UMEM Educational Pearls - By Alexis Salerno

Title: Lung Ultrasound for CHF in the Prehospital Setting

Category: Ultrasound

Keywords: POCUS, Lung ultrasound, EMS (PubMed Search)

Posted: 12/2/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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Early treatment of congestive heart failure (CHF) exacerbations is associated with improved mortality rates and shorter hospital length of stay. Lung ultrasound is a valuable tool in diagnosing CHF exacerbations. Recently, several studies have explored the use of lung ultrasound in the prehospital settings to expedite diagnosis and treatment. 

A recent systematic review and meta-analysis evaluated the diagnostic accuracy and clinical impact of prehospital lung ultrasound. The authors found similar test characteristics to point-of-care ultrasound (POCUS) performed in the emergency department. 

The eight studies included in the analysis utilized varying lung ultrasound protocols, analyzing between 2 and 8 lung zones. Notably, only two studies involved paramedics performing the ultrasounds, yet no significant difference in diagnostic accuracy was observed. 

Further research is needed to evaluate the training requirements for prehospital providers and the broader impact of prehospital lung ultrasound on treatment strategies and patient outcomes.

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Title: POCUS for Achilles Tendon

Category: Ultrasound

Keywords: POCUS; MSK; Achilles tendon (PubMed Search)

Posted: 11/18/2024 by Alexis Salerno, MD
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Achilles tendon injuries are commonly encountered in the emergency department. While MRIs are often unavailable, POCUS offers a quick and effective alternative for evaluating such injuries. In one review, the sensitivity of ultrasound for detecting complete Achilles tendon ruptures was 94.8%.

For the POCUS evaluation of the Achilles tendon:

- Place the patient in a prone position with their foot relaxed.

-Begin distally at the tendon’s insertion on the calcaneus and scan proximally, keeping the probe marker oriented toward the patient’s head.

-Next, obtain a transverse view by rotating the probe marker toward the patient’s right side.

-You can even do a sonographic Thompson’s Test!

Findings:

Complete Rupture: Displays as a full disruption of the tendon fibers.

Partial Tear: Shows intact tendon tissue with surrounding edema.

Tendinitis: Appears as a thickened tendon with increased vascularity on color Doppler imaging. 

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If significant orbital edema prevents visual assessment of the pupillary light reflex, ocular ultrasound can be a useful alternative. 

  1. Set up for a standard ocular POCUS exam. 
  2. Place the linear probe transversely over the lower portion of the eye and tilt it upward to visualize the iris and pupil. 
  3. Shine a light over the affected eye to observe the direct light reflex. 
  4. For consensual reflex, shine the light over the opposite eye.

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Title: Point-of-Care Ultrasound (POCUS) of the Stomach: An Emerging Application

Category: Ultrasound

Keywords: POCUS; Aspiration Risk; Intubation; Gastric Ultrasound (PubMed Search)

Posted: 10/20/2024 by Alexis Salerno, MD (Updated: 10/21/2024)
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Recent guidelines from anesthesia societies and recent literature emphasize the use of gastric POCUS for aspiration risk assessment. While the role of gastric POCUS in the emergency department is still being explored, one recent article highlighted its use in assessing patients with upper gastrointestinal bleeding (UGIB).

Performing Gastric POCUS:

Patient Position: Place the patient in the right lateral decubitus position, if unable can perform in supine position.

Probe Selection & Placement: Use a curvilinear probe in the sagittal position at the level of the subxiphoid process, similar to the longitudinal view of the proximal abdominal aorta.

Scanning Technique: Fan the probe left to right to assess the gastric antrum.

Interpretation of Gastric Antrum:

Empty Antrum: Appears as a "bull's eye" or flat, with no visible liquid inside.

Full Stomach: Distended antrum with floating contents. 

Intermediate: Shows a small amount of anechoic fluid without floating contents.

Quantitative Evaluation:

It is also possible to perform a quantitative evaluation of the gastric antrum to further assess stomach contents, this may be more useful in patients with intermediate gastric antrum.

For more details, refer to the articles and videos cited.

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Title: What’s the talk about the Lipliner Sign?

Category: Ultrasound

Keywords: POCUS; FAST exam (PubMed Search)

Posted: 9/30/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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The Lipliner Sign is causing a lot of buzz within the ultrasound community, particularly concerning its implications for focused assessment with sonography for trauma (FAST) exams. This artifact arises from postprocessing techniques that enhance organ visualization but can inadvertently create a hypoechoic line that resembles free fluid leading to false positive exams. 

Key points to note: 

Nature of the Artifact: The Lipliner Sign manifests as a linear, hypoechoic outline around an organ, misleading clinicians into thinking there's free fluid present. 

Differentiation: As mentioned in this case report, free fluid typically appears wedge-shaped and tapers as it moves into dependent areas, while the Lipliner Sign is more linear and closely follows the organ's contour. 

Manufacturer Variability: This artifact can be observed across different ultrasound machine manufacturers. 

Clinical Implications: Misinterpretation of the Lipliner Sign could lead to unnecessary interventions or misdiagnoses in trauma settings, underscoring the importance of thorough training and awareness of potential artifacts.

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Title: Ultrasound for Glenohumeral Joint Evaluation

Category: Ultrasound

Keywords: musculoskeletal, POCUS, joint arthrocentesis, shoulder dislocation, joint injection (PubMed Search)

Posted: 8/19/2024 by Alexis Salerno, MD
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To obtain a posterior shoulder view: Have the patient sit up with the back of the bed down. Position the curvilinear probe in the posterior aspect of the shoulder with the probe parallel to the patient bed, at the level just below the scapular spine and the marker towards the patient's left. You can have the patient rotate their arm to help you visualize the movement of the humeral head.

In the normal anatomy, the humeral head should be at the level of the glenoid (this is a patient's left shoulder):

Locate the glenohumeral joint space.  You can evaluate the GH joint for effusion, perform joint arthrocentesis/injection and look for signs of shoulder dislocation. 

If you are evaluating for signs of a dislocation:

Posterior dislocation: the humeral head will be more SUPERFICIAL in the image than the scapular spine

Anterior dislocation: the humeral head will be DEEPER in the image than the scapular spine.



Title: Hemopericardium or Just a Fat Pad?

Category: Ultrasound

Keywords: POCUS, Trauma, Cardiac Tamponade, Pericardial Effusion, FAST exam (PubMed Search)

Posted: 8/5/2024 by Alexis Salerno, MD
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In a critically ill trauma patient, the FAST exam is used to evaluate for potential internal injuries. Specifically, the subxiphoid view of the FAST exam helps assess for signs of pericardial tamponade. However, distinguishing between a pericardial effusion and an epicardial fat pad can be challenging. 

One study indicated that the sensitivity of EPs in differentiating between effusion and fat pad was 73%, with a specificity of 44% when reviewing difficult patient video clips. 

Here are some tips to help you distinguish between effusion and fat pad: 

Change your view: Use the parasternal long axis view, which is more sensitive for effusion. Fat pads are usually anteriorly, and effusions tend to accumulate posteriorly in a supine patient. 

Screen for other signs of tamponade: Adjust your subxiphoid view to visualize the IVC entering the right atrium, allowing better visualization of the right side of the heart. 

Movement: Fat tends to move synchronously with the heart, whereas hemopericardium moves independently. 

Echogenicity: Fat typically appears brighter on ultrasound, while blood tends to be less echogenic.  

For further learning, refer to the supplemental Material from the referenced articles. 

Blood or Fat? Differentiating Hemopericardium versus Epicardial Fat Using Focused Cardiac Ultrasound - PMC (nih.gov)

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POCUS for DVT is a tricky examination. 

  • Compression should be performed in transverse orientation.
  • A negative exam means that the vein should completely collapse with the same pressure to compress the neighboring artery. 
  • Thrombus may not always be visualized.

Exam of positive study on transverse:

Longitudinal Image showing clot: 



Title: IVC Pitfalls

Category: Ultrasound

Keywords: POCUS, fluid resuscitation, Inferior Vena Cava (PubMed Search)

Posted: 7/15/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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Many may look at the Inferior Vena Cava (IVC) to get a sense of a patient's “fluid responsiveness.” However, there are many pitfalls to using the IVC. An article by Via et al outlines these pitfalls and is an interesting read! 

To summarize, IVC can be affected by:

  1. Ventilator Settings such as high PEEP
  2. Patient's inspiratory efforts such as significant respiratory efforts
  3. Asthma/COPD exacerbations
  4. Cardiac Conditions impeding venous return such as tamponade or RV dysfunction
  5. Increased abdominal pressure such as intra-abdominal hypertension
  6. Other factors such as asking the patient to take a breath in, poor measurements, ivc compression by masses or ECMO cannulae

Bottom Line: Think twice before using IVC to evaluate for fluid responsiveness.

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Title: POCUS for SBO

Category: Ultrasound

Keywords: POCUS, GI, SBO (PubMed Search)

Posted: 7/8/2024 by Alexis Salerno, MD
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POCUS has been shown to have a 92.4% sensitive (95% CI 89.0% to 94.7%) and 96.6% specific for identifying SBO. 

Some characteristics of SBO include:

-dilated fluid filled bowel  

-contents of bowel moving to and fro like a washer machine 

-wall thickening and ability to see plicae circulares 

- in high grade obstruction you may also notice intraperitoneal fluid near the dilated bowel. 

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Title: FAST exam Pitfalls

Category: Ultrasound

Keywords: POCUS; FAST exam; Trauma (PubMed Search)

Posted: 6/17/2024 by Alexis Salerno, MD
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Although the FAST exam can be helpful in expediting care of patients with intraabdominal injuries, there are a few pitfalls. 

Pitfalls:

1. The FAST exam has a wide sensitivity which depends on sonographer skill and the patient's body habitus. It is best used as a “Rule In NOT Rule Out” exam. 

2. The FAST exam is not good for identifying bowel injury or retroperitoneal bleeding and may not be able to pick up low volume hemoperitoneum. 

3. The FAST exam is not able to identify the type of fluid e.g. ascites vs blood. 

Some Tips for Performing the FAST exam:

1.Go slow, fan through the view completely. In the RUQ view make sure you are evaluating the liver tip.

2. Place the patient in slight Trendelenburg. 

3. If you have clinical concern for injury, don't stop at a negative FAST.

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Title: Water Baths for Fingers

Category: Administration

Keywords: POCUS, musculoskeletal, fingers, water baths (PubMed Search)

Posted: 6/3/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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Do you have a patient with a finger injury or infection, or possibly a retained foreign body?

Try placing the hand in a water bath and use a linear ultrasound probe for evaluation. If there is an open wound, use a sterile ultrasound probe cover.

With ultrasound guidance, you can observe dynamic finger movements and identify areas that may require abscess drainage.



Title: POCUS for Pleural Effusion

Category: Ultrasound

Keywords: Pleural Effusion; POCUS (PubMed Search)

Posted: 4/22/2024 by Alexis Salerno, MD (Updated: 4/29/2024)
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How do you look for signs of a pleural effusion with ultrasound?

Place your ultrasound probe in the mid axillary line with the probe marker placed towards the patient's head. 

Find the movement of the diaphragm and scan just above the diaphragm.

In normal lung, air scatters the ultrasound signal, and you are not able to see structures above the diaphragm.

With a pleural effusion, you can see:

  • anechoic fluid above the diaphragm
  • consolidated lung moving like a jelly fish
  • the spine above the diaphragm



Title: US Guided LP Site Marking

Category: Ultrasound

Keywords: POCUS; Lumbar Puncture; Neurology (PubMed Search)

Posted: 4/15/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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Simple tool to help improve your next lumbar puncture: Use ultrasound for site marking.

This can be done in a patient sitting up or laying on their side.

-First start with the probe marker midline towards the patient's head and use the ultrasound to identify the L4/L5 and L3/L4 space.

-Use a surgical pen away from the gel to mark midline on both sides of the probe, using the midline marker on the ultrasound probe. You can use m mode to help you identify the middle of the image when using a curvilinear probe. 

-Then rotate the probe towards the patient's left and use the ultrasound to identify the midline point (spinous process)

-Use a surgical pen away from the gel to mark midline on both sides of the probe, using the midline marker on the ultrasound probe.

-Clean off the gel, connect the skin markings and use a 3 cc syringe to mark the center of the crosshair. 

-Sterilize and start your LP!



Title: Ultrasound Artifacts: The April Fool's of Ultrasound

Category: Ultrasound

Keywords: POCUS; Ultrasound Artifacts (PubMed Search)

Posted: 4/1/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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Ultrasound artifacts can sometimes be helpful, but sometimes they can be misleading. 

For example:

1)Does this patient have a gallstone?

No, this is edge artifact! This is due to the ultrasound signals refracting off the side of the gallbladder wall.

  1. Does this patient have sludge?

No, this is side lobe artifact! This is due to a bright reflector outside of the central beam of the ultrasound signal that the machine mistakenly places with in the center of the beam. Side lobe artifact can occur near fluid filled masses such as the gallbladder and bladder. 

  1. Is there tissue above the liver?

No, this is mirror artifact!! This is due to ultrasound signals bouncing off a highly reflective surface such as the diaphragm.  The ultrasound machine misinterprets the time delay from the reflected ultrasound signal as a structure deeper in the image.



What happens if you have a patient who steps on a nail? How can you make this procedure easier for you and the patient? 

– Use a Posterior Tibial Nerve Block! !

To Perform This Procedure:

  • Have the patient lay on a stretcher and externally rotate their hip and have their knee flexed.
  • Clean the area  
  • Use a linear probe with a sterile probe cover on
  • Place the probe with the marker towards the patient’s right, just above the medial malleolus and positioned posteriorly.
  • Identify the posterior tibial nerve next to the posterior tibial artery and center the probe on the nerve
  • Use a 22–30-gauge needle in an out of plane technique, slowly inject about 5 cc of anesthetic, making sure you are just above the nerve and not in the artery.

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Title: POCUS for hydronephrosis

Category: Ultrasound

Keywords: POCUS; Renal Colic; Flank Pain; Hydronephrosis (PubMed Search)

Posted: 2/5/2024 by Alexis Salerno, MD
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Ultrasound is the first line diagnostic tool to evaluate younger patients who present to the ED with flank pain. 

Most of the time on ultrasound, you will not see the actual kidney stone. More often, you will see associated signs such as hydronephrosis.

In a patient with hydronephrosis, the normally hyperechoic renal pelvis will become anechoic. With increased severity of the hydronephrosis, you can have complete distortion of the kidney. 

You can tell the difference between hydronephrosis and a renal vein by placing color doppler over the image. Hydronephrosis will not have flow. 

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Title: POCUS for Ankle Effusion

Category: Ultrasound

Keywords: POCUS, musculoskeletal, ankle, arthrocentesis (PubMed Search)

Posted: 1/29/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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Many patients present to the emergency department for ankle swelling. On way to identify signs of intra-articular swelling is to use POCUS. To perform this, place the linear probe at the tibio-talar junction with the probe marker placed towards the patient’s head. An effusion is identified as anechoic fluid in-between the tibia and talus bone.  

POCUS has been shown to improve first-pass success and overall success as compared to a landmark based approach for medium-sized joints. When performing an ankle arthrocentesis with POCUS, care should be taken to avoid blood vessels and tendons.

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Title: Ultrasound Signs of Cardiac Tamponade

Category: Ultrasound

Keywords: POCUS; Cardiac Tamponade; Cardiology; Critical Care (PubMed Search)

Posted: 1/15/2024 by Alexis Salerno, MD (Updated: 12/9/2024)
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What are the signs of Cardiac Tamponade on ultrasound? 

Think of them as a pyramid with clinical importance decreasing as you rise to the top of the pyramid.  

  • To have tamponade you need a pericardial effusion. 

  • The most specific sign of tamponade is RV collapse in diastole.  

  • The earliest and most sensitive sign is RA collapse over 1/3 of the cardiac cycle from late diastole into systole, which is why we say RA collapse during systole. 

  • IVC dilation also occurs but is not sensitive. 

  • Placing the pulse wave Doppler over the mitral valve and evaluating the change with respirations is an advanced technique. It’s positive if you have 25% change. 

Don’t know if you are in systole or diastole? Connect your telemetry leads to the ultrasound machine. Don't have leads? Then you can also cine scroll on a subxiphoid view or parasternal view to look at when the valves are open and closed, then compare to the cardiac wall positioning.

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Title: How to Perform a Transvaginal Ultrasound for OB

Category: Ultrasound

Keywords: Obstetrics; POCUS; Transvaginal Ultrasound (PubMed Search)

Posted: 12/18/2023 by Alexis Salerno, MD
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By performing a Point-of-Care Transvaginal Ultrasound (TVUS), we can decrease length of stay for patients with early pregnancy. Moreover, if an ectopic pregnancy is identified, we can decrease time to the OR for these patients. 

Begin by discussing the exam with the patient and ensuring they have emptied their bladder.  Apply a probe cover and add sterile lubricant to the outside of the probe tip. You can save time by performing a TVUS immediately after the pelvic speculum exam for swab collection.

  • Obtain a Sagittal View of the Uterus:

Gently introduce the transducer with the marker upward, directed towards the ceiling. As you slowly advance, the uterus will be visualized in a sagittal orientation. Fan through the uterus by moving the probe handle left and right.

Image From: doi: 10.1016/j.emc.2022.12.006.

  • Obtain a Coronal View of the Uterus:

Rotate the transducer so that the marker is directed towards the patient's right side. Fan through the uterus by lifting the probe handle up and down. 

Image From: doi: 10.1016/j.emc.2022.12.006.

  • Perform Measurements:

If a gestational sac is found, you should measure the gestational age and if present, fetal heart rate. 

  • Evaluate the Adnexa:

Tilt the transducer towards the patient's left or right side to visualize the adnexa. The adnexa will be located medially to the iliac vessels. 

  • End the Exam:

Remove the transducer and follow your department protocol for high level disinfection.

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