UCSD Ultrasound, Author at UCSD Ultrasound

December 16, 2017July 22, 2020

Case # 11: Look and You Will Find

A 32 year old healthy female with no past medical history presents to the emergency department with left sided flank pain x 2 days.

Vitals: T 98.6 HR 72 BP 126/82 RR 12 O2 98% on RA

A bedside ultrasound of the left kidney is performed, what is the next best step in management?

Answer and Learning Points

Answer

The ultrasound image demonstrates a simple cyst located in the cortex of the kidney. The cyst can be described as anechoic, homogenous, with thin and smooth walls, and would be a type I lesion according to the Bosniak classification system (image below). There is no evidence to suggest obstructing hydronephrosis. The Bosniak classification for renal cysts was developed in the 1980s as an attempt to standardize the description and management of complex renal lesions. Based on classification of the renal lesion, the likelihood of malignancy can also be predicted. While the Bosniak classification was initially described and validated with CT imaging, newer data suggests that ultrasound may be sufficient to follow renal cysts that are minimally complex (Bosniak I & II).

Learning Points

- Given the bedside ultrasound demonstrates a Bosniak I lesion in the left kidney, the patient can be reassured that this finding is very unlikely to be malignant and she can be referred to a primary care provider for follow up in several weeks for formal outpatient renal ultrasound.
- Incidental findings are frequently found on point of care ultrasound and while most of them are benign it is of utmost importance to ensure proper follow up when identified. Specifically with renal cysts, this is a common occurrence and most can be followed with renal ultrasound as long as they are simple (Bosniak I or II).
- One pitfall to be aware of is that renal cysts can be mistaken for hydronephrosis and lead to unnecessary imaging and work up (especially in patients presenting with acute flank pain). Therefore it is critical to note the differences between a simple renal cyst and hydronephrosis. As seen in the comparison above renal cysts tend to (but not always) be located in the renal cortex and are both spherical and very well circumscribed. On the other hand, hydronephrosis is centrally located, and tends to branch outwards like a tree. If there is uncertainty, I recommend performing evaluation in both transverse and longitudinal planes to fully characterize your finding. The opposite kidney in the patient can also be used for comparison.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Muglia VF, Westphalen AC. (2014) Bosniak classification for complex renal cysts: history and critical analysis. Radiol Bras 47(6): 368–373.

2. McGuire BB, Fitzpatrick JM. (2010) The diagnosis and management of complex renal cysts. Curr Opin Urol 20:349–354.

3. Case courtesy of Dr Matt Skalski, Radiopaedia.org. From the case rID: 20989

December 7, 2017July 22, 2020

How To: DIY Ultrasound Guided Peripheral IV Phantom

Introduction

Ultrasound-guided venous access has become a core skill for both emergency medicine providers, and nursing staff, to help facilitate difficult access. While clinical experience is critical to learning this technique, phantoms are also a necessary component, specifically with regards to developing both fine-motor skills and spatial orientation. In this post, we provide a step-by-step guide to creating a high-quality, affordable, phantom that can be used for educational purposes at large conferences or for small group training sessions.

1. The Set Up

The Mold: water, metamucil, gelatin, citric acid, blue food coloring

The Veins: animal balloons, red food coloring

The Container: supply case ( 5.08 x 5.25 x 1.9 )

The Tools: sharpie, scissors, syringe, sharp knife or razor blade, large whisk (not shown)

2. Create your Container

We chose the above container because it only requires 500 ml of gelatin mixture, it is plastic (which allows us to cut into it), and it has a lid which allows for easy transport and keeps the phantom fresh.

What you will be doing is creating small slits in the sides of the container to allow for the vessels to "float" and avoid having to pour gelatin in two steps which is both time consuming and messy.

2a. Measure out vessel depth and location

I like to place the vessels 1.5 cm below the surface of the gelatin mold. Using the thick plastic line near the opening of the box, measure 1.5 cm down from here. Measure 4 cm from each side of the box and connect everything with lines. The areas that cross will be where your vessels will go. Repeat this process on opposite side.

2b. Puncture four small slits in container

Now it's time to make small cuts in the plastic container which will allow the vessels to "float." I sit by the stove when doing this and turn on vent above to prevent significant inhalation of burning plastic fumes. Hold the tip of sharp knife or razor knife directly in flame until it turns red. Then quickly push knife into plastic at each line intersection, making approximately a 7-8 mm slit. You may have to re-heat knife between punctures.

Your container is now ready to be used, onto creation of your vessels.

2. Create your Vessels

The red food coloring adds an extra element to your phantom by making the "flash" in the angio-catheter chamber visible.

Fill your syringe with colored water and inject into balloon until it is plump. Next, make sure to get all the air out of the balloon that may have become trapped by holding the balloon vertical, allowing the air to rise to the top, and then tying this off. Continue to tie off the ends of the balloon and trim down with scissors until the vessel is just longer than the width of your container.

Make sure to leave around 1 cm of balloon on each side of your knots as you will need this to pull the vessels through the slits in the container.

3. Cannulate your Container

Take each balloon vessel and thread the ends through the slits in your container. Note as shown in the image that the knot will get caught up on the slit. I use the end of my scissors to pry open the slit slightly, allowing the knot to be pulled through with a little bit of force.

Once the knot is through, pull the balloon vessel out about 1 cm. This will allow the container to "auto-seal." so you do not have to worry about leaking when pouring in the gelatin mold.

This is the hardest step in constructing your phantom so do not be dissuaded if it takes you a few tries.

4. Make your Gelatin Mold

Now it's time to make your gelatin mold. Here are the amounts required for a 500 ml gelatin mold. You can multiply these amounts as needed if making multiple models at a time:

Water: 500 ml

Gelatin: 40 grams (~3.5 Tbsp)

Metamucil: 20 grams (~1.75 Tbsp)

Citric Acid: 1 Tbsp

Blue Food Coloring: 1 tsp

4a. Combine ingredients

Heat up the water in a large pot until it just begins to boil. At this point turn down heat so that water stays warm but is not bubbling. Too much heat will cause the mixture to froth and overflow.

Now add your ingredients, I do the gelatin first as this is the most difficult. It is critical to whisk the water the entire time while adding the gelatin slowly. If you dump the gelatin in all at once, it will form large clumps and ruin your phantom. I would also follow this same technique when adding the other ingredients.

Once all ingredients have been well combined and your mixture has thickened you are ready to pour your gelatin mold into your container.

4b. Pour the mold

Pour gelatin mold into your container, up to the thick plastic line. Allow the mold to cool for 10-15 minutes, then close lid and place in the fridge overnight to set.

The next day your mold will be ready to use!

5. Use your Mold

The mold is probably good for ~ 50-100 IV insertion attempts and can be used at multiple training sessions, though I probably would not keep it for more than 2 weeks. Here are a few other tips:

- The gelatin mold should be chilled until just prior to use to keep it firm; clean surface with water after use, pat completely dry, and store back in fridge to increase longevity.

- To optimize movement of probe along the surface of gelatin mold, be sure to apply a generous quantity to the surface.

- If you notice the balloons appear flat after multiple cannulations, you can refill by directly accessing them through the gelatin under ultrasound guidance and injecting slowly until they appear plump again (do not over pressurize or you may damage the phantom or cause a leak).

Questions?

Leave a comment or email us at ucsdultrasound@gmail.com

December 1, 2017July 22, 2020

Review of Lawsuits Related to Point of Care Emergency Ultrasound Applications

Background

Point-of-care (POC) ultrasound has become heavily integrated into clinical practice in emergency departments (ED). Ultrasound training is now standard in emergency medicine (EM) residency programs and most emergency physicians are able to independently perform and interpret bedside ultrasounds exams. With the rise in use of POC ultrasound by emergency physicians, there is an accompanying theoretical increase in malpractice risk. Malpractice risk can potentially arise from failure to perform an adequate study, failure to interpret findings accurately, or misdiagnosis. This increased liability has prompted some emergency physicians to avoid POC ultrasound in their own practice to decrease their personal risk or transfer risk to consulting services, such as radiology. However, the opposite argument could also be made that failure to incorporate ultrasound into one’s emergency medicine practice can leave clinicians susceptible to legal action as well. This study aims to build on the work of Blavais et al, which revealed that from 1987-2007 there was only one identifiable malpractice lawsuit associated with POC ultrasound. Given the increased use of POC ultrasound since the prior study, this article aims to further characterize the nature of malpractice lawsuits associated with POC ultrasound in more recent years.

Review of lawsuits related to POC emergency ultrasound applications

Clinical Question

With the increased use and scope of practice of POC ultrasound in EM, is there an associated increased legal risk to emergency physicians performing POC ultrasound?

Methods & Study Design

Design
- Retrospective review of Westlaw database for reported decisions in state and federal malpractice cases involving POC ultrasound
  - Westlaw database include state and federal case law and statutes, and public records
Population
- Published case law in the US from Jan 2008 – Dec 2012 in the Westlaw database
Inclusion criteria
- Cases were included if:
  - Physician was accused of misconduct
  - Patient encounter was in ED
  - Interpretation or failure to perform ultrasound was discussed to any degree
  - Ultrasound application was within ACEP ultrasound core applications (trauma, intrauterine pregnancy, AAA, cardiac, biliary, DVT, urinary tract, soft tissue/MSK, thoracic, ocular, procedure)
  - Ultrasound exam performed or ordered through a radiology department was within scope of ACEP core emergency ultrasound applications
Exclusion criteria
- There were no specific exclusion criteria. However, cases settled out of court, cases with unreported decisions, and cases not publically available (private negotiations, arbitration, sealed records, etc) were not available for analysis through the Westlaw database.
Intervention
- Westlaw database was reviewed for published case law (federal and state) in the US from Jan 2008 – Dec 2012
- Search terms included “ultrasound”, “sonography”, “emergency”, “physician”, “doctor”
- Emergency physicians with emergency ultrasound fellowship training reviewed case records that were identified via search. Specific case information was collected. Any discrepancies were discussed between the two reviewers to reach a consensus.
Outcomes
- - The follow case information was collected:
    - Basic clinical narrative of case
    - Exam type involved
    - Department that performed exam
    - Broad category of type of allegation (i.e. misdiagnosis, failure to interpret, failure to perform, failure to perform in timely manner)

Results

- 120 records matched initial search criteria; 7 of these matched inclusion criteria
  - 2 out of 7 were reviewed and found to be outside the scope of ACEP core ultrasound applications
- 5 identified malpractice cases relating to POC ultrasound in the ED
  - No cases resulted from misdiagnosis with POC ultrasound or failure to interpret POC ultrasound
  - All cases involved failure to perform a complete ultrasound study or failure to perform in a timely manner
  - Most common exam type was DVT study
  - Majority of cases involved patient death

Strengths & Limitations

Strengths
- Provides valuable data on legal landscape of POC ultrasound
- Study was designed to identify cases where emergency physicians not only performed but could have performed an ultrasound exam. This allows for potential assessment of “deferred risk”.
Limitations
- Small n – Small number of cases limits ability to approximate any measure of risk to emergency physicians using POC ultrasound
- Selection bias – Cases settled out of court, cases with unreported decisions, cases not publically available (private negotiations, arbitration, sealed records, etc) not included in Westlaw database
- Limited assessment of other factors associated with each case: emergency physician ultrasound skills, access to ultrasound, level of facility support, barriers to perform ultrasound, medical decision making process

Author's Conclusions

“From 2008 to 2012, the Westlaw database reported no judicial decisions against an emergency physician performing POC ultrasound. The database reports five cases related to failure to perform an ultrasound examination that was within the scope of ACEP core emergency ultrasound applications in a timely manner. Further analyses using other legal data sources and insurance claim data are desired and further work is necessary to confirm these preliminary findings.”

Our Conclusions

This study provides reassuring evidence that emergency physicians are not significantly burdened by malpractice lawsuits relating to POC ultrasound use in their clinical practice. In a comprehensive search of publicly available federal and state US malpractice claims, only five cases were found to be associated with POC ultrasound. However, this number must be interpreted with caution. Rubin et al demonstrated that a very small percentage of paid malpractice claims in the US are judged in court (3.1%) while the majority are settled outside (96.9%). The Westlaw database used in this study was able to access only publicly available case data, or cases that were judged in court. Thus, it is difficult to draw generalizable conclusions about the legal risks associated with POC ultrasound from this study. Overall, this study reveals that within publicly available malpractice claims data, lawsuits relating to POC ultrasound are in the minority. While there is legal risk associated with use and failure to use available diagnostic modalities, emergency physicians should feel encouraged to incorporate POC ultrasound exams into their clinical practice.

The Bottom Line

Though the data is limited, there is some reassuring evidence that there is no significant legal burden associated with POC ultrasound used within the scope of ACEP core emergency ultrasound applications. Emergency physicians should continue to incorporate POC ultrasound into their clinical practice.

Authors

This post was written by Neha Chandra, MS4 at University of California, San Diego. It was reviewed by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. 1. Rubin, Jessica B., and Tara F. Bishop. "Characteristics of paid malpractice claims settled in and out of court in the USA: a retrospective analysis." BMJ open 3.6 (2013): e002985.
  2. Stolz, Lori, et al. "A review of lawsuits related to point-of-care emergency ultrasound applications." Western Journal of Emergency Medicine 16.1 (2015): 1.

November 18, 2017July 22, 2020

Case # 10: A Mechanical Issue

A 32 year old male was carrying a heavy pipe overhead with his right arm and slipped falling forward, onto the right side. He notes pain in the right shoulder, worse with any movement. His right arm is flexed and internally rotated for comfort.

Vitals: T 98.6 HR 95 BP 143/91 RR 14 O2 98% on RA

A bedside ultrasound of the right shoulder is performed, what is the next best step in management?

Answer and Learning Points

Answer

Shoulder dislocation reduction. The ultrasound image shows anterior displacement of the humeral head with respect to the glenoid fossa consistent with an anterior shoulder dislocation. A hematoma is also noted within the joint space which is very commonly associated with a traumatic shoulder dislocation.

Ultrasound diagnosis of anterior shoulder dislocation

Learning Points

- Ultrasound is useful for both the initial diagnosis and reduction confirmation of a shoulder dislocation, as well as for intra-articular injection of local anesthetic; however in a traumatic dislocation, an initial x-ray should be obtained to evaluate for any associated fracture.
- To perform the exam, a low frequency curvilinear transducer should be used. The operator should stand behind the patient, on the side of the affected shoulder, and place the ultrasound system directly in front of the patient for easy visualization. The probe should be placed on the posterior aspect of the scapula, parallel and just inferior to the scapular spine. This will allow direct visualization of the glenohumeral joint.
Proper probe placement for evaluation of glenohumeral joint.
- In a normal shoulder the glenoid and humeral head articulate nicely and this can be appreciated on ultrasound with internal and external rotation of the patient's arm, however with dislocation, the humeral head and glenoid will not be aligned. In anterior dislocation, the humeral head will be deep to the glenoid, while in a posterior dislocation, the humeral head will be more superficial to the glenoid.
Normal glenohumeral ultrasound anatomy
- Ultrasound is especially useful to confirm successful shoulder relocation and prevent both a prolonged stay in the emergency department waiting for a post reduction x-ray, as well as re-sedation if this was required for a difficult shoulder reduction.
- Lastly, this same ultrasound view can be used for in-plane needle guidance to provide intra-articular anesthesia using a lateral needle entry approach.
- For a 5 minute video tutorial on ultrasound for shoulder dislocation , click here to watch this excellent video at 5 Minute Sono.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Abbasi S, Molaie H, Hafezimoghadam P, et al. Diagnostic accuracy of ultrasonographic examination in the management of shoulder dislocation in the emergency department. Ann Emerg Med. 2013:1-6.
2. http://www.thepocusatlas.com/musculoskeletal/

November 10, 2017July 22, 2020

The effect of vessel depth, diameter, and location on US guided peripheral intravenous catheter longevity

Background

Nearly 30% of all patients who visit the ED in the US each year will require venous access. Bedside ultrasound-guided peripheral IVs (USGPIV) offer an alternative to central venous cannulation and external jugular cannulation for patients in which PIV access cannot be obtained, thereby reducing the risks of infection and the need for additional resources that are associated with the aforementioned procedures. The downside to USGPIVs lies in the longevity of this method of venous access, which introduces complications such as extravasation, tissue necrosis and disruption of access. Failure rates are high, with 8% of them failing within the first 8 hours, and 47% failing within the first 24 hours. The authors of this weeks article speculate that this is due to the nature of the vessels targeted by ultrasound (US), being that they are often deeper and smaller veins in locations that are otherwise difficult to access without specialized imaging. This article will explore the influence of various vessel characteristics on the success and longevity of the USGPIVs, including vessel depth, diameter, and location.

The effect of vessel depth, diameter, and location on US guided peripheral intravenous catheter longevity

Clinical Question

How do specific characteristics of a vessel determine the success and longevity of a USGPIV?

Methods & Study Design

Design
- A retrospective chart review of a previously gathered database of difficult intravenous access (DIVA) patients who underwent USGPIV placement in the ED
- Data included images and measurements of the vessel’s depth, diameter and location as well as survival time of the IV
Population
- Urban tertiary care center with a 4-yr EM residency and an US fellowship
- Study period: Dec 2007-May 2008
Inclusion criteria
- All DIVA patients: A DIVA patient is defined as someone with 2 failed peripheral IV attempts or a history of DIVA with inability to visualize or palpate a target vein on physical exam
- DIVA patient must have underwent successful USGPIV placement in ED
Exclusion criteria
- There were no specific exclusion criteria however patients were excluded for several reasons:
  - 18 for inability to establish USGPIV using study protocol
  - 12 for lack of charting to accurately determine time of IV removal
  - 2 for failure of consensus of at least 2 of the 3 blinded independent chart reviewers on timing or outcome of IV
Intervention
- USGPIVs were placed by 2 PGY-2s, 1 PGY-3, and 1 US fellow, all met ACEP guidelines (at least 10 USGPIVs previously performed)
  - Successful IV placement was defined as aspiration of 5 mL of blood and ability to flush the line without resistance
  - Only 20-gauge, 48-mm-long (Angiocath Autoguard;BD Medical Systems, Sandy, UT) catheters were used for USGPIV placement
  - During USGPIV placement, vessels were measured for depth and diameter, and location was noted on a diagram of the upper extremity
Outcomes
- - Failure rate of USGPIV based on depth, diameter, and location
    - 2 blinded independent chart reviewers followed successfully placed USGPIVs for 48 hours or until failure, whichever came first
    - Failures were defined as IVs that infiltrated, dislodged, stopped working or were discontinued prematurely
    - IVs removed on patients that no longer required access were not considered failures

Results

Calculated USGPIV survival curves for vessels at given depths and location from Fields et al.
- Statistical Analysis
  - Vessel depth divided into 3 zones: shallow (0.4 cm), intermediate (0.4-1.19 cm), and deep (≥1.2 cm); Intravenous diameter was divided into 4 groups (<0.3, 0.3-0.39, 0.4-0.49, and ≥0.5 cm);
  - Vessel location was divided into proximal (brachial region) and distal (antecubital fossa, forearm, or hand veins).
  - Kaplan-Meier estimator was used to measure time-to-failure and remove potential confounder of IVs that were removed for discharge or no longer needed
- Findings
  - At 48 hrs, 48 (32%) had failed because of dislodgment, infiltration, or patient discomfort
    - 20 (42%) infiltrated
    - 11 (23%) dislodged
    - 16 (33%) were not flushing
    - 1 removed for discomfort
    - 36 (24%) were removed for routine reasons
    - 67 (44%) were still in place and without incident
    - There was no difference in patient characteristics of IVs that failed vs. those that did not fail
  - Kaplan-Meier Survival Analysis
    - Depth: Survival probability excellent (1.00) for shallow vessels, moderate (0.62) for intermediate vessels, poor (0.29) for deep vessels STRONGEST PREDICTOR
    - Location: antecubital fossa or forearm associated with improved survival when compared with proximal placement in brachial or basilic vein (0.93 vs. 0.71)
    - Diameter: no significant difference
    - For each increase of 0.2 cm in depth, odds of failure at 48 hrs increases by hazard ratio of 1.36
    - Placement in proximal vs. distal location increases odds of failure by hazard ratio 2.76

Strengths & Limitations

Strengths
- No difference in patient characteristics between failed and successful USGPIVs
- Recruited difficult IV access patients from urban academic tertiary ED which is likely representative of true difficult access patient population and can be generalized to other EDs
- 2 independent reviewers used for retrospective chart review
Limitations
- Outcome variable (survivability) was gathered retrospectively; potential bias in rapid realization of IV failure and clear documentation
- Possible that failed catheters were documented as “removed” because they were no longer needed or another access was obtained
- Did not account for certain factors: nature of the infusion, how often IV accessed, movement of extremity, use of fixation device
- Only assessed using 20-gauge, 48-mm IV
- Small group of sonographers performed data collection, they may be more skilled than general population of emergency physicians

Author's Conclusions

“Ultrasound provides a useful rescue method for establishing IV access in patients with DIVA. The current study reveals 2 factors that significantly affect the durability of these IVs— depth and location. Using a 48-mm catheter, vessels of 1.2 cm or more deep have a high likelihood of USGPIV failure and should only be cannulated when other options are not available. Vessels of less than 0.4 cm deep yield the best USGPIV longevity. Forearm and antecubital sites are more enduring than those in the upper arm. Understanding of these associations will help the sonologist select the optimal vessel for successful USGPIV cannulation and longevity.”

Our Conclusions

Depth should be the primary consideration when selecting a vessel for USGPIV access. Due to high immediate failure rates, vessels of 1.2 cm deep or more deep should be avoided and other means of obtaining venous access should be considered. Providers should also take into consideration the location of IV placement. If it is anticipated that a patient will require IV access for longer than the immediate stay in the emergency department, then proximally-located IVs should be avoided given their high failure rate at 18 hours. This failure may be explained by the fact that proximal vessels are located closer to the axilla and usually embedded in looser skin containing more subcutaneous fat with greater potential for dislodgment upon movement of the extremity. Therefore, providers should consider how long the patient will be requiring access as well as how often the patient will be required to move the extremity in making decisions regarding venous access.

The Bottom Line

USGPIVs that are placed in more superficial (<1.2 cm) and distal (forearm/antecubital space) veins have a significantly higher likelihood of survival at 48 hours and these factors should strongly be considered when evaluating for a target for IV placement.

Authors

This post was written by Courtney Shay, MS4 at George Washington University. It was reviewed by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Fields JM, e. (2017). The effect of vessel depth, diameter, and location on ultrasound-guided peripheral intravenous catheter longevity. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 10 November 2017, from https://www.ncbi.nlm.nih.gov/pubmed/22078967

November 4, 2017July 22, 2020

Case # 9: A Transplant Dilemma

A 52 year old male with a h/o kidney transplant presents to the emergency department with pain over his transplanted kidney site (right pelvic region). He also notes increased weakness, nausea and a significant decrease in urine output. He denies any fever. He states he is compliant with his anti-rejection medications.

Vitals: T 99.0 HR 105 BP 165/91 RR 18 O2 98% on RA

A bedside ultrasound is performed, what is the next best step in management?

Answer and Learning Points

Answer

Insertion of foley catheter. The clip above demonstrates severe hydronephrosis of the patient's transplanted kidney. A foley was inserted in the emergency department with immediate output of 1.5 L of clear urine. The patient was found to be in renal failure secondary to his urinary outlet obstruction. He was admitted to transplant surgery and his renal function improved over the next day; he was discharged home with a leg bag and urology follow up. Below is a repeat ultrasound of his transplanted kidney after drainage of his bladder:

Learning Points

- Urinary obstruction in a transplanted kidney can be missed initially as pain over the patient's graft site and decreased urine output is easily contributed to possible rejection or infection.
- The differential diagnosis of acute renal failure in the transplanted kidney is broad (see table below) and emergency department management should include a thorough evaluation for prerenal, intrinsic and post renal causes, in consultation with a transplant service.
- All renal transplant patients presenting with acute renal failure should have a formal renal ultrasound with doppler to evaluate the graft however often this is not available immediately and a bedside ultrasound can assist with rapid identification of acute urinary obstruction.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Kadambi PV., Brennan DC., Chon J. (2017). Evaluation and diagnosis of the patient with renal allograft dysfunction. In T.W. Post, B. Murphy, & A. Lam (Eds.), UptoDate. Available from https://www.uptodate.com/contents/evaluation-and-diagnosis-of-the-patient-with-renal-allograft-dysfunction

October 30, 2017July 22, 2020

Focused Transesophageal Echocardiography by Emergency Physicians is Feasible and Clinically Influential

Background

Cardiac ultrasound is frequently used in the emergency department (ED) to effectively identify pericardial effusion, differentiate causes of shock, assess left ventricular function, and guide cardiopulmonary resuscitation (CPR). However, cardiac ultrasound employed in the ED is usually transthoracic echocardiography (TTE) as opposed to transesophageal echocardiography (TEE). TTE can often be limited, especially in critically ill patients and patients with high BMI. TEE offers the ability to reliably obtain continuous high-quality images that can be performed without interrupting CPR. Despite this, TEE is not often employed in the ED due to a variety of factors, including transducer cost, invasiveness, physician training, and hospital culture.

Focused Transesophageal Echocardiography by Emergency Physicians is Feasible and Clinically Influential: Observational Results from a Novel Ultrasound Program

Clinical Question

Is TEE performed by emergency medicine trained physicians, in the emergency department setting, feasible and does it provide clinical utility?

Methods & Study Design

Design
- Retrospective Review
Population
- Study performed during a TEE in the ED pilot program by an academic emergency medicine program comprising 2 separate EDs, one of which is a regional trauma center.
- All patients who underwent TEE in the ED during the 2-year program period were included.
Exclusion criteria
- None
Intervention
- TEE was performed on critically ill, intubated patients. Most commonly, the mid-esophageal 4-chamber view, followed by the transgastric short axis, mid-esophageal long axis, and bicaval views were obtained.
OutcomesThe clinical impact of TEE, divided into two categories:
- - Diagnostic influence on clinical decision making
  - Therapeutic influence on procedures, medications, fluids, and CPR

Results

- 54 TEE exams performed with 100% probe insertion success rate
  - 83% on first attempt
  - 11% required multiple attempts
  - 6% required use of a laryngoscope
  - 98% of exams produced images that were interpretable by the operator
- TEE was diagnostically influential in 78% of cases
  - Excluded cardiac cause of arrest (56%)
  - Identified depressed left ventricular function (15%)
  - Identified hypovolemia (13%)
  - Identified regional wall motion abnormalities (6%)
  - Identified aortic dissection (4%)
- TEE was therapeutically influential in 67% of cases
  - Influenced changes to CPR (43%)
  - Directed cessation of resuscitation (30%)
  - Guided hemodynamic support (26%)
- No major adverse effects from probe placement identified

Strengths & Limitations

Strengths
- TEE exams were performed successfully by 14 different emergency physicians at 2 separate sites after only 4 hours of training, which demonstrated well the feasibility of TEE use in the ED on a more widespread basis.
- Well-described outcomes
Limitations
- Retrospective
- Relatively small sample size
- No comparison with TTE

Author's Conclusions

“ED- based TEE showed a high degree of feasibility (98% determinate rate) and clinical utility, with a diagnostic and therapeutic influence seen in the majority of cases. Focused TEE demonstrates the most promise in patients who are intubated and have either undifferentiated shock or cardiac arrest.”

Our Conclusions

This study demonstrates that performing TEE in the ED is both feasible and safe, and can be implemented with limited training of the physician staff. It also shows that TEE does have some clinical utility in the ED, specifically the detection of aortic dissection. However, the most common therapeutic effect noted in the study was the assessment of CPR quality, which can typically be assessed with less invasive means such as femoral pulse palpation and waveform capnography. The other common findings noted in the study (i.e. depressed ejection fraction, hypovolemia, guidance of hemodynamic support) can typically be assessed with more traditional and less invasive TTE. In order to truly evaluate the utility of TEE in the ED, a prospective study showing a comparison of TEE with TTE, and other less invasive diagnostic modalities, would need to be performed. That being said, having the ability to diagnose aortic dissection at the bedside and to guide resuscitation via direct cardiac visualization during ongoing CPR are important considerations. This is a promising pilot study that opens up the door for further research evaluating the utility of TEE in the ED, however at this point, it is not clear whether it will perform better than traditional TTE and other clinical adjuncts in both diagnostic and therapeutic abilities.

The Bottom Line

Performing TEE in the ED is both feasible and safe, and does provide useful clinical information. However more studies are required in order to assess the true clinical utility of this modality.

Authors

This post was written by Toby Matt, MS4 at UCSD. It was reviewed by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Arntfield R, e. (2017). Focused Transesophageal Echocardiography by Emergency Physicians is Feasible and Clinically Influential: Observational Results from a Novel Ultraso... - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 30 October 2017, from https://www.ncbi.nlm.nih.gov/pubmed/26508495

October 21, 2017July 22, 2020

Case # 8: A Case of Comparision

A 40 year old male presents to the emergency department with pain to the entire right thumb and wrist for 1 day. He notes that he suffered a small puncture wound to his right thumb 1 day ago while working on his car. The patient has notable circumferential, non-erythematous swelling to his right thumb with tenderness along the flexor tendon. There is also fullness of the dorsum of his wrist. He is holding his fingers flexed and has pain radiating into the wrist with any movement of his fingers or wrist, especially with extension of his fingers.

Vitals: T 98.7 HR 90 BP 132/81 RR 13 O2 98% on RA

A bedside ultrasound is performed, what is the next best step in management?

Normal Left Thumb in Long Axis

Abnormal Right Thumb in Long Axis

Answer and Learning Points

Answer

Empirical antibiotic therapy and orthopedic surgery consultation for infectious flexor tenosynovitis (FTS). The patient meets 4 out of 4 Kanavel's signs and has ultrasound evidence of FTS suggested by a thickened tendon with surrounding anechoic fluid.

Short Axis View of Right 1st Digit demonstrating hypoechoic fluid surrounding tendon.

Learning Points

- FTS is often a clinical diagnosis and examination (Kanavel's signs) is thought to have high sensitivity (91.4-97.1%) but low specificity (51.3-69.2%) for infectious FTS [2]; however a negative exam does not rule it out completely.
  - Kanavel's signs include:
    - Finger held in slight flexion
    - Fusiform swelling
    - Tenderness along the flexor tendon sheath
    - Pain with passive extension of the digit
- FTS is treated with empirical antibiotic therapy as well as early surgical debridement and drainage. Delays in diagnosis can lead to local spread of infection, compartment syndrome and necrosis.
- While there is not high quality evidence describing the use of emergency department point of care ultrasound (POCUS) to diagnose FTS, previous radiographic studies have found ultrasound to be more sensitive than clinical exam for detecting tenosynovitis [3].
- Common ultrasound findings for FTS include:
  - Hypoechoic or anechoic edema or debris within the tendon sheath
  - +/- thickening of the tendon sheath
- The ultrasound examination should be performed using a linear probe, examining the affected tendon (and normal tendon on other hand for comparison), in both the longitudinal and transverse plane.
  - Small rocking or fanning motions should be used to ensure perpendicular orientation of the probe to the tendon to avoid artifact secondary to anisotropy.
- As in all uses of POCUS in the emergency department setting, findings should be interpreted in conjunction with clinical examination and history when evaluating for infectious FTS. We believe POCUS for infectious FTS can be used to increase diagnostic certainty and even expedite care and aggressive treatment however a normal exam should not be used to rule out this diagnosis.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Padrez, K., Bress, J., Johnson, B., & Nagdev, A. (2015). Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. Western Journal Of Emergency Medicine, 16(2), 260-262. doi:10.5811/westjem.2015.1.24474
2. Kennedy CD, e. (2017). Differentiation Between Pyogenic Flexor Tenosynovitis and Other Finger Infections. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 21 October 2017, from https://www.ncbi.nlm.nih.gov/pubmed/28720000
3. Hmamouchi I, Bahiri R, Srifi N, et al. A comparison of ultrasound and clinical examination in the detection of flexor tenosynovitis in early arthritis. BMC Musculoskelet Disord. 2011;12(1):91.

October 8, 2017July 22, 2020

Variability in Interpretation of Cardiac Standstill Among Physician Sonographers

Background

The use of point-of-care echocardiography to inform termination or continuation of cardiopulmonary resuscitative efforts remains controversial [1,2]. Current understanding of its utility in prognostication is limited by varying definitions of cardiac activity. Definitions of cardiac standstill range from absence of “organized contractile activity (nonfibrillating) with a decrease in chamber size” to absence of “any visible movement of the myocardium, excluding movement of blood within the cardiac chambers or isolated valve movement” to absence of “any detected atrial, valvular, or ventricular motion within the heart” [3-5]. Without a consistent definition of cardiac standstill, it is difficult to interpret studies reporting conflicting resuscitation outcomes in cardiac arrest.

Variability in Interpretation of Cardiac Standstill Among Physician Sonographers

Clinical Question

What is the interrater reliability among providers in classification of cardiac standstill in point-of-care echocardiography?

Methods & Study Design

Design
- Cross-sectional convenience sample survey
Population
- Eligible: Residents, fellows, and faculty practicing in emergency medicine, critical care, or cardiology in attendance at one of six weekly emergency medicine (EM) conferences held at the following locations:
  - Icahn School of Medicine at Mount Sinai
  - Beth Israel Medical Center
  - St. Luke’s-Roosevelt Hospital
Exclusion criteria
- Providers who had previously participated at a prior conference
Intervention
- Participants were presented with the following clinical scenario: “55-year-old man in cardiac arrest who remains pulseless after 20 minutes of CPR”
- Participants were shown 15 clips (6 seconds each, looped for 20 seconds total) presenting a variety of sonographic features
- Asked to identify presence or absence of cardiac activity
- Responses transmitted via remote polling devices
- No definition of cardiac activity was provided
Outcomes
- Primary: interrater reliability in interpreting cardiac standstill (Krippendorff’s alpha coefficient)
- Secondary: subgroup analyses by specialty, training level, and self-described point of care (POC) ultrasound experience

Results

- 127 participants (majority EM residents with basic ultrasound skills)
- Overall moderate agreement with respect to identifying cardiac standstill (alpha 0.47)
- Clips with stronger agreement:
  - No myocardial contraction
  - Myocardial contraction
  - Strong myocardial contraction
- Clips with poorer agreement:
  - Valve flutter
  - Mechanical ventilation
  - Weak myocardial contraction
- Moderate agreement across all training levels and self-reported ultrasonographic skill levels

Strengths & Limitations

Strengths
- All participants saw the same clips
- Response time limited (similar to clinical practice)
Limitations
- Bias: recruitment from academic conferences
- Majority with no or basic self-reported ultrasonographic skill level
- Reported discussion among participants throughout survey

Author's Conclusions

“Our results support the possibility that previous studies have been subject to variability in the interpretation of cardiac standstill.”

Our Conclusions

We agree with the authors’ conclusions that there appears to be substantial variability in the interpretation of cardiac standstill. This study highlights a weakness in the current literature examining the utility of POC echocardiography used during resuscitation futility assessment. While this study does not provide data on clinical outcomes of standstill misclassification, it identifies a potential weakness in the available research. It is difficult to interpret studies reporting outcomes after standstill (such as meaningful survival) when the predictor is not consistently identified.

As a follow-up study, it would perhaps be interesting to see how the interrater reliability changes when participants are provided with a clear definition of cardiac standstill. Does the variability persist even with a uniform definition? If this improves interrater reliability it would provide additional support for the need for a consensus definition across future studies.

The Bottom Line

There is significant variability in classification of cardiac standstill among providers. A uniform definition of standstill may reduce this variability and aid in the interpretation of studies reporting conflicting outcomes after cardiac arrest.

Authors

This post was written by Carly Dougher, MS4 at UCSD. It was reviewed by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Blyth, L., Atkinson, P., Gadd, K. & Lang, E. Bedside Focused Echocardiography as Predictor of Survival in Cardiac Arrest Patients: A Systematic Review: Echocardiography in Cardiac Arrest. Acad. Emerg. Med. 19, 1119–1126 (2012).
2. Cohn, B. Does the Absence of Cardiac Activity on Ultrasonography Predict Failed Resuscitation in Cardiac Arrest? Ann. Emerg. Med. 62, 180–181 (2013).
3. Schuster, K. M. et al. Pulseless Electrical Activity, Focused Abdominal Sonography for Trauma, and Cardiac Contractile Activity as Predictors of Survival After Trauma: J. Trauma Inj. Infect. Crit. Care 67, 1154–1157 (2009).
4. Gaspari, R. et al. Emergency department point-of-care ultrasound in out-of-hospital and in-ED cardiac arrest. Resuscitation 109, 33–39 (2016).
5. Kim, H. B., Suh, J. Y., Choi, J. H. & Cho, Y. S. Can serial focussed echocardiographic evaluation in life support (FEEL) predict resuscitation outcome or termination of resuscitation (TOR)? A pilot study. Resuscitation 101, 21–26 (2016).

October 2, 2017July 22, 2020

Case # 7: A Case of Asymmetry

A 22 year old male presents to the emergency department with a sore throat for 1 week. The pain is predominately on the left side and is associated with difficulty opening his mouth and fever. He was placed on amoxicillin 3 days ago but notes that his symptoms have progressed. He appears uncomfortable.

Vitals: T 101.4 HR 105 BP 132/81 RR 14 O2 98% on RA

A bedside ultrasound is performed, what is the next best step in management?

Answer and Learning Point

Answer

Incision and drainage. The patient presents with lateralizing pharyngitis symptoms associated with fever and trismus concerning for peritonsillar abscess (PTA). The ultrasound clip demonstrates a well circumscribed, hypoechoic fluid collection abutting the left tonsil confirming this diagnosis (see color overlay below).

Previously, physicians relied solely on the physical exam findings of peritonsillar swelling and uvular deviation to make the diagnosis of PTA. However, this approach lacks accuracy, with studies showing a sensitivity and specificity of 75% and 50% respectively [1]. This uncertainty leads to increased CT utilization, repeat drainage attempts and ENT consultation. Intraoral ultrasound is a novel technique that can be used by emergency physicians (EP), both for diagnosis and drainage of PTA. A recent randomized control trial found the use of intraoral ultrasound (vs. traditional landmark technique) to be significantly more reliable for differentiating between PTA and peritonsillar cellulitis. Additionally, this study also demonstrated increased success in PTA drainage by EPs with the use of intraoral ultrasound guidance [2].

Learning Points

- An endocavitary probe should be used when PTA is suspected to differentiated between PTA and peritonsillar cellulitis; and assist with drainage if necessary.
- If an endocavitary probe is not available, or if the patient cannot open their mouth wide enough to pass the probe, an alternative approach, known as the telescopic submandibular approach can also be used and is explained here.
- When using ultrasound, the distance from the oral mucosa to the center of the PTA should be measure. The plastic sheath of an 18-gauge needle (preferably a spinal needle to allow the barrel of the syringe to be outside of the patients mouth) should be cut to this length to prevent puncturing any deeper structures during drainage.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Scott PM, e. (2017). Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 2 October 2017, from https://www.ncbi.nlm.nih.gov/pubmed/10435129
2. Costantino TG, e. (2017). Randomized trial comparing intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 2 October 2017, from https://www.ncbi.nlm.nih.gov/pubmed/22687177