Emergency Ultrasound Section Newsletter - August 2007, Vol 11, #3
Emergency Ultrasound Section Meeting at SA
Make plans to attend the Ultrasound Section Meeting!
Monday, October 8, 2007
11:30 am - 2:00 pm
Cirrus, Sheraton Seattle
Please note that the meeting is NOT at the Convention Center this year. The Sheraton is the hotel where the ACEP Board and Council meetings will be held and it is across the street from the Convention Center. In order to accommodate the expected attendance for the Ultrasound Section meeting, we had to move to the Sheraton.
Be sure to check the schedule on site as meeting times and location could change.
This year’s agenda includes election of new section officers as well as an opportunity to catch up with fellow section members. The educational portion of Scientific Assembly runs from October 8-11. We hope to see everyone there. www.acep.org/sa.
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From the Chair
Robert Jones, DO, RDMS, FACEP
It is hard to believe that summer is already here. The kids are out of school, the temperature has already hit the 90 degree mark in Cleveland, and the new interns and residents have begun. A few months ago when I wrote my article for the spring newsletter, Cleveland had just been hit hard with a spring snowstorm. I wrote the article after finishing shoveling the walkways around the house. After I finish this article, I will be heading out to the back yard to cut the grass. Although I have never been a big fan of cutting the grass, I will take cutting grass any day over shoveling show in freezing temperatures.
It is probably safe to say that summer passes too quickly, so we need to start looking toward the fall. This means preparing for ACEP’s Scientific Assembly and the section meeting. Hopefully, everyone will be able to attend since we have a lot to discuss. We will be having short presentations on ultrasound education for medical students and the experience of emergency physicians in Iraq with bedside ultrasound (see corresponding articles in this newsletter). In addition, we will provide updates on where we stand and where we are going with issues such as accreditation.
The issue of accreditation still remains in the spotlight. Although we are not currently a target of the insurance companies, it was universally agreed upon by the section leaders that being proactive here is essential. As I see it, we have only a few options here:
- Do nothing and wait until we are the target of insurance companies. While it may take years for this to happen, there is obviously a huge downside to a "wait and see" approach.
- Work with AIUM (a leading multi-specialty organization) to develop an accreditation process. From an accreditation standpoint, this would be the ideal situation since they are nationally recognized. The problem here is that even though our standing within the ultrasound community has improved dramatically in recent years, we still have the stigma of "focused" ultrasound hanging over our heads. Getting AIUM to accept our educational guidelines will be a challenge. Accepting their educational guidelines is not an option since this is not in the best interest of the practicing emergency physician. We will continue to work with AIUM and we remain cautiously optimistic.
- Work with ACEP to develop an accreditation process. While this would seem like an easy solution, it may not be the best solution. This would take a great deal of work to put together and it would still be a challenge to get insurance companies to accept our guidelines. The same leaders that are opposed to "focused" ultrasound within AIUM are probably the same ones who act as imaging consultants for the insurance companies.
- Work with the critical care community to put together a joint EM-critical care organization that will act as our accreditation body. The critical care community is now aggressively pursuing bedside ultrasound and they share a lot of our visions. More importantly, they are experiencing the same political obstacles that we have encountered.
- Work with ACEP to make a case on our behalf to the insurance companies that an accreditation process may not be anyone’s best interest here. For whatever reason(s), focused ultrasound has been a difficult concept for traditional providers to understand and accept. Some have looked at it as an inferior imitation of what is done by radiology, cardiology and ob. It needs to be looked at as a clinically relevant, focused application of this technology to improve clinical accuracy at the bedside and to assist in high-risk procedures.
We are currently in the process of writing a resolution that would ask ACEP to support us here in order to protect our practice rights. In the meantime, we will continue to explore all options so that ultimately, we will provide a solution that is in the best interest of all emergency physicians.
Moving on to the ACEP Ultrasound Section web page, we will be moving forward with putting together lists of emergency ultrasound fellowships, mini-fellowships, and rotations for emergency medicine residents and medical students. ACEP has given us the green light to go ahead with this. The lists will be posted on the section’s web page and will serve as a resource for all section members. If you haven’t submitted information about your fellowship, mini-fellowship, or emergency ultrasound rotation for residents/students, then please do so. Information can be sent to me c/o firstname.lastname@example.org.
Lastly, Scientific Assembly also means election time. Elections will be held at the section meeting for the following positions: chair-elect, councilor, and alternate councilor. If you have any interest in running for one of the positions, now is a good time to throw your hat into the ring. Section positions are open to all members regardless of previous experience.
I wish everyone a happy and relaxing summer. I look forward to seeing everyone at Scientific Assembly. As always, if anyone has any questions or concerns, please feel free to contact me c/o email@example.com.
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Scan Days in Thailand: An International Ultrasound Elective
Artur M. Treyster, MD
Chief Resident, North Shore University Hospital
This past winter I spent two months working in the emergency department (ED) at Ramathibodi hospital in Bangkok, Thailand. The purpose of my elective was to witness the development and advances of the Thai emergency medicine residency program, which is only a few years young, and to learn about the patient population & pathology that fills their ED. A main focus of mine was to teach basic emergency ultrasound to the Thai residents. To assist me in my endeavor, SonoSite had graciously provided me with a portable machine (Micromaxx) for the length of my trip. I spent the month prior to my departure designing a workshop curriculum with the ultrasound core faculty at North Shore. My Ultrasound Workshop design consisted of 30-minute lectures covering Trauma, AAA, RUQ, DVT, Cardiac, and US-guided central line placement.
My first surprise was that all of the Thai residents spoke English, with varying degrees of proficiency. They tend to present at conferences using Microsoft PowerPoint in English, but then lead their discussions in Thai. I found it beneficial to stick to my slides and have as little improvisation as possible. This enabled the residents to follow the educational objectives. "Improv" at times ended in confusion or worse snoozing! The highlight of these workshops was the actual hands-on experience, for which I would use residents as models. Most of the Thais were very slim and proved to be excellent scan models with easily identifiable anatomy.
Since "practice makes perfect," my goal was to limit the workshops to no more than 6 residents at a time, this number was ideal in making sure that every resident practiced each exam type numerous times. I initially taught about 10 workshops with residents from 3 different residency sites. As my time passed I started noticing that when I was working in the department more residents were approaching me not to perform the initial scan but to confirm/verify their findings. Due to the high incidence of thalassemia, Hepatitis B & C, and the advanced stages of disease uncovered at diagnosis, the incidence of hepatobiliary pathology (cancer, stones, cholecystitis) is many times higher than in the United States. A quick RUQ ultrasound proved essential in expediting diagnosis and disposition in a large number of patients. These same problems often manifested themselves in metastatic effusions, either lung or pericardial, which again are crucial to diagnose quickly in an emergency setting. I saw numerous patients presenting with acute dyspnea that were managed more efficiently when the FAST demonstrated a pleural effusion, or quick echo revealed a large effusion with tumor emboli in the heart. I was exposed to ultrasound pathology that I may never see practicing in the U.S., and the Thai physicians were able to utilize the findings of their ultrasound exams to improve patient care even after brief training sessions. Emergency medicine has really exploded in Thailand over the past 3 years, with their first EM residency class graduating this year. As these residents leave Bangkok and move on to fulfill their obligations in the rural provinces, emergency ultrasound holds great promise for the growth of emergency medicine nationwide. I truly enjoyed my time in Bangkok. My memories of karaoke with my fellow Thai residents and the "godfathers" of Thai emergency medicine will stay with me for a very long time. I look forward to participating in many more projects in the future where we can help other countries progress with the use of emergency ultrasound and advance emergency medicine throughout the world. We have as much to gain from these experiences as those we are trying to teach.
I would like to encourage residents from other programs to get involved with "Resident Echoes." Please contact me firstname.lastname@example.org
Christopher C. Raio, MD, RDMS
Director, Emergency Ultrasound
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SOAP Update July 2007
Lawrence A. Melniker, MD, MS, FACEP
Director, Sonography Outcomes Assessment Program
- Prospective Observational Trial of Common Carotid Intima Media Thickness Assessment in the Evaluation of Patients with Acute Chest Pain in the Emergency Department
This trial is evaluating the predictive value of PLUS measurement of the intima-media thickness (IMT) of the carotid arteries in ED patients with suspected Acute Coronary Syndrome. It will completed in the Fall 2008 and assess the predictive value of IMT, using the resultant calculated vascular age, both, alone and in conjunction with multiple cardiac biomarkers.
- Prospective Observational Trial of Inferior Vena Cava Caliber, Variability, and Indices in Healthy Pediatric Patients: Generating a ‘Growth Curve’ for IVC.
This trial will enroll a cohort of healthy children ages 2-12 and assess the size of the inferior vena cava during a normal state of hydration. The measurement will be used to generate an IVC "growth curve." Once validated, the growth curve will be employed prospectively on a cohort of undifferentiated patients presenting to the ED with varied hydration states. The first phase will be completed in the winter of 2008.
- Prospective Observational Trial of Common Carotid Intima Media Thickness Assessment in the Evaluation of Patients with TIA and CVA in the Emergency Department
- Prospective Observational Trial of Common Carotid Intima Media Thickness Assessment in the Evaluation of Patients with Syncope in the Emergency Department
These two studies will use similar methodologies as the current IMT trial in suspected acute coronary syndrome; they will begin in the spring of 2008.
Trials in Development
- Comparative Trial of Sonographic Assessment of Inferior Vena Caval Filling with Central Venous Pressure Manometry in Suspected Sepsis, Severe Sepsis, and Septic Shock
- Comparative Trial of Common Carotid Intima Media Thickness Assessment with Coronary Angiography, Cardiac Computerized Tomography, and Cardiac Magnetic Resonance Imaging
- Prospective Observational Trial of Sonographic Confirmation of Endotracheal Tube Placement in the Emergency Department
- Prospective Observational Trial of Sonographic Confirmation of Endotracheal Tube Positioning in the Critical Care Setting
- Randomized Controlled Trial of PLUS for Dyspnea in the Emergency Department
Institutions interested in any of the trials planned or in development may contact me directly c/o email@example.com.
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Continuous Quality Management and Expanding the Use of Clinical Sonography:
Paradigm Shift to Enhance Quality of Care and Patient Safety – An Introduction
Lawrence A. Melniker, MD, MS, FACEP
Vice Chairman for Quality Improvement
Department of Emergency Medicine
New York Methodist Hospital
Several representatives of the Emergency Medicine community had the great fortune of participating in the 1st World Congress on Ultrasound in Emergency & Critical Care Medicine in June 2005. When we arrived, many referred to what we did as "Emergency Ultrasound" or "Emergency Medicine Ultrasound," but the last night, a few of us were discussing the Congress and decided - we were wrong!
We realized that what we do with ultrasound machines in the ED is a large slice of a pie called "Clinical Sonography" or "Clinician-performed Sonography." It represents nothing less than an historic paradigm shift in how we clinically assess our patients. Resistance has been and will continue to be stiff, just as the generalization of the stethoscopy was resisted 100 years ago, but the technological cat is out of the bag and running – the shift is stoppable! My daughter, Haley, is 3 years old; should she decide to follow our footsteps into medicine, I believe she may never own a stethoscope, but she will have a "Personal Sonographic Assistant."
Those of us in Emergency Medicine, who use Clinical Sonography, are right in the middle of and have a responsibility to promote this transformation. Some will develop innovative ways to use sonography; others will conduct research to confirm its effectiveness; many will teach our colleagues how to perform and integrate sonography into the clinical decision-making process; but all must use this technology to improve quality of care and promote patient safety.
For many reasons, this last point – quality and safety – while always on our minds, must be our verbal and written mantra in all aspects of our promotion of Clinical Sonography. Whenever possible, the description of each application should be articulated in the context of better and safer care; the rollout of new techniques should be presented as quality improvement and/or patient safety initiatives; research protocols and grant applications should include indicators of quality of care, both, positive and negative, to facilitate a discussion of patient safety enhancement; and teaching opportunities, including lectures, demonstrations, and hands-on skill labs should be broadly laced with the available evidence of enhancement of quality of care and patient safety.
This is critical, because continuous quality management is a hot topic: we face an expanding list of CMS, JC, and ORYX indicators; audits for appropriate and timely treatment; and Pay-for-Performance is right around the corner. Our challenge -- Where does Clinical Sonography fit in these manifold and complex processes?
Furthermore, the traditional providers of imaging services expend less energy today trying to stop us from purchasing machines and using them; instead, they promulgate the false notion that we provide substandard training and imaging, for which we should not be reimbursed. They are lobbying lawmakers for the authority to credential us and accredit our imaging practices. Therefore, we also must demonstrate the quality of our teaching, performance, and interpretation of Clinical Sonography. Finally, we will fight any attempt by any other specialty to govern the practice of Emergency Medicine. See the ACEP Council Resolution, the Performance and Interpretation of Imaging Studies Protection Plan, submitted by the Ultrasound Section and published in this newsletter.
This is the first in a series of articles on the importance of the relationship between Continuous Quality Management and Clinical Sonography. Any members of the Section with questions or concerns they would like addressed in future articles may contact me c/o firstname.lastname@example.org and contributing articles may be forwarded to the newsletter editor c/o email@example.com.
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AIUM Ultrasound Practice Forum 2007 Liaison Report
Vivek S. Tayal, MD, FACEP
ACEP Liaison to AIUM
I am pleased to have represented the American College of Emergency Physicians with Michael Blaivas, MD at the AIUM US Practice Forum in Baltimore, MD on April 23, 2007. This was the 3rd meeting of this multidisciplinary group that is addressing ultrasound issues in medicine in the United States. A summary of pertinent findings follows.
- Quality in ultrasound was the theme of this year's conference, headlined by a Keynote address by the Dean of Medicine at University of Maryland, Dr. E. Albert Reece. He quoted all of the IOM reports since the 1998 report, "To Err is Human."
- Prior US Practice forums – No clear action has been taken on prior Compact US and US practice forums. The categorization proposed during the first forum in 2005 had a designated "emergency" category that we felt would be advantageous if adopted.
- Specialty interactions with AIUM -- The following organizations reported on interactions with AIUM
- American Association of Clinical Endocrinologists
- They negotiated a clinical accreditation agreement with AIUM, and have their own certifying and accreditation process which costs $1700
- American College of Emergency Physicians
- Dr. Blaivas spoke regarding our continuing interaction with AIUM over the FAST guideline negotiated during the last 3 years
- American Society of Breast Surgeons
- Unclear, but they have some interaction with AIUM. They have their own certifying exam, which costs $750
- Musculoskeletal Ultrasound Society
- Working with and separately from AIUM
- Society for Reproductive Endocrinology and Infertility
- Just starting and interested in working with AIUM
- Insurance/ Accreditation
- Outpatient imaging procedures accreditation – all payors including BCBS, United Healthcare, are requiring external accreditation to use ACR, ICL, or AIUM accreditation.
- Ultrasound (growth rate 10%) has been hurt by grouping with complex imaging (CT, MRI, PET, Nuclear –growth rate 20-30%)
- Medicare is focusing on payment with possible reduction of the practice expense of US because of its lumping with CT, which has tremendous utilization rates, thus causing the practice expense to drop per patient.
- Medicare Quality measures – only one quality measure in 2007 utilizes ultrasound (stroke requiring carotid imaging)
- HR 583/SB 1042 – US radiation safety act moves to require certification of all technologists. We believe this will severely exacerbate the shortage of technologists, and possibly create a dangerous precedent for further certification of physicians beyond primary Board Certification.
- Communication via a monograph created by the US Section to payors and governmental entities regarding the existing quality and credentialing standards (guidelines) in emergency ultrasound.
- Lobby against HR583 which will exacerbate technologist shortages, and possibly set a precedent for the government accreditation and certification.
- We would suggest to the sponsors to delete ultrasound from the bill, which is its purest form, is a radiation safety bill.
- Allow Emergency Ultrasound Section to develop plans for a future web-based accreditation system either through
- A Third-party sanctioned by ACEP
- Be aware the certifications issues still persist regarding ultrasound providers. Though credentialing is the current process suggested by ACEP to show competence, we may need to show competence beyond Board Certification in the future.
I was waiting for slides of the conference from AIUM, but I feel I cannot delay my report any longer. I appreciate the opportunity to represent ACEP, and look forward to working with the College to further our interests in emergency ultrasound.
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Point-of-care Pediatric Ultrasound
Jim Tsung, MD, MPH
Bellevue Hospital Center
New York University School of Medicine
I am grateful to past Ultrasound Section Chair Paul Sierzenski, MD, RDMS, FACEP for inviting me to speak to the ACEP ultrasound section last year in New Orleans about using point-of-care ultrasound for pediatric fractures on Emergency Ultrasound Day, (don’t forget-October 15th!). Since then, my colleagues and I have been steadily gaining more experience with using ultrasound for pediatric fractures. Our clinical bottom line: very good for displaced shaft fractures, but be careful when looking at the ends of the bones where the contours change. If in doubt, always check the normal contralateral side.
For some of the pediatric specific-fractures, such as toddler’s fractures and non-displaced growth-plate fractures—scanning for these fractures can be tricky, and checking the contra-lateral side is useful (sometimes a nutrient vessel may be confused as a nondisplaced toddler’s fracture; plus don’t forget to look for soft-tissue changes, especially for growth plate fractures). However, it will be difficult to skip the x-rays for these types of fractures. Of course, someone may come-up with an ultrasonographic work-around for these fractures in the future (maybe 3D?). At present, most of my pediatric colleagues are highly skeptical that diagnostic ultrasound for fractures will be truly useful in the emergency department aside from guiding fracture reduction, but for those of us that participate on international medical missions where there may not be x-ray capability available, ultrasound should come in very handy. Don’t leave home without one!
Every year, I am heartened and excited to see more and more abstracts related to point-of-care pediatric ultrasound use at both emergency medicine and pediatric scientific meetings. So for those doing pioneering research on point-of-care pediatric ultrasound use, keep up the great work!
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Ultrasound Journal Watch
McIlrath ST, Blaivas M, Lyon M. Patient follow-up after negative lower extremity bedside ultrasound for deep venous thrombosis in the ED. Am J Emerg Med. 2006;24(3):325-328.
Reviewer: Eric W. Snyder, MD, MS
Methods: This was a prospective, observational study. Patients with a negative ED lower extremity ultrasound were divided up into "low risk" and "high risk" groups. High risk patients were scheduled to have a repeat ultrasound 5-7 days after their initial ED ultrasound. Low risk patients did not have repeat ultrasounds scheduled. 3 month follow-up was attempted on all patients.
Results: 159 patients had a negative ED ultrasound done by an ED physician and were enrolled for follow up. 54% were considered high risk and 64% of these patients were contacted successfully. 28% of the patients contacted received a follow-up ultrasound. 29% were told by their PMD that a repeat ultrasound was unnecessary. 21% forgot to follow-up. 8% did not follow-up for financial reasons. 16% did not follow-up because they felt better. 5% could not arrange a follow-up study. Only 2 patients were ultimately diagnosed with a DVT, one at the 7 day followup and one after 9 months.
Discussion: Being able to accurately rule out or rule in a DVT in the ED by an ED ultrasonagrapher is an important skill. This study aimed to determine the follow-up of patients who were sent home following an EP-performed negative lower extremity ultrasound. This was a small study done by EPs who were credentialed per the 2001 ACEP Ultrasound guidelines. Although only 2 of the 159 patients were ultimately found to have a DVT (and only 1 of those at 7 days), follow-up was only possible for 54 patients. Furthermore, the study demonstrated that patient follow-up was poor (ie, only 28% of high-risk patients ultimately returned for a second ultrasound as recommended).
Implications: The results of this study indicate that very clear return instructions need to be given. Patients need to be instructed that a repeat ultrasound is essential even if their symptoms improve or their PMD does not deem it necessary.
Volpicelli G, Mussa A, Garofalo G, et al. Bedside lung ultrasound in the assessment of alveolar-interstitial syndrome. Am J Emerg Med. 2006;24(6):689-696.
Reviewer: Parveen Parmar, MD
Introduction: The authors of this study set out to see if bedside ultrasound could be used to detect a number of pulmonary conditions that result in "alveolar-interstitial syndrome" or AIS. AIS is defined as "several heterogeneous conditions with diffuse involvement of the interstitium and impairment of the alveolocapillary exchange capacity, which leads to more or less severe respiratory failure." AIS would thus include a very diverse set of conditions, including acute respiratory distress syndrome (ARDS), interstitial pneumonia, pulmonary fibrosis, or acute pulmonary edema. Previous research in this area has suggested that comet tail B lines, or vertical artifacts fanning out from the lung-wall interface and spreading up to the edge of the screen, are seen in patients with AIS. These B lines are thought to be due to thickened interlobular septa and extravascular lung water.
Methods: Over a 10-month period, 300 patients were enrolled for this study in an academic hospital in Turin, Italy. Enrollment criteria are unclear, but these appear to be inpatients admitted to a medicine ward. All patients underwent a chest x-ray and also underwent lung ultrasound during the first 48 hours of their stay. X-rays were performed with standard equipment and reviewed by radiologists who were unaware of the clinical picture or findings of the lung ultrasound.
Ultrasounds were performed using a GS 50 portable ultrasound unit with a 3.5 MHz transducer. Five trained physicians (3 emergency physicians and 2 radiologists) performed these scans, blinded to the x-ray findings and clinical data of the patient. The chest wall of each patient was divided into 8 areas. Each side was divided into 2 anterior and 2 lateral portions (each anterior and lateral portion had an upper and lower half), and a scan was performed in each area. At least two separate physicians scanned each patient to assess interobserver variability. A scan was considered positive if B lines, as defined above, were found in at least two scans on each side, suggesting AIS.
Multiple comparisons are made in this study, including ultrasound vs. x-ray, ultrasound vs. CT scan, and ultrasound vs. clinical outcome. "Clinical outcome" was based on patient history and presentation, x-rays, and multiple other tests done during hospital stay including echocardiography, pulmonary function tests, etc.
Results: A total of 295 patients received pulmonary ultrasounds and chest x-rays that were included in this study. Five were eliminated due to uninterpretable ultrasound or x-ray. In 18 cases, thoracic computed tomography was also performed, at the discretion of the admitting physician. These data were also analyzed.
Of the 295 patients, 160 were diagnosed with cardiac or pulmonary conditions, and 75 had a final diagnosis of AIS. Fifty-nine had congestive heart failure, 6 had pulmonary fibrosis, 3 had pulmonary tuberculosis miliaris, three had bilateral diffuse pneumonia, and one had ARDS. The patients that did not have a final diagnosis of AIS in this group of 160 patients had diagnoses including isolated pneumonia, cancer, pulmonary embolism, pleurisy, asthma, and cor pulmonale (several had more than one diagnosis).
When the results of ultrasound were compared to the chest x-ray, the sensitivity was 85.7%, and the specificity was 97.7% for diagnosing AIS. When compared to CT, the ultrasounds in all 18 cases corresponded to the findings of the CT scans. When compared to patient outcome, ultrasound had a sensitivity of 85.3% and a specificity of 96.8%.
Discussion: While it is interesting to explore the sonographic findings associated with diffuse pulmonary conditions, it is unlikely that this study will change clinical practice for several reasons. First, there are some intrinsic problems with the paper, including the post hoc comparison of ultrasound to CT, and the lack of clear enrollment criteria for the study.
But most importantly, the composite condition "AIS" includes many diverse conditions with very different acute interventions that it is hard to imagine diagnosing "AIS" in the ER will ever prove useful. Chest x-ray is widely available and gives much more useful clinical information (i.e., differentiating between fibrosis and pulmonary edema). Potentially, in a situation where radiography is unavailable this could serve as a useful back up tool.
Ferre RM, Sweeney TW. Emergency physicians can easily obtain ultrasound images of anatomical landmarks relevant to lumbar puncture. Am J Emerg Med. 2007;25(3):291-296.
Reviewer: Kwame Donkor, MD
Introduction: This study evaluated whether EPs can use ultrasound to gather pertinent information and images of the necessary landmarks for an LP in a wide spectrum of patients in an efficient and timely manner.
Methods: This was a prospective observational study done by EPs after taking a course in US imaging and performing 10 practice scans. Patients who were = 18 years were eligible for enrollment in this study irrespective of their chief complaint at the time of ER visit. Patients were excluded if they were non-English speaking or were unwilling to participate in the study. The EP rated the ease of landmark palpation as easy, moderate, difficult and impossible. Six images were obtained from each patient placed in the lateral decubitus or sitting position including a midline, right and left paramedian views using both linear array and curvilinear probes. It appears outcome measures were visualization of the spinal processes and another deep soft tissue structure (e.g. ligamentum flavum) in the midline view and visualization of the laminae and another deep soft tissue structure.
Results: Seventy-six patients participated in this study. High quality images defined as identifying 4/5 relevant anatomical structures were obtained in 73 patients (96%). With the paramedian approach using a 3 MHz curved array probe, the laminae and ligamentum flavum were identified in all 76 patients compared to 74 (97.4%) patients when the 7.5MHz linear array probe was used. With the midline approach using a 3MHz curved array probe, the spinous processes and ligamentum flavum were identified in 74 (97.4%) patients versus 73 (96.1%) using the 7.5MHz linear probe. With the midline approach, images were acquired in mean time of 54.7+/-58s (95% CI 41.3-68.1) with the 3MHz curved probe and 60.5 +/- 54.55 (95% CI 41.48.1-73) with the 7.5MHz linear array probe. With paramedian approach, images were obtained at a mean time of 45.1+/- 44.5s (95% CI 34.9-55.4) with the 3MHz curved probe and 56.8 +/- 57s (95% CI 43.8-69.9 with the 7.5MHz linear array probe. There was no statistically significant difference in acquisition time based on probe type or type of approach. The authors also showed that as the BMI increased above 30, the time taken to acquire images increased.
Comments: EPs do not currently have many alternatives to unsuccessful LP other than initiating treatment and admitting for fluoroscopic guided LP. This study demonstrated that a paramedian approach with either the curved or linear probe could provide information for needle insertion as well as the midline approach. However, the quality of images suffered and time to acquire images increased as the BMI of the subject increased. Several limitations should be noted. These include no independent verification of landmarks, time to acquisition of images, or quality of images. In addition, it would have been important in this study to know whether the positioning (sitting versus lateral decubitus) of the patient played any role in the quality of images or ease of acquisition of landmarks. Because US-guided LP will be of potential benefit in patients with elevated BMI, it is important to stress a few points: there is no way to evaluate benefit without a head-to-head study assessing US-guided LP versus LP without US guidance in patients with elevated BMI. It may turn out that using US-guidance may add very little in the performance of LP in patients with very high BMI. Other limitations in this study included a small sample size, not actually performing an LP, and questionable operator experience. However, this study suggests that US may be a useful adjunct to the performance of an LP and should be validated in a prospective randomized control trial.
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This publication is designed to promote communication among emergency physicians of a basic informational nature only. While ACEP provides the support necessary for these newsletters to be produced, the content is provided by volunteers and is in no way an official ACEP communication. ACEP makes no representations as to the content of this newsletter and does not necessarily endorse the specific content or positions contained therein. ACEP does not purport to provide medical, legal, business, or any other professional guidance in this publication. If expert assistance is needed, the services of a competent professional should be sought. ACEP expressly disclaims all liability in respect to the content, positions, or actions taken or not taken based on any or all the contents of this newsletter.