Monthly Archives: June 2013

SonoStudies: Thoracic Ultrasound for Pulmonary Embolism #FOAMed

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Thoracic ultrasound is one of the most highly changing and advancing applications of bedside ultrasound, and the research that has been published on the utility of this application for our patients cannot be ignored. It can aid (and is better than chest Xray) in pneumothorax evaluation, pleural effusion assessment (only need 15cc of fluid to see it on ultrasound!), pneumonia evaluation, and pulmonary edema assessment. See prior posts here, here and here with literature referenced to read about all of that – trust me it’s worth it!). Of course, if you add cardiac echo to your evaluation for acute pulmonary embolism, the studies suggest it helps to look for McConnells sign and RV dilation and strain (which is a bad prognostic indicator for PE). Recently, there was a case report published in J of EM of a PE-in-transit diagnosed by bedside echo, leading to expedited care and ability to know the cause of suden cardiac arrest in a patient. For a clip of what it may look like for a “mobile mass” seen in RA, click here. Another study in J of EM was done concluding that ED bedside ultrasound echo results  predicted PE adverse outcomes.

Seeing RV dilation/strain can help but are seen mainly when the patient is hemodynamically unstable. Could thoracic ultrasound identify subsegmental pulmonary embolism in patients who are not hemodynamically unstable? Interesting question and I truly hope so…

So, if that wasnt enough, now it can help with pulmonary embolism evaluation??? What?! That is great and i hope that this teaser of a study below can be repeated and found to be valid. It would be great. Now, there have been a few others, like a meta-analysis showing that thoracic ultrasound should not be ignored when suspecting PE, a review of chest ultrasound for pulmonary diseases showing its utility, and a case report and review by the Italians (who are huge researchers in thoracic ultrasound where I listen to pretty much everything they say about it).

This recent study in Annals of Thoracic Medicine, physicians in Turkey evaluate the use of bedside ultrasound for the evaluation of pulmonary embolism. The abstract is below:

“OBJECTIVES: The diagnosis of pulmonary embolism (PE) is still a problem especially at emergency units. The purpose of study was to determine the diagnostic accuracy of thoracic ultrasonography (TUS) in patients with PE.

METHODS: In this prospective study, 50 patients with suspected PE were evaluated in Department of Pulmonary Diseases of a Training and Reasearch Hospital between January 2010 and July 2011. At the begining, TUS was performed by a chest physician, subsequently for definitive diagnosis computed tomography pulmonary angiography were performed in all cases as a reference method. Other diagnostic procedures were examination of serum d-dimer levels, echocardiography, and venous doppler ultrasonography of the legs. Both chest physician and radiologist were blinded to the results of other diagnostic method. Diagnosis of PE was suggested if at least one typical pleural-based/subpleural wedge-shaped or round hypoechoic lesion with or without pleural effusion was reported by TUS. Presence of pure pleural effusion or normal sonographic findings were accepted as negative TUS for PE.

RESULTS: PE was diagnosed in 30 patients. It was shown that TUS was true positive in 27 patients and false positive in eight and true negative in 12 and false negative in three. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of TUS in diagnosis of PE for clinically suspected patients were 90%, 60%, 77.1%, 80%, and 78%, respectively.

CONCLUSIONS: TUS with a high sensitivity and diagnostic accuracy, is a noninvasive, widely available, cost-effective method which can be rapidly performed. A negative TUS study cannot rule out PE with certainty, but positive TUS findings with moderate/high suspicion for PE may prove a valuable tool in diagnosis of PE at bedside especially at emergency setting, for critically ill and immobile patients, facilitating immediate treatment decision.”

From the BLUE protocol by Lichtenstein on how to distinguish the various etiologies of shortness of breath, an algorithm was given (see below) which includes the utility of bedside ultrasound for pulmonary embolism diagnosis:

A Profile: anterior A lines bilaterally only – absence of interstitial syndrome – with lung sliding

A’ profile: A profile without lung sliding

B profile – anterior B lines bilaterally with lung sliding

B’ profile – B profile without lung sliding

A/B profile – A lines on one side and B lines present on the other side (asymmetry)

C profile – anterior consolidation (shred sign)

Normal – A profile without PLAPS

PLAPS = posterolateral alveolar and/or pleural syndrome

Thoracic US and the BLUE protocol

A good presentation on thoracic US for pulmonary embolism can be found here:

SonoGallery: Free downloadable 3D & 4D OBGYN ultrasound cases and images #FOAMed

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I love free stuff, especially when it is for the purpose of education. PanoramaScan is a site that sells their images and courses, but also provides a great group of free downloadable images and cases in OBGYN ultrasound. From normal fetal anatomy to molar twin pregnancy in 3D and 4D – it has some great images that are amazing to view. This truly puts a different perspective on maternal-fetal medicine.

These free downloads come with a short and brief description of the video. It is perfect for those of us who have short attention spans!

As they state in their website: “Our mission, for the past eight years, is to successfully deliver state-of-the-art 4D ultrasound and Doppler education in maternal fetal medicine (MFM) –obstetrics and gynecology (OB GYN) through our huge library of obstetrics and gynecology ultrasound courses, ultrasound cases, ultrasound teaching files, sonograms (sonography images and ultrasonography videos),ultrasound web casts, ultrasound pdf documents and ultrasound ppt presentations.”

SonoTips & Tricks: The upper quadrants of the FAST scan #FOAMed

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Happy Monday everyone! I mean, Tuesday!! Ugh! Well, if you were wondering where I’ve been, or even if you didn’t notice, I’ve had a busy couple weeks. From the many shifts that was full of interesting ultrasound cases (which you know I’ll share with you soon!) to graduating another stellar group of emergency residents, credentialing them in EM Ultrasound after 3 great years of training and a competency test, and hopefully soon to hear about the amazing pick-ups and lives saved in their future careers with the use of their great clinical judgement and bedside ultrasound. Im sure you love those busy weeks as much as we do, so i thought I would post something that would be a bit of positivity and highlight a group that I believe in: ACEP Ultrasound Section.

I’ll start with what I’ve said before: “2013 is the YEAR OF ULTRASOUND – and for good reason – there are only a few tools that give us such immediate information that can save a life. The ACEP US Section is the go-to site for everything you want to know about starting an US program, credentialing in ultrasound, the policies and politics, and is the home of SonoGuide – an amazing educational resource for bedside ultrasound, and the EMSONO: Ultrasound Test. It is also where we add our entries for their newsletter that goes over tips and tricks, cases, and all things ultrasound in the news. We recently wrote an article for the ACEP Ultrasound Section Newsletter – which is available for all members of the ACEP US Section – and I highly recommend becoming a member – it’s totally worth it. To continue to entice you, i will include our latest entry below – with a few additions in the end. For a set of links to online education in bedside ultrasound, go here. And, for our last entry into the Newsletter on Social Media in EM Ultrasound and the amazing tools out there to learn it for free, go here.”

Now, let’s talk about the FAST scan. It was a TRUE pleasure to record a podcast recently with Dr. Scott Weingart (aka, my hero) on EMCrit (twitter: EMCrit), and writing this article with our ultrasound fellow, Dr. Viveta Lobo, describes some of what was spoken about.

The focused assessment with sonography in trauma, or FAST exam, is undoubtedly the most widely used bedside ultrasound application in emergency medicine. With its incorporation into the ATLS trauma protocol, the FAST exam is performed immediately after the primary survey simultaneously with other resuscitative efforts. It is also a component of the RUSH protocol for patients with unexplained shock. Trauma patients often present with multiple injuries, and significant bleeding can occur without obvious changes in vitals signs. Medical patients can present intoxicated, altered, delirious, or demented all of which will limit the physical exam. The primary purpose of the FAST exam is to rapidly detect free fluid and hemorrhage in the peritoneal, pericardial and pleural spaces. There may be difficulties in obtaining adequate views, and we hope to discuss a few pearls to minimize them.

As with all ultrasound applications, familiarity with technique and patient anatomy, knowledge of common pitfalls, practice, and appreciating technical limitations are important errors to avoid. In general, the FAST exam is not “fast” – it can take up to 3-4 minutes to perform.1 The patient should be supine (or Trendelenberg) with low ambient light, with a low frequency probe used (the phased array probe provides the additional benefit of visualizing between the ribs and getting into the subxiphoid region more easily for the cardiac view). Even with the best technique, the FAST scan will only visualize 25 cc or more of thoracic free fluid and 500cc or more of intraperitoneal free fluid.2

The Right Upper Quadrant (RUQ)

RUQ

The RUQ is the most sensitive region for free fluid in comparison to the other FAST views.3 In my view, the RUQ should be divided into 3 zones.

1. Above/Below the diaphragm,
2. Morrison’s pouch (hepato-renal recess)
3. Paracolic gutter: Around the inferior hepatic edge/inferior pole of kidney

The key is to know your landmarks, and STOP, STAY and widely FAN through each zone well, adjusting your depth as necessary to keep the area of interest centered on your screen. Click Here for a Video. Start high to stay and fan (anterior to posterior) around the diaphragm. Then, SLIDE down into another rib space, stop, stay and fan around the entire kidney. An additional rib space may be necessary to evaluate the paracolic gutter.

Tips for RUQ Diaphragm View :

The liver may be easily seen, but the diaphragm can be more difficult, especially if it’s behind a rib shadow. Have the patient take in a deep breath. This lowers the diaphragm into your view and allows visualization of the thoracic cavity for hemothorax/pleural fluid as well as sub-diaphragmatic peritoneal fluid. Visualization of the spine shadow travelling in the lower part of the screen will normally stop at the diaphragm with a mirror image artifact illustrated in the thoracic cavity.

2-TT Imagespineshadow

However, if the spine is able to been seen above the diaphragm– this is pathognomonic of pleural fluid, and also known as the “V-line.”4Click Here for a Video.

3-TT Imagevline

Tips for RUQ Morrison’s Pouch (Hepato-Renal Recess) View:

If rib shadows get in the way, using the same trick above of patient inspiration can help. There are also a few false positive “traps” here.

First, the double line sign, seen around the kidney capsule as hyperechoic double lines with hypoechoic material in between, can be mistaken for free fluid.5 However, free fluid will not be surrounded by hyperechoic lines and will not be in a contained structure.

4-TT ImageVine
Second, edge artifact from the liver/kidney interface occurs due to ultrasound physics and sound wave transmission between structures of different densities. It is seen as a dark thin line tracing off the edge of this interface extending to the bottom of the screen. Click Here for a Video. This differentiates it from free fluid, which will not extend past the liver.Click Here for a Video.

5-TT ImageRUQFFinMP

Tips for RUQ Paracolic Gutter View:

This is where free fluid can be seen first amongst all the different zones of the RUQ view.6The most important tip is to not forget to view this area. You will often have to slide your probe more inferior to obtain this view. Decrease the depth to look around the hepatic edge and inferior kidney pole, and evaluate the region with slow fanning. Click Here for a Video.

6-TT ImageParaCOlicFF

The Left Upper Quadrant (LUQ)

The LUQ is less sensitive for free fluid than the RUQ for varying reasons. First, the LUQ is opposite the side of the sonographer, which can make it technically difficult to obtain an adequate view. Also, the spleen is smaller than the liver and, thus, the acoustic window is lessened.

7-TT Imagestomachsabotage

The stomach commonly obstructs the view as well. The LUQ should also be divided into 3 zones:

1. Above/Below the diaphragm,
2. Spleno-Renal recess,
3. Paracolic gutter: Around the inferior pole of kidney

Tips for the LUQ view
In addition to the various RUQ view tips and tricks as stated above, the LUQ diaphragm view also requires tips to avoid “stomach sabotage”. There are two ways around this: oblique the probe to have the indicator angled toward the gurney and/or slide your probe to the posterior-axillary line away from the plane of the stomach.

8-TT ImageLUQFFAbove

Look out for Part 2 of FAST Tips and Tricks, in the next newsletter where we talk about maximizing your cardiac views.

For additional material, images, and cases on the E-FAST, go here.

Another great review of FAST with excellent references here.

And, of course, saving the best for last – Cliff Reid and The Ultrasound Podcast discusses how to “earn your vaginal stripes” about the EFAST – go here.

Jacob Avila of 5MinSono did a great false positive blog on FAST here.

References
1.     Boulanger BR, McLellan BA, Brenneman FD, et al. Emergent abdominal sonography as a screening test in a new diagnostic algorithm for blunt trauma.
J Trauma. Jun 1996;40(6):867-    874.
2.     Branney SW, Wolfe RE, Moore EE, et al. Quantitative sensitivity of ultrasound in detecting free intraperitoneal fluid. J Trauma. Aug 1995;39(2):375-380.
3.     Chambers JA, Pilbrow WJ. Ultrasound in abdominal trauma: an alternative to peritoneal lavage. ArchEmerg Med. Mar 1988;5(1):26-33.
4.     Atkinson P, Milne J, Loubani O, et al. The V-line: a sonographic aid for the confirmation of pleural fluid. Crit Ultrasound J. 2012;4(1):19.
5.     Sierzenski PR, Schofer JM, Bauman MJ, et al.
The double-line sign: A false positive finding on the focused assessment with sonography for trauma (FAST) examination. J Emerg Med. 2011;40(2):188-189.
6.     Rozycki GS, Ochsner MG, Feliciano DV, et al. Early detection of hemoperitoneum by ultrasound examination of the right upper quadrant: a multicenter study.
J Trauma. Nov 1998;45 (5):878-883.

SonoStudy: Meta-analysis: History & Physical exam with Ultrasound for extremity fractures #FOAMed

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I keep thinking about this study published in the Jan 2013 issue of Academic Emerg Med by Dr. Nikita Joshi et al…. for a few reasons… so I thought i would highlight it on SonoSpot and spark some discussion to get your thoughts too. (Get full article here). First off, it’s about a condition that I see in the emergency department on every shift, so it’s incredibly relevant. And, it involves imaging, specifically ultrasound, and how it can benefit the patients with this problem from cost savings to quicker diagnoses and treatment. Finally, the results actually surprised me. Not because ultrasound seemed to be just as good as radiographs, but that they weren’t better. But, I should say that it was a meta-analysis and quite difficult to compare and the study subjects in the meta-analysis all had radiograph proven fractures, and I wonder what would have happened if the xrays were negative but the bedside ultrasound was positive, proven by a gold standard, like CT scan???….  Who am I kidding?! That would involve too much cost, radiation, and time in the emergency department….. Oh wait, I get it….I guess I understand the importance of this study now. There have been quite a few studies on the topic in the last couple years – go here, here, here, here, and here – which makes it really exciting.

The authors start by stating that radiographs do miss fractures:

“The typical work-up of the injured patient generally involves a medical provider obtaining a history and physical examination, often followed by radiologic imaging. However, many times the radiologic imaging may be negative or inconclusive, which calls to question whether the imaging contributed to the management or outcome of the patient. Studies have shown that often the imaging obtained is unnecessary and results in radiation exposure to patients and increased ED wait times.[2]….There’s a low rate of positive radiography when assessing for fractures as evidenced by a retrospective review by Bentohami et al.,[3] in which only 50% of upper extremity x-rays showed fractures, and another study by Heyworth,[4] which showed 15% of patients with ankle injuries had documented fractures on x-ray. In the study by Stiell et al.,[2] patients with ankle injuries had midfoot fracture rates of 4.3%, and 9.3% had malleolar fractures. Therefore, 50% to 95% of extremity x-rays can be avoided without missing fractures.”

Ok, so we know this. Xrays arent great, so why get them? If you think the fracture would need reduction due to a displacement, then ok. But, wouldnt that be possible by physical exam as a deformed extremity so that you’d know to Xray that one? If the extremity is not deformed, but tender and swollen, why not just splint? Isnt that what you would do anyway if the xray was negative due to a high clinical concern for “occult fracture”?

The authors then follow this up with one of my favorite paragraphs on the topic:

“Bedside US has the potential benefits of reducing radiation exposure, costs, and pain, while potentially improving ED patient throughput and satisfaction. This reflects on the original purpose of developing CDRs for extremity fractures. Use of bedside US can help triage patients during a busy ED shift by quickly assessing for the presence of fracture as an adjunct to the normal history and physical examination. It can also aid nurses and physicians who may require more resources for reduction of a fracture.[11] EPs have become more adept at fracture diagnosis through independent review of US and radiographic imaging, and many researchers have examined the ability of EPs to obtain US imaging and diagnose fracture.[12, 13] Additionally, bedside US has excellent diagnostic test characteristics when performed by EPs compared to radiologists in the diagnostic evaluation for soft tissue infections,[14] cholecystitis,[15] pneumothorax,[16] or ruling out ectopic pregnancy.[17]“

Love it. See the abstract below and read the entire article to see their limitations and methodology here.

Objectives

Understanding history, physical examination, and ultrasonography (US) to diagnose extremity fractures compared with radiography has potential benefits of decreasing radiation exposure, costs, and pain and improving emergency department (ED) resource management and triage time.

Methods

The authors performed two electronic searches using PubMed and EMBASE databases for studies published between 1965 to 2012 using a strategy based on the inclusion of any patient presenting with extremity injuries suspicious for fracture who had history and physical examination and a separate search for US performed by an emergency physician (EP) with subsequent radiography. The primary outcome was operating characteristics of ED history, physical examination, and US in diagnosing radiologically proven extremity fractures. The methodologic quality of the studies was assessed using the quality assessment of studies of diagnostic accuracy tool (QUADAS-2).

Results

Nine studies met the inclusion criteria for history and physical examination, while eight studies met the inclusion criteria for US. There was significant heterogeneity in the studies that prevented data pooling. Data were organized into subgroups based on anatomic fracture locations, but heterogeneity within the subgroups also prevented data pooling. The prevalence of fracture varied among the studies from 22% to 70%. Upper extremity physical examination tests have positive likelihood ratios (LRs) ranging from 1.2 to infinity and negative LRs ranging from 0 to 0.8. US sensitivities varied between 85% and 100%, specificities varied between 73% and 100%, positive LRs varied between 3.2 and 56.1, and negative LRs varied between 0 and 0.2.

Conclusions

Compared with radiography, EP US is an accurate diagnostic test to rule in or rule out extremity fractures. The diagnostic accuracy for history and physical examination are inconclusive. Future research is needed to understand the accuracy of ED US when combined with history and physical examination for upper and lower extremity fractures.

Nice job Nikita!

UltrasoundPodcast recently did a podcast on Distal radius fractures.

A great video of distal radius fractures can be seen here:

In case you’re curious about how easy it is to visualize a fracture by ultrasound, see image below. That bright white line is bone, and that break is …a break.

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SonoMedStudent: Ultrasound for Anatomy & Physiology – the lectures & the conference #FOAMed

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The First Conference on Ultrasound in Anatomy and Physiology Education took place in March 2013. It was coordinated by a guru to medical student ultrasound education, Dr. Richard Hoppmann (a Dean and a proponent of US in medical education), with some of his good friends in ultrasound education, including one of my favorites, Dr. Michael Blaivas, an emergency physician that was one of the Godfather’s to bedside ultrasound and proving through his insane number of research studies that emergency physician (and others) can and should be performing bedside ultrasound for their patients.

It’s exciting, it’s relevant, and it matters. Doesn’t that feel good to your medical education?! Of course it does! What is even better, is that the lectures can all be found online for FREE here. Thank you Dean Hoppmann, and looking forward to the Second Conference coming in September. Sign up now!

To read more on Ultrasound in Medical Education and insights from the best of the best at AIUM and more, go here.

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