrs 3

Figure 2: Data Adapted from: Overview of Peripheral Nerve Blocks, UpToDate; Comparison of Commonly Infiltrated Local Anesthetics, UpToDate; Essentials of Regional Anesthesia. 6,7

Long-acting anesthetic is delivered through a 20g or 22g needle. Specific nerve block needles are designed for regional anesthesia with a blunt, or non-cutting tip and increased echogenicity when viewed on ultrasound.8,9 These needles may not be available in all EDs, however As an alternative, a Quinke tip 20g or 22g spinal needle may be used as these have a similar bevel size and contour The length of the needle will be governed by the type of block being performed, however in certain high-risk blocks such as interscalene blocks, a needle no longer than 1 to 2 inches should be used.7 Some larger nerve blocks may require instillation of significant volume (10-50ccs) of anesthetic or anesthetic mixed with sterile saline to achieve adequate anesthesia. These blocks may benefit from use of a second provider with a larger syringe (60cc) and extension tubing. Examples of these nerve blocks include fascial plane blocks such as serratus anterior, erector spinae, or transversus abdominis, or proximal extremity blocks including fascia iliaca, and some brachial plexus blocks.

Setup and Technique

In a 2-provider setup, the primary provider operates the ultrasound probe and directs the needle while the secondary provider assists by holding the syringe and injecting at the direction of the first provider This allows the first provider to focus solely on needle placement. UGRA is typically performed with the high-frequency linear transducer, which capitalizes on the higher resolution image of the probe for identifying superficial structures. A pre-block scan of the site should be performed to identify relevant anatomy and to plan a course for the needle. Figs 1-2. The New York School of Regional Anesthesia (NYSORA) recommends “PART” to optimize ultrasound images:10

P-Pressure: compress adipose tissues and minimize the distance to the target

A-Alignment: of the probe over the area of interest

R-Rotation: turning the probe fine-tune the view of the target

T-Tilting: angling the probe into a perpendicular plane above the target

Figure 2: Cross-sectional image of anterior forearm. Red arrows: arteries. Yellow arrow: median nerve. Blue arrows: fascial plane. Source: Michael Baranowski, MD, University of Maryland Medical Center

Figure 3: Longitudinal image of anterior forearm. Yellow arrows: nerve. Source: Michael Baranowski, MD, University of Maryland Medical Center.

Generally, nerves appear circular, are more hyperechoic than arteries and veins, and will not be compressible (Fig 1). Interestingly, the brachial plexus, when viewed in the transverse axis, often appears more hypoechoic, and can be challenging to differentiate from vasculature. Compressibility, and use of color doppler and pulsed wave Doppler may assist in correctly identifying the relevant anatomy 11

Furthermore, it is important to differentiate between nerve and tendon. Tendons typically move more with joint movement, can be tracked proximally or distally to muscles, and exhibit more anisotropy than peripheral nerves do. Anisotropy describes how much a tissue’s appearance changes due to the angle that

sound waves encounter the tissue. Tendon will have a more variable appearance than nerve as the angle of the transducer is changed.12

The technique utilized is an in-plane technique (Figure 3), rather than axial. This allows proper visualization of the needle tip from the moment it enters the skin until anesthetic is deposited, mitigating misplacement of the needle tip or intravascular/intraneural injection.

Targeted and Fascial Plane Blocks

The two main types of blocks performed under ultrasound guidance are targeted and fascial plane nerve blocks. Targeted nerve blocks rely on deposition of local anesthetic near a nerve followed by diffusion of the local anesthetic around the nerve to obtain adequate anesthesia.11 Ultrasound is used to identify the target nerve and plan a course of the needle to introduce local anesthetic as closely and safely possible. Fascial plane blocks, however, target a potential space between fascial layers. Ultrasound is used to identify the target fascial plane, introduce the needle into this space and local anesthetic is deposited around the fascia where it spreads to nerves within the plane.13

Complications

Providers must be mindful of complications of regional anesthesia and be prepared to manage them. One of the most concerning complications related to local anesthetic use is local anesthesia systemic toxicity (LAST). This syndrome can be caused by supratherapeutic or accidental intravascular injection of local anesthetic. Life threatening manifestations of LAST are primarily neurologic and cardiac in nature, ranging from circumoral numbness and rapidly progressing to agitation, seizure and respiratory arrest.

Figure 4: In-plane technique of needle guidance under ultrasound.

Supratherapeutic concentrations of local anesthetic can induce ventricular arrhythmias, bradycardia, and asystole. Development of any of these symptoms should prompt the provider to stop the injection immediately. Treatment is initially targeted at the specific manifestation and should include cardiac and respiratory support. Intravenous benzodiazepines are used for seizures, and amiodarone is recommended for management of arrhythmias. Lidocaine should be avoided for management of arrhythmias in this setting. Simultaneous to the above treatments, the provider should arrange for lipid rescue with intravenous lipid emulsion therapy. This is administered in a weight-based fashion: if ≤70 kg, give a 1.5 ml/kg IV bolus, followed by an infusion at 0.25 ml/kg/min; if >70 kg give a 100 ml bolus followed by an infusion at of 200-250 ml IV over 15-20 minutes. If there is still significant cardiac toxicity present, the provider may consider giving an additional 1-2 bolus doses and/or doubling of the infusion rate, up to a maximum dose of 12 ml/kg. Once hemodynamically stable, the infusion should be continued for at least 10 minutes. Any ED utilizing local anesthetics or regional anesthesia should have protocols or procedures in place for use of lipid emulsion therapy, and rapid access to this medication.14,15

Peripheral nerve injury, while rare (0.0003-0.0005% occurrence), can often be avoided with pre-block anatomy scanning. Injuries are thought to be caused by direct laceration of nerve fibers, intraneural injection, or direct cytotoxicity of local anesthetic. Treatment is supportive, and 99% of cases resolve within 1 year 2

A specific risk of brachial plexus blocks relates to partial or full paralysis of the ipsilateral phrenic nerve due to local anesthetic effect. These blocks should be avoided in patients with prior phrenic nerve injury Treatment is primarily supportive until the anesthetic wears off.2

References

1 Nagdev A, Dreyfuss A, Martin D, Mantuani D Principles of safety for ultrasound-guided single injection blocks in the emergency department. Am J Emerg Med. 2019;37(6):1160 1164. doi:10.1016/j.ajem.2019.03.045

2 Chang AK, Bijur PE, Esses D, Barnaby DP, Baer J ACEP Policy Statement: Ultrasound-Guided Nerve blocks November 2021. https://www.acep.org/patient care/policy statements/ultrasound guided nerve blocks/. Accessed August 29, 2022

3. Groot L, Dijksman LM, Simons MP, Zwartsenburg MMS, Rebel JR, Phillips AW. Single Fascia Iliaca Compartment Block is Safe and Effective for Emergency Pain Relief in Hip fracture Patients West J Emerg Med 2015;XVI(7) doi:10.5811/westjem.2015.10.28270

4 Chia PA, Cannesson M, Bui CCM Opioid free anesthesia: feasible? doi:10 1097/ACO 0000000000000878

5. Folino TB, Mahboobi SK. Regional Anesthetic Blocks. StatPearls. 2021. https://www ncbi nlm nih gov/books/NBK563238/?report=printable

6. Jeng CL, Rosenblatt MA. Overview of peripheral nerve blocks. UpToDate. https://www uptodate com/contents/overview of peripheral nerve blocks Published 2022

7. Kaye A, Urman R, Vadivelu N. Practical Pharmacology in Regional Anesthesia. In: Essentials of Regional Anesthesia. Cham, Switzerland: Springer; 2018

8. What Needle? Highland EM Ultrasound. http://highlandultrasound.com/what needle. Accessed September 19, 2022.

9 Ip V, Tsui B Equipment for Regional Anesthesia https://www.nysora.com/topics/equipment/equipment regional anesthesia/. Accessed September 20, 2022.

10 Orebaugh S, Kirkham K Introduction to Ultrasound Guided Regional Anesthesia NYSORA https://www.nysora.com/topics/equipment/introduction ultrasound guided regional anesthesia/. Accessed August 29, 2022

11 Ma O, Mateer J, Reardon R, Byars D, Knapp B, Laudenbach A Ultrasound-Guided Regional Anesthesia In: Ma & Mateer’s Emergency Ultrasound. 4th ed. New York: McGraw Hill; 2020.

12 Suk JI, Walker FO, Cartwright MS Ultrasonography of peripheral nerves topical collection on nerve and muscle Curr Neurol Neurosci Rep. 2013;13(2). doi:10.1007/s11910 012 0328 x

13 Chin KJ, Versyck B, Elsharkawy H, Rojas Gomez MF, Sala Blanch X, Reina MA Anatomical basis of fascial plane blocks. Reg Anesth &amp;amp; Pain Med. 2021;46(7):581 LP 599. doi:10.1136/rapm 2021 102506

14 Warren L, Pak A Local anesthetic systemic toxicity UpToDate https://www.uptodate.com/contents/local anesthetic systemic toxicity. Published 2022. Accessed September 20, 2022.

15 Nagdev A, Dreyfuss A, Martin D, Mantuani D Principles of safety for ultrasound guided single injection blocks in the emergency department. Am J Emerg Med. 2019;37(6):1160 1164. doi:10.1016/j.ajem.2019.03.045

Ultrasound Saves

Clot-in-Transit During CardiacArrest

Matthew Hall, MD and Timothy Stokes, MD University of South Alabama

Case Presentation

A 79-year-old male with an unknown past medical history presented to the emergency department in respiratory distress. History was limited secondary to the severity of his illness. Per EMS, the patient called 911 after having sudden onset chest pain and shortness of breath. EMS found the patient in respiratory distress and cyanotic. They applied a non-rebreather but were unable to raise the oxygen saturation above 85% and he was found to be hypotensive to 85/40.

Upon arrival to the ER the patient appeared toxic with tachypnea, diaphoresis and was moaning in pain, clutching his chest. His cardiac and pulmonary exams were normal, and his extremity exam revealed a unilaterally swollen left leg. Shortly after arrival the patient became unresponsive and went into PEA. ACLS was initiated and multiple cardiac views were obtained.

Cardiac and IVC views revealed multiple echogenic masses in the right atrium and IVC which demonstrated swirling and “ping-ponging” consistent with a clot-in-transit. During pulse checks additional views were obtained which showed an enlarged right ventricle on the parasternal long axis and a D-sign on the parasternal short axis.

A bolus of tPA was given as pulmonary embolism was the presumed cause of the arrest. Prolonged ACLS was continued post tPA administration, but unfortunately ROSC was never achieved.

Discussion

Point-of-care ultrasound has radically changed the way we are able to evaluate patients in real-time, especially in resuscitations where other imaging modalities are impractical. Cardiac ultrasound in particular can be useful for ruling out reversible causes during cardiac arrest. Signs of pulmonary embolism on bedside ultrasound during cardiac arrest can change management.

In our case we see a clot-in-transit in the right heart unattached to any cardiac structure, free-floating and at risk of embolization into the pulmonary arteries. Our case likely represents a fatal massive pulmonary embolism, with part of the venous thromboembolism still actively advancing into the pulmonary arteries. Clot-in-transit is defined in the literature as mobile echogenic material temporarily present in the right heart chambers on its way to the pulmonary circulation. It is a rare ultrasound finding and is associated with a mortality rate of 44.7% due to imminent embolization and obstructive shock.[1] It is unclear if clot-in-transit is a marker of disease severity (such as massive pulmonary embolism) or contributes to mortality itself. There is no specific consensus on treatment, but options include anticoagulation alone or anticoagulation combined with systemic thrombolysis, surgical embolectomy, and/or catheter directed thrombolysis.

Interestingly, there are three types of right heart thrombi, A, B, and C.[2] Type A describes a clot-in-transit either in the RA/RV, the SVC/IVC, or stuck in a patent foramen ovale. Type B describes mural thrombi attached to the wall of either the RA or RV, and are thought to have a lower mortality rate than type A. Finally, Type C describes thrombi that share morphology with cardiac myxomas. Our patient had a type A thrombus with a clot visualized both in the RA and the IVC.

Although visualization of a clot-in-transit is uncommon, other signs that can signify a possible pulmonary embolism include McConnell’s sign, right ventricular dilation, acute tricuspid regurgitation, the D sign, and the 60/60 sign. Imaging in our patient was limited as it was obtained during cardiac arrest, however right ventricular dilation and a D sign were present.

Right ventricular dilation is most accurately assessed in the apical 4 chamber view. The A4CH allows comparison of the size of the RV and LV, with the RV normally being 2/3rd the size of the LV. As the RV approaches the size of the LV, suspicion for right heart strain increases. Mild dilation ranges up to an RV/LV ratio of 1, moderate ranges to 1.5, and severe dilation is a ratio > 1.5.[3] It is important to note that as cardiac arrest continues over time, some right heart dilation is expected, which can make it challenging to differentiate between acute right heart strain and right heart dilation secondary to cardiac arrest.

A D sign was also present in our patient and is classically taught as a marker of right heart strain. The D sign, visualized on parasternal short axis, occurs when right sided pressures overcome the left side. It is described as the RV pushing the LV septal wall causing the LV to form a “D” shape. Beware however, that a D sign can be seen in chronic right heart strain as well.

In summary, ultrasound can be a valuable tool during cardiac arrest. One should pay attention to possible signs of pulmonary embolism including clot-in-transit, RV dilation, and the D sign as seen in our patient. Clot-in-transit is an uncommon finding with an increased mortality an no specific treatment consensus.

References

1 Chartier L, Béra J, Delomez M, et al Free floating thrombi in the right heart: diagnosis, management, and prognostic indexes in 38 consecutive patients. Circulation. 1999;99(21):2779 83.

2 Kashfi S, Nasser MF, Soleiman A, Sharma S, Koripalli VS, Sharma S Clot In Transit in a Patient with Protein S Deficiency Eur J Case Rep Intern Med 2022 May 5;9(5):003355 doi: 10 12890/2022 003355 PMID: 35774736; PMCID: PMC9239027.

3 Fields JM, Davis J, Girson L, Au A, Potts J, Morgan CJ, Vetter I, Riesenberg LA Transthoracic Echocardiography for Diagnosing Pulmonary Embolism: A Systematic Review and Meta Analysis J Am Soc Echocardiogr 2017 Jul;30(7):714 723.e4. doi: 10.1016/j.echo.2017.03.004. Epub 2017 May 9. PMID: 28495379.

4 Shah DP, Min JK, Raman J, Lodato JA, Van Kley D, Lang RM, Ward RP Thrombus-in-transit: two cases and a review of diagnosis and management J Am Soc Echocardiogr 2007 Oct;20(10):1219 e6 8 doi: 10 1016/j echo 2007 01 041 Epub 2007 Jun 20. PMID: 17583475.