SonoTutorial: Appendicitis assessment by ultrasound #FOAMed #FOAMus

In a recent article in Insights into Imaging, there is a great pictorial and descriptive review of the how-to of appendicitis assessment by ultrasound. The authors are radiologists from the UK and they provide an excellent description of its assessment. As they state, if appendicitis is not evaluated in patients with right lower quadrant pain or any of the other signs of appendicitis (either by the Alvarado Score or other decision rule… or even just your clinical judgement) complications can occur: “Potential complications include perforation, peritonitis, abscess formation and death. Because of atypical presentations and the risk of potential complications, imaging is often requested. In children, this imaging technique is usually US.” For SonoSpot cases for appendix US, go here. For SonoSpot studies’ reviews in appendicits, go here.

Their specific teaching points:

• A step-wise technique improves the chances of visualisation of the appendix.
• There are often several causes for the non-visualisation of the appendix in children.
• A pathological appendix has characteristic US signs, with several secondary features also identified.
• There are multiple common differentials to consider in the paediatric patient.
Their technique as described in the free article published:
1. Ask where it hurts and start there
2. Graded compression
3. Find the appendix using specific landmarks (psoas muscle and iiacs vessels)
4. Look for signs of appendicitis (noncompressible, tubular, >6mm diameter, aperistaltic) – other signs described below

“Setting the scene: contact with the patient and parents

When meeting the paediatric patient for the first time, the patient should be asked where the point of maximum tenderness is located. The examination is explained to the patient. The patient is usually accompanied by a parent or guardian. In optimal conditions, the patient is fasted and has a full bladder to help in the exclusion of any ovarian or other pelvic pathology.

Graded compression US

The scan is continued with a planar higher frequency probe, which allows higher resolution of more superficial structures. The frequency used depends on the size and age of the child (between 5 and 12 MHz).

Step 1:

Displacing small bowel loops out of the way
Normal bowel loops are displaced by gentle compression of the anterior abdominal wall using the US probe. These loops should be easily compressed and displaced away. The displacement of the bowel structures should allow the visualisation of the iliac vessels in the right iliac fossa as well as the psoas muscle. Two-plane scanning is performed (longitudinal and transverse).
Step 2:

Visualisation of the ascending colon and caecum
The ascending colon is visualised as a non-peristalsing structure containing gas and fluid in the right side of the abdomen. The probe is then moved inferiorly toward the caecum, using repeated compression and release to express gas and fluid from the bowel (Fig. 1a, b). The right psoas muscle should also be visualised (Fig. 2). The adjacent terminal ileum should be identified as a compressible structure that is undergoing peristalsis.

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Fig. 1

Longitudinal (a) and transverse (b) views using high frequency linear-array probe showing the caecum (small white arrows in b) and ascending colon in a 15-year-old girl
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Fig. 2

Longitudinal image showing the caecum and ascending colon, as well as the adjacent psoas muscle posteriorly (small white arrows) in a 15-year-old girl
Step 3:

Identification of the appendix
Once the caecum has been seen, the appendix should be visualised arising from it, separate to the terminal ileum (Fig. 3). The appendix should be followed along its whole length. A normal appendix should measure 6 mm or less in diameter from outside wall to outside wall. It should have a thin wall (less than 3 mm), be empty or gas/faecal-filled and compressible, and there should be no evidence of hypervascularisation [2326].

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Fig. 3

A normal appendix is seen draped over the iliac vessels in a 10-year-old girl. This is thin-walled, measuring less than 6 mm in diameter (A width of 3 mm). The caecum can be seen in continuity with the appendix superior to it
Step 4:

Assessment for features of acute appendicitis
An abnormal appendix can have any of the following characteristics which should be actively considered:

  • Compressibility: in acute appendicitis, the appendix is non-compressible [24]. One caveat here is perforation when the appendix can become compressible.
  • Maximum diameter: a maximum diameter of greater than 6 mm is considered abnormal (Figs. 4 and 5) [52425].
  • Wall thickness: a single wall thickness of 3 mm or more is considered abnormal (Fig. 6) [2427].
  • Target sign appearance: this is caused by a fluid-filled centre (hypoechoic centre), surrounded by a hyperechoic ring (mucosa/submucosa) which is surrounded by a hypoechic muscularis layer giving a target sign on axial imaging (Fig. 7a, b) [1528].
  • The presence of an appendicolith (this will appear as an echogenic focus with posterior acoustic shadowing) (Fig. 8a, b) [1528].
  • Vascularity: peripheral appendiceal wall hyperaemia is seen in the early stages of acute appendicitis (Fig. 9a, b); this may not be seen with progression to necrosis [1529].
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Fig. 4

Longitudinal view of a thickened, oedematous appendix measuring 10 mm in diameter with surrounding increased echogenic omentum in an 8-year-old boy with confirmed appendicitis. Absent intraluminal gas is noted
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Fig. 5

Transverse view of a thickened, oedematous appendix measuring 10 mm in diameter in an 8-year-old boy with confirmed appendicitis. Again, surrounding omentum of increased echogenicity is noted
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Fig. 6

The wall of this oedematous appendix measures 4 mm in an 8-year-old boy with confirmed appendicitis. Increased echogenic omentum is seen adjacent to the appendix
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Fig. 7

a A transverse view of an inflamed appendix in a 15-year-girl, showing the target sign appearance. bSimilar appearances in an 11-year-old boy. This target sign comprises a hypoechoic fluid-filled centre (white arrow), inner hyperechoic mucosal/submucosal ring (white asterisk), and outer hypoechoic ring (dashed white arrow)
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Fig. 8

Appendicoliths (labelled) causing posterior acoustic shadowing in two patients, a 15-year-old girl (a) and a 10-year-old boy (b). The thickened, fluid-filled appendix is labelled in b (small white arrows)
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Fig. 9

a Increased Doppler signal in a thickened, oedematous appendix in an 8 year-old-boy. b Similar appearances noted in a 10-year-old girl. The increased Doppler signal indicates hyperaemia
Secondary features can be observed around the inflamed appendix; these should be actively sought:

  • Free fluid or abscess in the periappendiceal region (Fig. 10) [61528].
  • Increased echogenicity of the adjacent periappendiceal fat (Fig. 11) [61528].
  • Enlarged mesenteric lymph nodes (Fig. 12) [15].
  • Thickening and hyperechogenicity of the overlying peritoneum (Fig. 13).
  • Dilated hyperactive small bowel from secondary small bowel obstruction (Fig. 14).
  • Focal apical caecal pole thickening or thickening of the adjacent small bowel can be seen as a secondary response [630].
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Fig. 10

Small pocket of free fluid in the region of the appendix (white arrow) in a 10-year-old girl with confirmed appendicitis
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Fig. 11

Omental fat with increased echogenicity with a mass-like appearance (small white arrows) in a 12-year-old boy with confirmed appendicitis
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Fig. 12

Multiple lymph nodes (arrows) in the mesentery of the periappendiceal region in an 8-year-old girl with confirmed appendicitis
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Fig. 13

Increased echogenic free fluid in the right iliac fossa (indicating pus) with adjacent thickening of the peritoneum in a 2-year-old girl with confirmed appendicitis
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Fig. 14

Loops of dilated, fluid-filled small bowel in a 2-year-old girl with confirmed appendicitis. Echogenic free fluid is seen adjacent to the bowel indicating pus (white arrow)
It is not uncommon that the appendix cannot be identified. There are varying rates quoted in the literature for the appendix being seen, between 24.4 % and 69.3 % [61323]. In this situation, it is important to actively assess for the secondary features often seen which may help direct further management. Repeating the examination after a few hours has been shown to significantly increase the sensitivity of US [31].
Read on more to hear about the complications of appendicitis,  the causes of inadequate visualization, and other etiologies as seen on ultrasound for right lower quadrant pain. Trust me, its worth the viewing.

SonoTips & Tricks: The FAST scan: The Cardiac views #FOAMed

Finishing the ultrasound QA sessions that we do every week at Stanford, I was reminded about how bedside ultrasound is a tool that helps when resources were limited. If you hadn’t heard, there was an Asiana Airlines plane crash at San Francisco International Airport with over 180 patients requiring medical care, 55+ of which came to Stanford. Luckily, we just added 4 new SonoSite EDGE ultrasound machines to our 4 MTurbos and 3 GE Vscan systems the week before – and they sure were used well! The FAST scan was used as a screening tool and to help prioritize those who would go to the CT scanner. Once, again, it is important to know how to do it and do it well.  Our latest insert in the ACEP Ultrasound Section newsletter is below – on the FAST scan – the Cardiac sections. The prior entry was on the FAST scan: The Upper Quadrants ( go here. ) – And Ultrasound Podcast recorded with Cliff Reid about it this week too!

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.”

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.

By Viveta Lobo, MD and Laleh Gharahbaghian, MD, FACEP

As discussed in our last entry, the FAST exam is undoubtedly the most widely used bedside ultrasound application used in emergency medicine. Its incorporation in the ATLS revised protocol, the RUSH exam, and several other published protocols, makes it an invaluable screening tool for intra abdominal injury causing hemoperitoneum, cardiac injury with pericardial effusion, and unexplained hypotension.

We will continue our discussion of the FAST scan by reviewing the cardiac views, and relay some tips and tricks for each. Refer to the previous newsletter for tips onscanning the right upper quadrant (RUQ) and left upper quadrant (LUQ).

The Cardiac Views:

The traditional cardiac view obtained as part of the FAST exam is the subxiphoid view. The main focus of this view in the FAST exam is to evaluate for evidence of cardiac injury by evaluating for pericardial effusion and/or cardiac tamponade. The phased array probe is placed in the subxiphoid space medially, applying pressure to go under the xiphoid process and flattening out the probe while aiming caudally.

Tips for the Subxiphoid View: 

TT1 1. Use your liver as an acoustic window. 
TT2
Sound waves will travel through liver to the heart, allowing you to visualize the heart. Often one can even place the probe slightly to the right of the xiphoid process, to allow for better liver visualization, and then adjust your depth to be able to look past the liver to the heart. Without the liver in view, gas scatter will affect your image acquisition.


2. Visualize both the inferior and superior pericardial borders, to completely evaluate for pericardial effusion or, rarely, loculated pericardial effusions. It is possible for one area to have pericardial effusion and not the other. Click Here for a Video.

3. Have the patient take a deep breath and hold it. When you notice that the heart is far from the probe, and you find yourself adjusting your depth to more than 20cm, having your patient take a deep breath will lower the heart closer to the probe, improving visualization. Click Here for a Video.

TT3

Despite the subxiphoid view being the traditional view for the FAST exam, the parasternal long view is becoming more of the ‘go-to’ window to evaluate for pericardial effusion. This may be due to several very relevant clinical factors: You simply cannot get a good subxiphoid view. An injury, foreign body, or abdominal pain does not allow for subxiphoid probe placement/pressure. Or you can differentiate pericardial fluid from pleural fluid in the parasternal long view

Tips for Parasternal Long View:
As far as patient positioning, if you’ve already evaluated the RUQ and LUQ (so as to not affect free fluid evaluation) and the patient is able to turn into a left lateral decubitus position, it will help bring the heart closer to the chest wall for visualization. This can be difficult, or impossible, in trauma patients, so the below tips may help:

TT4 1. Start high and start medial - Place your phased array probe just next to the sternum, starting just under the clavicle. If you don’t see the heart there, slide down a rib space, and fan through that space to find the heart. Continue sliding down rib spaces, until you find it.

2. Slowly change the angle of your probe (up and down) when you’re assessing each rib space as described above. ‘Slowly’ is the key word here. If you’re angling downward too much in a rib space and see the PSL heart, you may need to just slide down a rib space. If that makes the image worse, slide back up.

3. Slowly rotate your probe while keeping the angle described above (clockwise/counterclockwise depending on whether you use the right shoulder or the left hip to direct your probe marker). Rotate until you visualize the longitudinal view of the left side of the heart.

4. Slide your probe medially/laterally only if you need to in order to center the aortic and mitral valves on your screen.

5. Ensure adequate depth in order to distinguish a left sided pleural effusion from a pericardial effusion. This will allow visualization of the descending thoracic aorta seen in its transverse view just deep to the heart, which is your landmark in differentiating pleural effusion from pericardial effusion. Pleural effusion will travel posterior to the aorta while pericardial effusion will travel anterior to it (and possibly circumferentially around the heart).TT5
TT6

TT7Lastly, it can be very difficult in both subxiphoid and parasternal long views to differentiate epicardial fat pad from pericardial effusion. One tip: epicardial fat is seen anteriorly and has echogenicity within it, while pericardial effusion is seen posteriorly or inferiorly and is anechoic, but can travel anteriorly if large enough to become a circumferential pericardial fluid collection. Despite this tip, clinical correlation is needed.

Look out for Part 3 of the FAST Exam: The Pelvis, in the next newsletter. Until next time, happy scanning!

For a set of links to online education in bedside ultrasound, go here. Another post on Social Media in EM Ultrasound and the amazing tools out there to learn it for free, go here.”

References
1. Ma OJ, Mateer JR, Ogata M, et al. Prospective analysis of a rapid trauma ultrasound examination performed by emergency physicians. J Trauma. 1995; 38:879-85.
2. Wherrett LJ, Boulanger BR, McLellan BA, et al. Hypotension after blunt abdominal trauma: the role of emergent abdominal sonography in surgical triage. J Trauma. 1996;41:815-20.
3. Schiavone WA, Ghumrawi BK, Catalano DR, et al. The use of echocardiography in the emergency management of nonpenetraing traumatic cardiac rupture. Ann Emerg Med. 1991;20:1248-50.
4. Rozycki GS, Feliciano DV, Ochsner MG, et al. The role of ultrasound in patients with possible penetrating cardiac wounds: a prospective multicenter study. J Trauma. 1999;46:543-52.

 

 

 

SonoStudy & Tutorial: Factors in testicular torsion diagnosis & treatment #FOAMed

Got to love the Canadians! This topic is also the first case that I posted in SonoSpot’s 1 year history, which reviews technique and an interesting case that baffled us yet becoming more clear with ultrasound (imagine that!). There have also been other case reports that I highlighted speaking about scrotal injuries. In this study, published in AJR, the authors set out to evaluate ultrasound accuracy, findings, and clinical predictors in pediatric testicular torsion. What factors correlate? Now, you could say that you dont need ultrasound and that physical exam alone will diagnose it, but interestingly, and not surprisingly, the physical exam isnt reliable and there have been other diagnoses made by ultrasound that helped rule in other causes of scrotal pain.

This study is a retrospective review, so take that into consideration when thinking about obstacles/limitations to the study, and the actual number of torsion cases was 35. But, it is interesting to note the factors they found with the torsion cases, particularly the ultrasound findings. Looks like color doppler is still good for something! See abstract below:

“OBJECTIVE. Testicular torsion is a common acute condition in boys requiring prompt accurate management. The objective of this article was to evaluate ultrasound accuracy, findings, and clinical predictors in testicular torsion in boys presenting to the Stollery pediatric emergency department with acute scrotal pain.

METHODS. Retrospective review of surgical and emergency department ultrasound records for boys from 1 month to 17 years old presenting with acute scrotal pain from 2008 to 2011 was performed. Clinical symptoms, ultrasound and surgical findings, and diagnoses were recorded. Surgical results and follow-up were used as the reference standard.

RESULTS. Of 342 patients who presented to the emergency department with acute scrotum, 35 had testicular torsion. Of 266 ultrasound examinations performed, 29 boys had torsion confirmed by surgery. The false-positive rate for ultrasound was 2.6%, and there were no false-negative findings. Mean times from presentation at the emergency department to ultrasound and surgery were 209.4 and 309.4 minutes, respectively. Of the torsed testicles, 69% were salvageable. Sensitivity, specificity, and diagnostic accuracy of ultrasound for testicular torsion were 100%, 97.9%, and 98.1%, respectively. Sonographic heterogeneity was seen in 80% of nonviable testes at surgery and 58% of patients with viable testes (p = 0.41).

Sudden-onset scrotal pain (88%), abnormal position (86%), and absent cremasteric reflex (91%) were most prevalent in torsion patients.

CONCLUSION. Color Doppler ultrasound is accurate and sensitive for diagnosis of torsion in the setting of acute scrotum. Despite heterogeneity on preoperative ultrasound, many testes were considered to be salvageable at surgery. The salvage rate of torsed testes was high.”

Among some other limitations, one limitation of this study is the number of torsion cases – I would have liked to have seen more – possibly a multi-site study is needed given the lack of high volume pediatric testicular torsion cases that come to the emergency department every year. Of course, there have been so many studies done that a meta-analysis can be written.

So, when you get that patient with acute scrotal pain, testicle in horizontal or abnormal lie, and an absent cremastreric reflex (and even after you have attempted to de-torse the testicle through the medial to lateral “opening a book” approach – right testicle counter clockwise, left testicle clockwise), place the patient’s leg in an open frog-leg position (you can use a towel under the scrotum to elevate and secure the scrotum in place if the patient tolerates it) and use your longer footprint linear probe. After examining the normal testicle in its transverse, longitudinal and coronal planes with and without color doppler to assess changes in echogenicity and arterial flow, examine the affected testicle the same way. Then, by using the longer footprint linear probe you can examine both testicles in the same view for adequate comparison ability.

Thanks to Dr. Turandot Saul for the images below:

An early ischemic testicle will be enlarged with no change in echogenicity, but a late ischemic testicle will be hypoechoic but may still have preserved structure: testicular torsion early

Also, a late torsed testicle will have abnormal echogenicity and structure: testicular torsion late

Normal testicle has normal echogenicity, normal color doppler flow within testicle:testicule normal flow

Testicle torsion will have absence of testicular flow and may get to the poibnt of hyperemia surrounding the testicle:

testicular late torsion extratestbloodflow   testiculartorsionnoflow

To read a medscape article on testicular torsion and ultrasound findings, go here.

SonoGuide has a great overview of the technique and images of testicular pathology – go here.

The Journal of Ultrasound in Medicine had a good review of the role of spectral doppler in early torsion, go here.

And, of course, Ultrasound Podcast has a great podcast on the how-to of Testicle Ultrasound part 1 and 2:

For another great pictorial review of testicular US and pathology, go here.

Sono-iBook: Intro to Bedside Ultrasound – great chapters/images/videos – Volume 1& 2 in iTunes! #FOAMed

LLLLLLLLet’s get ready to UltraSoooooooouuuuuuuuund!!!! It’s what we have all been waiting for! It’s finally here! Weighing at a meager zero pounds (since it’s on the iPAD, oh yeah!), another amazing product of Drs. Mike Mallin and Matt Dawson of ultrasoundpodcast fame, and authors including experts in bedside ultrasound from around the world (and little ole’ me too). I’d like to present the SECOND volume of the Introduction of Bedside Ultrasound ! And, as Mike and Matt say it best, “If you already own Volume 1….” (which include topics in basic ultrasound applications & more filled with visual image and video clip tutorials – unlike any other “text”book that you have ever owned!) “…..this is much better.  If you don’t yet own Volume 1….they’re equal…..get them both.” – Yes, trust me, you will not be disappointed. You can also get Volume 1 on inkling chapter by chapter purchasing ability where you can read it on your iPHONE too!)Take your iPAD to the bedside, place it on the ultrasound machine, or both to help guide your ultrasound education and that of others! Volume One pics:

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Volume Two involves topics on TEE (which is an up and coming application of bedside ultrasound in cardiac arrest), MSK, Right Heart, EMS, Medical Education, Gallbladder, more Nerve Blocks (that’s where I come in..heehee :), PIV, Soft Tissue, DVT, Appy, Peds, Diastology, and much more!  364 pages of interactive content, with HOURS of video demonstrations and tutorials. – doesn’t that make you drool!?! In volume two picture: …do you know what technique that is? you will…

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To hear them speak on it, and to get a taste of perfection, go here.

Screen Shot 2013-05-17 at 12.03.24 PM and Screen Shot 2013-05-17 at 12.03.28 PM

SonoStudy: Emergency docs detect small bowel obstruction by US – as good as radiologists #FOAMed

In a recent article in the European Journal of Emergency medicine, the authors showed that emergency physicians are just as good as radiologists in detecting small bowel obstruction by bedside US. Now, it’s not hard to do, nor is it hard to see it. First off, use your abdominal low frequency probe, and evaluate the abdomen in different quadrants. Normally, the bowel appears as a single circular hypoechoic layer (muscle layer) surrounding hyperechoic bowel contents of gas and food particles. The normal thickness of this layer during the contraction stage of peristalsis is 2-3 mm. The hypoechoic normal wall becomes thinner during peristalsis when the bowel is relaxed.

In small bowel obstruction- looking for dilated fluid filled loops of bowel with hyperechoic (bright) spots within it that may have back and forth peristalsis and a thicker intestinal wall (decreased persitalsis is a late finding) – color doppler gives info about blood flow in the walls of the intestine – and you may even see a transition point. Timothy Jang and team studied ultrasound compared to Xray for SBO and found that ultrasound is better, like WAYYYY better (higher sensitivity and specificity) – hmmm, interesting – Some things to consider: fluid-filled loops (good for US), but air-filled loops may not be so good. Ileus and SBO may appear similarly, so consider thinking of causes of ileus as well (gallstone ileus, etc), and a thickened wall may just be colitis, but that along with dilated loops and back and forth persitalsis with a transition point seen – more likely SBO.

This is what it would look like (and there are more clips to view – thanks to SonoCloud)

The abstract of the study follows:

“Objective: Our objective was to study the accuracy of emergency medicine [(EM) bedside ultrasonography (BUS)] and radiology residents performed ultrasonography (RUS) in patients with suspected mechanical small bowel obstruction (SBO).

Methods: After a 6-h training program, from January to June 2009, four EM residents used BUS to prospectively evaluate the patients presenting to the emergency department with suspected SBO. Then, patients underwent RUS. Outcome was determined by surgical findings if they were operated upon or self-reported the condition upon telephone follow-up at 1-month. BUS and RUS results were compared with χ2 testing.

Results: Of the 174 enrolled patients, 90 patients were BUS-positive. Of these, surgical findings agreed with the BUS findings in 84 patients. In 78 cases, BUS was negative, and 76 of these patients had benign clinical courses. Six patients were excluded from the study. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio for BUS were 97.7, 92.7, 93.3, 97.4, and 13.4%, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value for RUS were 88.4, 100, 100, and 89.1%, respectively. The diagnostic accuracy of BUS and RUS were not statistically different from each other (κ=0.81). The presence of dilated small bowel loops (>25 mm in jejunum or >15 mm in ileum) was the most sensitive (94%) and specific (94%) sonographic finding for SBO.

Conclusion: Abdominal sonography for the diagnosis of SBO is a new application of BUS in the emergency department. EM residents can diagnose SBO using BUS with a high-degree of accuracy, comparable with that of radiology residents.”

To read the UltrasoundPodcast guys speak on the subject, click here>

To see them do it, see below:

SonoLectures: Free lecture on Ultrasound in the Critically Ill -by Dr. Cliff Rice (& other free lectures)

Got an email from ACEP and thought it was too good not to share: Hear Dr. Cliff Rice, an ultrasound extraordinaire and emergency physician speak about bedside ultrasound and its use in critical care medicine. At the end of this post are even more lectures that are free. As you will hear, he states “Think about how you would use it in some of our sickest patients that come to the emergency department….. where the differential diagnosis is quite broad, and the treatment for shock might be detrimental if we are wrong.”

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As ACEP states in the email: “Practicing emergency physicians need to be able to utilize ultrasound effectively in the evaluation of the critically ill patient. In this free audio recording from the 2012 ACEP Scientific Assembly, Dr. Rice highlights the use of ultrasound to perform a FAST scan, to dynamically monitor and measure the IVC in the setting of hypovolemic shock, and to detect pericardial effusion and perform ultrasound guided pericardiocentesis [in 45 minutes]. This [lecture] explains where you should start scanning, narrows your differential and guides your resuscitation.”

Other free lectures for your viewing/hearing pleasure on bedside ultrasound:

Dr. Chris Fox’s comprehensive emergency ultrasound lectures in iTunes

Dr. Phil Perera comprehensive emergency ultrasound lectures on Sound-Bytes

AIUM UltrasoundFirst lecture series on various ultrasound topics

UltrasoundPodcast with a variety of lectures on bedside ultrasound

UltrasoundVIllage website on a variety of ultrasound topics

Vanderbilt’s excellent lectures library on bedside ultrasound

SonoCase from EPMonthly: 19 yr old with food poisoning? hmm….by B. Pregerson and T. Wu

Merry Christmas everyone! For your reading pleasure this week, Id thought we would discuss a case whose topic is near and dear to my heart. In the most recent issue of EPMonthly, there is a great case and interesting “internal” discussion made quite humorously public by Drs. Pregerson and T. Wu of a young healthy male with right lower quadrant abdominal pain after eating at a “Roach Coach”…. which just so happen to have the best breakfast burritos, but I digress… The case discussion involves how the history and physical may help, how labs may (or may not) help and how an ultrasound can be of use to make you and your surgical colleagues feel better in taking the patient to the OR. There was a recent post on SonoSpot about ultrasound in appendicitis sharing data from a study about the CT findings when US “equivocal” cases arise.  When the ultrasound is positive – how great is that?! Quite a few studies recently on the topic and some of the more recent ones can be found here.

The case is followed by an extensive (and great) discussion of the technique, pearls and pitfalls of ultrasound in evaluating the appendix – because we all know there are quite a few. As far as the sensitivity ad specificity go, they state it best:

“Sensitivity & Specificity: Both the sensitivity & specificity of ultrasound for appendicitis are less than that of CT. In pediatrics the values are about 88% and 94% respectively, and in adults about 83% and 93%. (These numbers may vary depending on the experience of the ultrasonographer.) There are studies from Europe and Israel where they have used the “ultrasound first” approach for many, many years that show even better test characteristics. These values are actually not that bad when compared to CT scan whose sensitivity and specificity are around 94% and 95% respectively. Remember, however, that the performance characteristics for ultrasound can be significantly worse in overweight patients or those with overlying bowel gas. In addition, if the appendix is retrocecal or is lying in a difficult anatomical plane, the study will be more challenging.  Unfortunately, you may still have to do a CT scan if your ultrasound is non-diagnostic and your clinical suspicion is moderate to high, but the strategy of ultrasound first would likely decrease CTs by about 50%.”

And in kids…”You should be aware of the most recent recommendation of the American College of Radiology from the “Choosing Wisely” campaign, which states, “Don’t do computed tomography (CT) for the evaluation of suspected appendicitis in children until after ultrasound has been considered as an option.” Although CT is accurate in the evaluation of suspected appendicitis in the pediatric population, ultrasound is nearly as good in experienced hands. Since ultrasound will reduce radiation exposure, ultrasound is the preferred initial consideration for imaging examination in children. If the results of the ultrasound exam are equivocal, it may be followed by CT. This approach is cost-effective, reduces potential radiation risks and has excellent accuracy, with reported sensitivity and specificity of 94 percent.”

To diagnose appendicitis: look for a noncompressible a-peristaltic structure that attaches to the cecum that is larger than 7mm in diameter.

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A great tutorial of ultrasound for the appendix can be found here by the UltrasoundPodcast guys:

SonoStudy and Tutorial: EPSS vs fractional shortening for LV function – is EPSS good enough?

In a recent issue of the Journal of Ultrasound through AIUM, Weekes et al. (and Kendall et al in AM J EM) talk about a hot topic that emergency and critical care physicians hold dear to them – the EPSS , or E-point septal separation – the minimal distance between the anterior mitral valve leaflet and the interventricular septum in the parasternal long view of the cardiac echo during diastole using M-Mode. Now, EPSS is not a part of point of care echo right now (i know, phew!), but there are conversations about whether it should be. The reason is because it is thought that EPSS is a good tool for LV function delineation, possibly better than simple visualization, despite knowing the risks of underestimating ejection fraction due to endocardial output limitations (see below). …Yeah, I know, that’s a lot of words and it took me a year to really understand what the above meant. So, let’s talk about it…especially as it is included in the updated RUSH protocol by Seif, Perera, et al.

EPSS by echo has even been compared to cardiac MRI for LV function recently. And, Dr. Mike Stone and friends did a study last year with regard to EPSS compared to qualitative LV function, stating: “Dyspneic patients with acute decompensated heart failure (ADHF) often present to the emergency department (ED), and emergency physicians (EPs) must act quickly and accurately to evaluate and diagnose patients with ADHF. Traditionally, key components of the patient’s history, physical examination, electrocardiography, and chest radiography are used to diagnose ADHF. However, no single test is highly accurate, and even with the incorporation of B-type natriuretic peptide levels, the diagnosis of ADHF in a dyspneic patient in the ED can be a challenge. Additional modalities that allow prompt and accurate diagnosis of ADHF would be of clinical utility, and estimation of left ventricle ejection fraction (LVEF) using point-of-care ultrasound has been the focus of prior research” showing that EPSS is a good tool compared to qualitative LVEF visualization. EM News folks also highlighted EPSS in a recent entry.

Now, lets talk a bit about the anatomy and physiology about this before we talk about the study. The mitral valve has an anterior leaflet and a posterior leaflet. You can see the mitral valve open and close in the parasternal long view of the heart. the below picture indicates the anterior leaflet:

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Using the Cardiovscular Institute’s diagrams, we can see the functioning of the mitral valve during systole and diastole in relation to the EKG, with every movement /peaks delineated with a letter  ….one of them being “e” (where E of EPSS comes from):

Screen shot 2012-12-14 at 10.46.50 AMScreen shot 2012-12-14 at 10.48.15 AM

…and in relation to the EKG on M-mode on the PSL view (aka motion mode – basically visualizing the motion of objects in time).

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EPSS of >7mm is thought to be an indication of poor LV function. Some use 1cm as the mark to increase their sensitivity for low ejection fraction. So, you can see that it should be a good indicator of LV function.

Fractional shortening (FS), however, is….(LVEDd-LVESd) / LVEDd expressed as a percentage. Placing the M-mode cursor across the LV just beyond the mitral valve leaflets, a tracing is shown whose measurements of the LV chamber diameter in both systole and diastole can illustrate FS, or LV contractility (not ejection fraction as it is not a volume measurement). Normal FS being 30-45%. For a complete description of these terms go here – a great overview by ICU Sonography –  and here – a simpler way to understand the measurements through the Stanford ICU website. The updated RUSH protocol, also explains this well, with images from their most recent publication below:

Hyperdynamic/hypercontractile: FS >45%

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Abnormal: hypocontractile LV: FS<30%

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So, the study was a prospective study, thankfully, and seemed to really want EPSS to be good for LV function, but it looks like it’s not as good as we think:

Abstract: “Objectives Rapid bedside assessment of left ventricular (LV) function can aid in the evaluation of the critically ill patient and guide clinical management. Our primary hypothesis was that mitral valve E-point septal separation measurements would correlate with contemporaneous fractional shortening measurements of LV systolic function when performed by emergency physicians. Our secondary hypothesis was that E-point septal separation as a continuous variable would predict fractional shortening using a linear regression model.

Methods We studied a prospective convenience sample of patients undergoing a sequence of LV systolic function measurements during a 3-month period at a suburban academic emergency department with a census of 114,000 patients. The sample included adult emergency department patients who were determined by the treating emergency physician to have 1 or more clinical indications for bedside LV systolic function assessment. Investigators performed bedside M-mode cardiac sonographic measurements of fractional shortening and E-point septal separation using the parasternal long-axis window. The sequence of LV systolic function measurements was randomized.

Results A total of 103 patients were enrolled. The Pearson correlation coefficient for E-point septal separation and fractional shortening measurements was –0.59 (P< .0001). Linear regression analysis performed for E-point septal separation with fractional shortening as the dependent variable yielded an R2 value of 0.35.

Conclusions E-point septal separation and fractional shortening measurements had a moderate negative correlation. E-point septal separation, when used as a continuous variable in a linear regression model, did not reliably predict fractional shortening.”

The limitations of EPSS as discussed in Stone’s paper:

Valvular diseases that restrict anterior mitral leaflet motion ( mitral stenosis, aortic insufficiency) – will exaggerate EPSS.

Asymmetric septal hypertrophy,

Severe left ventricular hypertrophy,

Discrete proximal septal thickening (sigmoid septum) can lead to small
estimates of EPSS.

Failure to obtain a true parasternal long-axis view may result in falsely elevated
EPSS measurements due to a tangential measurement from mitral valve leaflet to septal wall.

….At the end of the day, my opinion -> just visualizing the LV contractility, as long as you have a good PSL and PSS long view, and you’ve seen enough to know normal versus abnormal, is good enough for me!

SonoProcedures: Review of ultrasound-guided procedures, technique, and videos

In the most recent addition of Emergency Medicine Clinics of North America (yup, you’ll need to register to view), some big wigs in bedside ultrasound (Tirado, Teresa Wu, Resa Lewiss, Vicki Noble, Adam Sivitz) published an article reviewing the ultrasound – guided techniques (with images) of procedures where an ultrasound machine can make all the difference in decreasing complications, increasing patient satisfaction, and decreasing time of procedure. From pericardiocentesis, thoracentesis, abscess drainage to lumbar puncture, arthrocentesis, and foreign body removal, these physicians discuss it all. “Bedside ultrasound is an extremely valuable and rapidly accessible diagnostic and therapeutic modality in potentially life- and limb-threatening situations in the emergency department. In this report, the authors discuss the role of ultrasound in quick assessment of pathologic conditions and its use to aid in diagnostic and therapeutic interventions”

In the same issue, Drs. Tirado, Nagdev and others discuss ultrasound-guided venous central and peripheral venous access and nerve blocks (a topic near and dear to Arun Nagdev’s heart – given how many publications he has done on the topic – a true expert!). “Ultrasound has rapidly become an essential tool in the emergency department, specifically in procedural guidance. Its use has been demonstrated to improve the success rate of procedures, while decreasing complications. In this article, we explore some of these specific procedures involving needle guidance and structure localization with ultrasound.”

And, in the same issue, Drs. Lewis, Crapo, and Williams discuss more procedural guidance using bedside ultrasound for central venous access as well as a review of other procedures, like IO lines an arterial lines. “The venous and/or arterial vasculature may be accessed for fluid resuscitation, testing and monitoring, administration of blood product or medication, or procedural reasons, such as the implantation of cardiac pacemaker wires. Accessing the vascular system is a common and often critically important step in emergency patient care. This article reviews methods for peripheral, central venous, and arterial access and discusses adjunct skills for vascular access such as the use of ultrasound guidance, and other forms of vascular access such as intraosseus and umbilical cannulation, and peripheral venous cut-down. Mastery of these skills is critical for the emergency medicine provider.”

A great review of pericardiocentesis, thoracentesis, paracentesis, vascular access, foreign body localization, abscess drainage, and nerve blocks can be found on Sonoguide as well.

Here are some great videos on how-to perform the varying procedures:

Pericardiocentesis:

Thoracentesis:

Paracentesis:

Abscess drainage:

Central venous access: internal jugular

Central venous access – supraclavicular approach to the subclavian vein:

Ultrasound Podcast on the Subclavian and Supraclavicular venous access in only the way they know how.

Central venous access – axillary vein cannulation

Peripheral venous access:

A great video on US guided Peripheral IV can be found here, by HQMedEd

Lumbar puncture:

Foreign Body removal:

Femoral nerve block:

Axillary Nerve block:

Distal Sciatic nerve block:

Nerve blocks of all kinds can be found here on SonicNerve.

Other procedures:

US guided fracture reduction

 

SonoTutorial: Musculoskeletal Ultrasound of the Tendon – an AIUM Sound Judgement Series

In the recent entry of the Journal of Ultrasound in Medicine, Dr. Ken Lee (MSK radiology), discusses how ultrasound of the tendon can add to your clinical work up of a patient with pain in that area. it is the most common sports-related injury and we see it in the emergency department all.the.time.  In a prior post, we highlighted how Dr. Brita Zaia evaluated a patient with knee pain and tenderness who came to the ED for an arthrocentesis, showing the patellar tendon abnormality on her ultrasound image, making her diagnosis without the need of that invasive procedure (Published in WestJEM).

“Common tendon abnormalities include tendinopathy and tendon tears, which impose a substantial cost to society in the United States and abroad. According to the American Public Health Association, tendon disorders account for approximately $850 billion per year in health care costs and indirect lost wage expenditures.4 Accurate and timely diagnosis of musculoskeletal tendon injuries is critical to ensure proper treatment and thus minimize societal costs. Magnetic resonance imaging (MRI) has been the imaging standard for musculoskeletal injuries. However, MRI is costly and overused.5 Improvements in ultrasound technology have made sonography a rapidly growing imaging alternative and complementary tool to MRI for the diagnosis of common tendon injuries.6…..The most defining advantage of sonography over MRI is its real-time imaging capability, which allows for dynamic evaluation of the tendon using a variety of stress maneuvers.16,17 For example, in the neutral position, the long head of the biceps tendon may lie normally in the bicipital groove (Figure 3), only to dislocate medially once the arm, with elbow flexed, is externally rotated (Figure 4). In addition to tendon subluxation, other tendon abnormalities diagnosed dynamically include tendon snapping, friction between two structures such as in shoulder impingement,18 and increasing conspicuity of tendon tears while stressing the tendon or with sonopalpation.17 Real-time dynamic sonographic evaluation provides this unique diagnostic ability using controlled movements.”

Read more in this article to learn about what it means and what happens when the tendon goes from looking like this:

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..to looking like this:

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or like this….

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with plenty more examples of it, illustrating how awesome it is and why we should use bedside ultrasound to evaluate tendons more.