Small Bowel Obstruction & PoCUS

Small Bowel Obstruction & PoCUS – Medical Student Pearl

Patrick Rogers, Clinical Clerk (CC3)

Memorial University of Medicine Class of 2021

Reviewed by Dr. Kavish Chandra

Small bowel obstructions (SBO) are a common cause of acute abdominal pain in emergency departments across Canada. Diagnostic imaging plays a key role in the diagnosis and management of SBO as the history, clinical examination and laboratory investigations lack the sensitivity and specificity needed. Furthermore, diagnostic imaging may help differentiate SBO from other causes of abdominal pain (hernias, malignancies, intussusception, etc).

Historically, plain film abdominal radiography (AXR) has been an initial investigation in emergency departments when an SBO is suspected.  However, the current literature suggests that abdominal radiography is a relatively poor test for the diagnosis or exclusion of SBO when compared to other available modalities like US, CT, or MRI. In fact, multiple studies argue for the reduction of abdominal x-rays, especially when patients come in presenting with general abdominal tenderness. 1 Fortunately, there exists a compelling alternative: point of care ultrasound (PoCUS), and is being increasingly used as a first line investigation for SBO. 2

There are several reasons why physicians may start to choose PoCUS over traditional diagnostic modalities:

  • PoCUS avoids the radiation exposure that patients receive from cumulative plain films and abdominal CT’s. 3
  • PoCUS has been shown to reduce time to diagnosis and treatment in comparison to abdominal plain films. 3
  • PoCUS is more sensitive/specific modality when compared to abdominal plain film. 4
  • PoCUS allows for serial examination in the ED. 5
  • PoCUS may be rapidly available to centers with limited access to CT scanner. 6

The current evidence is highly favorable for the diagnostic efficacy of PoCUS in SBO. Here are the findings of peer-reviewed studies on the subject (published between 2013-2020):

  • PoCUS has high diagnostic accuracy and may also decrease time to diagnosis of SBO in comparison to other imaging modalities like CT and plain film.2
  • PoCUS has been found to have superior diagnostic accuracy for SBO in comparison to plain abdominal radiography. 4
  • PoCUS has been shown to be an accurate tool in the diagnosis of SBO with a consistently high sensitivity of 94-100% and specificity of 81-100%. 5
  • Current evidence suggests PoCUS is comparable in sensitivity and specificity to a CT scan when diagnosing SBO. 6
  • Ultrasound was found to be equivalent to CT in terms of diagnostic accuracy with a sensitivity of 92.31% (95% CI, 74.87% to 99.05%) and a specificity of 94.12% (95% CI, 71.31% to 99.85%) in the diagnosis of SBO. 7
  • In a study comparing XR, US, CT, and MRI, the abdominal x-ray was shown to be to be the least accurate imaging modality for the diagnosis of SBO. AXR’s were found to have a positive likelihood ratio of 1.64 (95% CI 1.07 to 2.52). In contrast, CT and MRI were both quite accurate in diagnosing SBO with positive likelihood ratios of 3.6 (95% CI = 2.3 to 5.4) and 6.77 (95% CI = 2.13 to 21.55). The use of ultrasound was found to have a positive likelihood ratio of 9.55 (95% CI = 2.16 to 42.21) and a negative likelihood ratio of 0.04 (95% CI = 0.01 to 0.13) for beside scans. 4

There are two major barriers identified in the literature that may prevent the effective use of PoCUS in the diagnosis of SBO. First, not every emergency physician has been trained on the use of PoCUS. Fortunately, two recent studies show that even minimally trained ED physicians can use it accurately. 8 Secondly, some surgeons have argued that PoCUS does not show the location of the obstruction accurately. This becomes a concern when the care team elects for surgical management of the patient’s SBO. However, recent evidence suggests that PoCUS may lead to quicker time to diagnosis and enteric tube insertion in conservative management. 8

Finally, how can learners use this technology? 5 Here are some specific sonographic findings to look for when evaluating a patient for SBO with US:

 

  • Dilatation of small bowel loops > 25 mm *
  • Altered intestinal peristalsis *
  • Increased thickness of the bowel wall
  • Intraperitoneal fluid accumulation

Figure 1. Dilatation of small bowel loops. Image courtesy Dr. Kavish Chandra

Figure 2. Altered intestinal peristalsis*. Image courtesy Dr. Kavish Chandra

Figure 3. – abnormal peristalsis “to and fro”9

References

  1. Denham G, Smith T, Daphne J, Sharmaine M, Evans T. 2020. Exploring the evidence-practice gap in the use of plain radiography for acute abdominal pain and intestinal obstruction: a systematic review and meta-analysis. International Journal of Evidence Based Healthcare. DOI: 10.1097/XEB.0000000000000218
  2. Guttman J, Stone M, Kimberly H, Rempell J. 2015. Point of care ultrasonography for the diagnosis of small bowel obstruction in the emergency department. CJEM. DOI: 10.2310/8000.2014.141382
  3. Flemming H, Lewis D. 2016. SBO- A New Focus for PoCUS. Saint John Regional Hospital Department of Emergency Medicine
  4. Taylor M, Lalani N. 2013. Adult small bowel obstruction. Academic Emergency Medicine. DOI: 10.1111/acem.12150
  5. Pourman A, Dimbil U, Shokoohi H. 2018. The accuracy of point of care ultrasound in detecting small bowel obstruction in emergency department. Emergency Medicine International. DOI: 10.1155/2018/3684081
  6. Gottlieb M, Peska, G, Pandurangadu A, Nakitende D, Takhar S, Seethala R. 2018. Utilization of ultrasound for the evaluation of small bowel obstruction: A systematic review and meta-analysis. The American Journal of Emergency Medicine. DOI: 10.1016/j.ajem.2017.07.085
  7. Tamburrini S, etal. 2019. Diagnostic accuracy of ultrasound in the diagnosis of small bowel obstruction. Diagnostics. DOI: 10.3390/diagnostics9030088
  8. Carpenter C. 2013. The end of X-Rays for suspected small bowel obstruction? Using evidence-based diagnostics to inform best practices in emergency medicine. Academic Emergency Medicine. https://doi.org/10.1111/acem.12143
  9. The PoCUS Atlas. https://www.thepocusatlas.com/bowel-gi

Copyedited by Dr. Mandy Peach

Continue Reading

EM Reflections Nov 2020 – Chest pain; expand the differential!

Authored and Edited by Dr. Mandy Peach

 

Big thanks to Dr. Paul Page for leading the discussions in November.

All cases are imaginary, but highlight learning points that have been identified as potential issues during rounds.

Chest pain is a huge topic – this is not a deep dive, but hopefully a helpful review of some useful information for on shift. This post assumes a basic knowledge of bedside ultrasound.

Chest Pain

  • The ‘don’t miss’ diagnoses
  • The ultrasound findings that can be helpful in shortening the differential
  • The evidence for ultrasound in some chest pain diagnoses
  • Select decision rules in chest pain
  • D-dimer and troponin and their uses
  • Ultrasound findings of cholecystitis

Case

48 yo male presents to the ED with 4 hours of substernal CP. He describes the pain as sudden onset and waking him from sleep overnight. He feels sweaty and has had 2 episodes of nausea/vomiting. He denies any fever or diarrhea. He had a similar episode last week that spontaneously resolved after 3-4 hours. He has no history of exertional chest pain. His cardiac risk factors include hypertension and his father died of ‘heart problems’ in his late 60’s.

An ECG is completed:

On exam his vital signs are within normal limits. He appears slightly diaphoretic and uncomfortable. Cardiorespiratory exam is unremarkable.

 

What are the BIG can’t miss diagnoses for chest pain? What bedside tool can be helpful in diagnosing some of these conditions?

Acute Myocardial Infarction (MI)

Pulmonary Embolism (PE)

Tension Pneumothorax

Aortic Dissection

Cardiac Tamponade

Esophageal Rupture

 

The ECG is unremarkable for ischemic change. You order a cardiac work up, including a CXR. While you await these results, you reach for your nearest ultrasound probe. You perform a cardiac and lung scan:

Figure 1 – normal subxiphoid view of the heart

Figure 2: Normal lung slide with visible A lines

You do not see any large pericardial effusion and on an eyeball observation the heart appears to have grossly normal form and function. The lung scan appears unremarkable with no sign of pneumothorax after viewing multiple rib spaces anteriorly and laterally.

 

How accurate is ultrasound at helping you rule in/out some of the major chest pain diagnoses?

Cardiac tamponade – Trained emergency physicians using beside ultrasound are quite effective at identifying significant pericardial effusions with a sensitivity of 96% and specificity of 98%1.

Figure 3: Large pericardial effusion with collapsing of RV

 

Pneumothorax – Lack of lung sliding and comet tails has a specificity of over 90% in ruling in pneumothorax. Time constraints? 1 view has comparable sensitivity to 4 views in picking up a clinically significant pneumothorax2

Figure 4: Absence of lung sliding or comet tails indicating pneumothorax

 

Pulmonary Embolism – Although no one finding is pathognomonic for PE, signs of RV dysfunction in the right clinical context is certainly suggestive of acute PE. Findings of:

  • RV enlargement equal or greater to that of the LV
  • RV systolic dysfunction (RV free wall hypokinesis) or
  • bowing of the RV into LV

have a 99% specificity for PE3.

Figure 5: Enlarged RV with free wall hypokinesis at the apex (McConnell’s sign)

Figure 6: Bowing of RV into LV in parasternal short view “D sign”

For advanced scanners, in patients with abnormal vitals (tachycardiac and hypotensive):

  • normal TAPSE
  • normal RV size
  • absence of RV flattening
  • absence of McConnell’s sign

significantly decreases the post-test probability for PE4

 

Aortic dissection – very specific findings – if you see a dissection flap you found it! If not, it’s still a high risk diagnosis you wouldn’t want to miss. There is evidence that when getting advanced cardiac views, suprasternal notch views and visualizing the abdominal aorta the sensitivity of POCUS is 86%5, however this did not translate into mortality benefit and is likely of more benefit for advanced scanners.

 

With normal vitals and ultrasound findings you feel confident there is no pneumothorax or tamponade. The probability of PE seems quite low given the history. Is there an objective way to risk stratify your patient for PE risk?

 

Apply the PERC rule 6 in the targeted low risk patients like this one where your physician gestalt of likelihood of PE < 15% . In the appropriate population this tool has a sensitivity of 96%;

The probability of him having a PE is < 2%.

 

You revisit the history and physical exam keeping in mind your remaining diagnoses of aortic dissection and esophageal rupture.

Are there any tools I can use to help decide if my patient is high risk for aortic dissection?

This tool is for low-moderate risk patients where dissection is in the differential.  When this rule was applied to a retrospective population only 4% of dissections were missed. When adding a normal CXR the miss rate decreased to 2.7%. Each feature equals 1 point. Essentially the absence of any high risk feature essentially rules out aortic dissection7. If more than 1 high risk feature, proceed to CT-A. If ≤ 1 this tool suggest ordering d-dimer.

Does d-dimer help rule out aortic dissection?

It’s controversial. If your patient is low risk and dissection isn’t high on your differential, a normal d-dimer doesn’t really add any value. If you order anyways and it is positive, it may lead to unnecessary testing. It certainly should not be used in isolation. The above tool combined with d-dimer had a sensitivity of 98.8% in one study, however this has not been externally validated8 – proceed with caution.

Your patient has no high risk features for aortic dissection.

 

Your patient did have episodes of vomiting – could they have a ruptured esophagus (Boerhaave syndrome)?

Mackler’s triad – vomiting, chest pain and subcutaneous emphysema – is present in 14-25% of cases so certainly not reliable. Patients can present with mediastinitis and abnormal vitals.CXR findings include 10:

With a normal CXR and normal vitals this is less likely.

 

So, you’ve considered the major diagnoses for chest pain and cardiac ischemia is left to consider – your first troponin result just become available – it is within normal range.

 

Can you use a single troponin to rule out a cardiac event?

You are now 4 hours from the onset of the event. Over his visit you have ordered a second ECG which is also normal. The troponin is  normal – you feel more reassured.  But your patient does have some risk factors for cardiac disease. You need to decide how at risk your patient is. You use the HEART score 11to help stratify:

Your calculated heart score is 3 which is low risk.

“A single undetectable hs-troponin after 3 hours of symptom onset or a delta 2-hr hs-troponin T <4ng/L plus normal serial ECGs and a HEART score of 0-3 rules out acute MI and lowers 30-day MACE to well below 1%, a threshold below which ancillary testing may cause more harm than benefit12.”

You feel quite confident your patient has no acute life-threatening cause of chest pain. You settle the pain and nausea in the ED and feel his is safe to go home. You suspect gastritis.

3 days later on shift you recognize the same patient – he again is complaining of chest pain, but today he looks much worst. You grab his chart – he is mildly tachycardiac, but otherwise vitals are normal. ECG again looks normal.
Today the patient describes having worsening nausea, fatigue and chest pain. His pain is more persistent and is not relieved with OTC medication at home. When you ask him to point to the pain he points towards his epigastric area – not substernal as he previously complained of.

This visit you complete an abdominal exam and find significant RUQ tenderness.

 

What are some other causes of chest pain, that although not immediately life threatening, should be considered13?

 

You grab your ultrasound probe as you suspect cholecystitis, what are the ultrasound findings?

Thickened gb wall > 3.5mm and fluid surrounding the gallbladder as seen above14.

You confirm cholecystitis and consult surgical service. On formal imaging the radiologist is concerned for potential perforation of the gallbladder.

Bottom line – chest pain has a broad differential! Grab your ultrasound probe and use some evidence based tools to help narrow your differential. Once life threatening causes ruled out consider other causes that can still affect patient morbidity.

 

References and further reading:

  1. Mandavia, Hoffner, Mahaney, Henderson (2001). Bedside echocardiography by emergency physicians. Annals of Emergency Medicine, Vol 38 (4); 377-382
  2. Michael Prats, MD. Comparison of Four Views Versus Single View for Pneumothorax. Ultrasound G.E.L. Podcast Blog. Published on November 07, 2016. Accessed on December 07, 2020. Available at https://www.ultrasoundgel.org/6.
  3. Pulmonary Embolism. The Evidence Atlas, The POCUS Atlas https://www.thepocusatlas.com/ea-echo
  4. Michael Prats. Focused Echo for Pulmonary Embolism in Patients with Abnormal Vital Signs. Ultrasound G.E.L. Podcast Blog. Published on February 17, 2020. Accessed on December 07, 2020. Available at https://www.ultrasoundgel.org/86.https://www.ultrasoundgel.org/posts/KsPSovvURE1CN7eZYELz1w
  5. Michael Prats. Return of the Aortic Dissection – POCUS Accuracy and Time. Ultrasound G.E.L. Podcast Blog. Published on August 31, 2020. Accessed on December 05, 2020. Available at https://www.ultrasoundgel.org/97.
  6. https://www.mdcalc.com/perc-rule-pulmonary-embolism
  7. Ohle, McIsaac, Atkinson (2019). How do I rule out aortic dissection? Just the Facts. CJEM 21(2): 34-36
  8. Nazerian, Mueller, Soeiro, Leidel, Salvadeo, Giachino et al. (2017). Diagnostic Accuracy of the Aortic Dissection Detection Risk Score Plus D-Dimer for Acute Aortic Syndromes: The ADvISED Prospective Multicenter Study. Circulation 137 (3): 250-258
  9. Cadogan, M. Boerhaave syndrome. Life in the Fast Lane. Published on Nov 3, 2020. https://litfl.com/boerhaave-syndrome/
  10. Diaz, G (2018). Boerhaaeve Syndrome. https://www.grepmed.com/images/5441/diagnosis-boerhaave-syndrome-signs
  11. Heart Score https://www.heartscore.nl/
  12. Low Risk Chest Pain and High Sensitivity Troponin – A Paradigm Shift. EM Cases. Published July 30, 2019. https://emergencymedicinecases.com/low-risk-chest-pain-high-sensitivity-troponin/
  13. Chest Pain. CanadiEM. Published June 1, 2020. https://canadiem.org/crackcast-e214-chest-pain/
  14. Flemming, Lewis, Henneberry. PoCUS – Measurements and Quick Reference. SJRHEM. Published 2017. http://sjrhem.ca/pocus-measurements-quick-reference/

All ultrasound gifs from The PoCUS Atlas https://www.thepocusatlas.com/

 

 

 

Continue Reading

Color Flow Doppler to Assess Cardiac Valve Competence

Color Flow Doppler to Assess Cardiac Valve Competence

Resident Clinical Pearl (RCP) April 2019

Dr. Scott Foley – CCFP-EM PGY3 Dalhousie University, Halifax NS

Reviewed by Dr. David Lewis

 


 

Background:

When colour Doppler is initiated, the machine uses the principals of the Doppler effect to determine the direction of movement of the tissues off which it is reflecting.

The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to a wave source. It was named after the Austrian physicist Christian Doppler who first described the phenomenon in 1842. The classic example is the change in pitch of a siren heard from an ambulance as it moves towards and away from an observer.

These principles are applied to POCUS in the form of colour Doppler where direction of flow is reflected by the colour (Red = moving towards the probe, Blue = moving away from the probe), and the velocity of the flow is reflected by the intensity of the colour (brighter colour = higher velocity).
*Note: the colour does not represent venous versus arterial flow.

 

The use of colour Doppler ultrasound can be useful in the emergency department to determine vascular flow in peripheral vessels as well as through the heart. It is one way to determine cardiac valve competency by focusing on flow through each valve.


 

Obtaining Views:

To optimize valve assessment, proper views of each valve must be obtained. It is best to have the direction of the ultrasound waves be parallel to the direction of flow. External landmarks for the views used are seen below:

  • Mitral Valve and Tricuspid Valve: The best view for each of these is the apical 4 chamber view. If unable to obtain this view, the mitral valve can be seen in parasternal long axis as well.
  • Aortic Valve: The best view is the apical 5 chamber or apical 3 chamber but are challenging to obtain. Instead, the parasternal long axis is frequently used.
  • Pulmonic Valve: Although not commonly assessed, the parasternal short axis can be used.
  • Visit 5minutesono.com for video instruction on obtaining views

Parasternal long axis: MV, AV

Parasternal short axis: PV, TV

Apical 4 chamber: TV, MV


 

Assessing Valvular Competency:

How to examine valvular competency:

  1. Get view and locate valve in question
  2. Visually examine valve: opening, closing, calcification
  3. Use colour Doppler:
    1. Place colour box over valve (as targeted as possible (resize select box) to not include other valves)
    2. Freeze image and scroll through images frame by frame
    3. Examine for pathologic colour jets in systole and diastole
  4. Estimating severity:
    1. Grade 1 – jet noticeable just at valve
    2. Grade 2 – jet extending out 1/3 of atrium/ventricle
    3. Grade 3 – jet extending out 2/3 of atrium/ventricle
    4. Grade 4 – jet filling entire atrium/ventricle

See video tutorial below for more


Mitral Regurgitation A4C

Tricuspid Regurgitation A4C

Aortic Stenosis PSLA


Bottom line:

Color flow Doppler on POCUS is a straightforward way to assess for valvular competency in the Emergency Department. A more detailed valvular assessment requires skill, knowledge and experience.

 


Useful Video Tutorials:

Mitral Regurgitation

 

Aortic Stenosis vs Sclerosis

Tricuspid Valve


References:

  1. https://www.radiologycafe.com/medical-students/radiology-basics/ultrasound-overview
  2. By Patrick J. Lynch and C. Carl Jaffe – http://www.yale.edu/imaging/echo_atlas/views/index.html, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=21448310
  3. 5minutesono.com
  4. ECCU ShoC 2018 powerpoint, Paul Atkinson, David Lewis
Continue Reading

Ultrasound guided hematoma block for distal radius fractures

Ultrasound guided hematoma block for distal radius fractures

Resident Clinical Pearl (RCP) September 2019

Robert Dunfield – PGY1 FMEM Dalhousie University, Saint John NB

Reviewed by Dr. Kavish Chandra

 

Mr. JG, a 34 year old male snowboarder, presents to your busy emergency department after a snowboarding accident. He suffered a fall onto his left outstretched hand after hitting a jump that was approximately one foot high. Radiograph shows a closed distal radius fracture with significant  dorsal angulation.

Figure courtesy of Dr Pir Abdul Ahad Aziz, Radiopaedia.org, rID: 47908

Tonight is a busy shift and you’re working in a resource-limited department with very few staff. In speaking with the patient, he’s nervous about the prospect of procedural sedation and would prefer to not be “put to sleep to fix [his] wrist”. Luckily, your department recently purchased an ultrasound machine and the patient consents to a hematoma block prior to reduction.


What is a hematoma?

Following the initial impact that causes a fracture, the initial stage of bone healing involves a hematoma formation. In simple terms, a hematoma is a large blood clot that collects at the fracture site. Hematomas are rich in vascular supply and are the site of eventual soft callus formation; they’re the result of bony blood supply being disrupted at the site of the defect

 

Stages in Fracture Repair. The healing of a bone fracture follows a series of progressive steps: (a) A fracture hematoma forms. (b) Internal and external calli form. (c) Cartilage of the calli is replaced by trabecular bone. (d) Remodeling occurs.1

 

Hematoma blocks as an alternative to procedural sedation?

Compared to procedural sedation, hematoma blocks can be done safely when procedural sedation is not an option or is contraindicated. They also offer an alternative option for analgesia when an emergency department is busy and resources are lacking to safely perform procedural sedation.2

  • Procedural sedation requires a period of recovery after the procedure, hematoma blocks do not necessitate traditional post procedural recovery.3
  • Evidence that suggests post-procedure analgesia is similar in hematoma block patients compared to patients who undergo procedural sedation.4
  • Hematoma blocks are a form of local anaesthesia that can be used when reducing simple, closed distal long bone fractures, like the distal radius fracture in this case. They can also be performed to provide analgesia for nondisplaced fractures.2

 

Prior to the advent of bedside ultrasound, hematoma blocks were dependent on external anatomy landmarking, using “step-off” site of the bony deformity as the landmark for injection. This can be difficult, however, in fractures where swelling, habitus, or deformity can distort the anatomy of the hematoma.2 This is where ultrasound plays a role in identifying the deformity and therefore improves the precision of hematoma injection.

Contraindications to hematoma block include allergy to the anaesthetic being used, if the fracture is open, if there is cellulitis overlying the site of the fracture, and/or if there is a neurovascular deficit on exam of the affected limb.5

 

Performing  a hematoma block under US guidance

Mr. JG requires reduction of his distal radius fracture. Due to his uneasiness with procedural sedation, combined with the busy and resource-strained nature of your emergency department, a hematoma block under ultrasound guidance is performed.

 

  • Gain informed consent: The initial step in performing a hematoma block is similar to all medical procedures in that the patient undergoing the procedure should be informed of the risks associated with hematoma blocks and fracture reduction. These include, although rare, compartment syndrome, local anesthetic toxicity, acute carpal tunnel syndrome, and temporary paralysis of the upper limb6. Remember that maximum dose of lidocaine without epinephrine is 5mg/kg.
  • Reassess the neurovascular integrity of the limb: Prior to injecting the hematoma block, ensure you have confirmed neurovascular integrity of that limb.
  • Grab the supplies you’ll need: The following list is limited to the supplies needed for your hematoma block and does not include the supplies needed for fracture reduction and casting.
    • Ultrasound machine with a linear transducer probe
    • Tegaderm transparent film
    • Sterile lubricating jelly
    • Sterile skin marker
    • Sterile gloves
    • Chlorhexidine swabs x 3
    • 16G Needle (for drawing up analgesia)
    • 20G or 22G Needle (for injecting analgesia)
    • 10mL syringe
    • 1% lidocaine (approximately 10mL)
  • Landmark the hematoma using point of care ultrasound: Trace the bone’s cortex on the dorsal aspect of the forearm from the proximal aspect of the fracture towards the fracture site until you reach an interruption in the cortex of the radius (see below). Mark that site with your marker for injection.

Left: Sagittal image of left radius outlining an interruption in the radial cortex at the site of the hematoma. Right: Same image, edited to identify anatomy.8 Edited by Robert Dunfield PGY1-Dalhousie

  • Clean the site and prepare other materials: Clean the site with chlorhexidine swabs x 3. Allow it to dry while you prepare the remainder of your equipment. Draw up your 10mL of 1% lidocaine with the 16G needle and then change the needle to your 20 or 22G needle. A longer needle may be needed to reach the site of the hematoma.
  • Prepare your transducer: Clean your linear transducer and then put on your sterile gloves. With the help of an assistant apply the sterile tegaderm film to the liner transducer and place sterile lubricating jelly on the probe.
  • Insert needle under US guidance: Using the probe to visualize the site of the hematoma, simultaneously begin to insert the needle in a caudal fashion toward the hematoma, visualizing the needle in the long axis. Use the ultrasound image to follow the needle’s insertion.

Injection of hematoma block under ultrasound guidance.6 Modified by Robert Dunfield PGY1-Dalhousie

  • Inject the lidocaine: Inject 10mL of 1% lidocaine into the hematoma.
  • Give time for analgesia to take effect: Allow 5 to 10 minutes of time to allow the analgesia to take full effect, then reassess neurovascular integrity.
  • Proceed with the reduction.
  • Added note: It’s possible for distal radius fractures to have an associated ulnar styloid fracture, which will require repeating the same steps as described above, only at the side of the ulnar fracture.

 

Summary:

    • Hematoma blocks under ultrasound guidance can be done on certain distal long bone fractures that lack any contraindications
    • Use the ultrasound probe to trace the bone’s cortex and identify the site of the hematoma, then insert the needle into the hematoma under the guidance of your linear transducer.
    • Confirm needle placement into the hematoma by aspiration and inject 10mL of 1% lidocaine into the hematoma.
    • Allow 5 to 10 minutes of analgesia onset before reducing the fracture.
    • Remember to reassess the limb’s neurovascular integrity before and after the procedure.

Copyedited by Kavish Chandra

 

Resources:

  1. Rice University. Anatomy and Physiology. Chapter 6.5: Bone Repair. https://opentextbc.ca/anatomyandphysiology/chapter/6-5-fractures-bone-repair. Accessed: September 03, 2019. Last updated: unknown.
  2. Gottlieb M and Cosby K. Ultrasound-guided hematoma block for distal radial and ulnar fractures. Journal of Emergency Medicine. 2015;48(3):310-312.
  3. Alerhand S and Koyfman A. Ultrasound-Guided Hematoma Block. emDocs.net. http://www.emdocs.net/ultrasound-guided-hematoma-block/. Accessed: September 07, 2019. Last updated: December 21, 2014.
  4. Fathi M, Moezzi M, Abbasi S, Farsi D, Zare MA, Hafezimoghadam P. Ultrasound-guided hematoma block in distal radial fracture reduction: a randomised clinical trial. Emerg Med J. 2015;32:474-477.
  5. Reichman EF. Emergency Medicine Procedures. Second Edition. 2013:Chapter 125 Hematoma Blocks.
  6. Emiley P, Schreier S, Pryor P. Hematoma Blocks for Reduction of Distal Radius Fractures. Emergency Physicians Monthly. https://epmonthly.com/article/hematoma-blocks-for-reduction-of-distal-radius-fractures/. Accessed: September 14, 2019. Last updated: February 2017.
  7. Beaty JH and Kasser JR. Rockwood and Wilkins’ Fractures in Children. Chapter 3: Pain Relief and Related Concerns in Children’s Fractures, pp61-63.
  8. EM Cases and POCUS Toronto. POCUS Cases 4: Distal Radius Fracture. https://emergencymedicinecases.com/video/pocus-cases-4-distal-radius-fracture/. Accessed: September 14, 2019. Last updated: July 2018.
Continue Reading

Lung Ultrasound in the Evaluation of Pleural Infection

Lung Ultrasound in the Evaluation of Pleural Infection

Resident Clinical Pearl (RCP) July 2019

Yazan Ghanem PGY5 Internal Medicine, Dalhousie University

SJRHEM PoCUS Elective

 

Reviewed and edited by  Dr. David Lewis.

 


CASE: MR. WHITE

 

83 year old male with known past medical history of mild cognitive impairment (lives alone in assisted living). Two weeks prior to current presentation, he was admitted with community acquired pneumonia and discharged after 2 nights of hospital stay on oral antibiotics.

He is now presenting with 5 days history of worsening dyspnea, fever, fatigue and reduced oral intake. Vital signs are: Temperature 38.4 C; heart rate 80/min; Blood pressure 121/67; Respiratory rate 28/ minute; Oxygen saturation 90% on room air. His chest exam showed reduced air entry and dullness to percussion in the right hemithorax.

CXR:

 

Bedside POCUS:

 

Pleural fluid analysis:

•       WBC – 22,000 cells per uL

•       LDH – 1256 Units / L

•       Glc – 2.2 mmol / L

•       pH – 7.18

•       Gram Stain – Neg

 

Next steps in management?

 

A – 14 Fr pleural drain + Start IV Levofloxacin

 

B – 28 Fr pleural drain + Start Ceftriaxone / Azithromycin

 

C – 14 Fr pleural drain + Start Piperacillin – Tazobactam

 

D – Start Ceftriaxone / Azithromycin + Repeat CXR in 1 week

 

 

(See end of page for answer )

 


 

Normal Thoracic Ultrasound:

Thoracic Ultrasound is limited by bony structures (ribs and scapulae) as well as by air within lungs (poor conductor of sound waves).

With the transducer held in the longitudinal plane:

1 –     Ribs are visualized as repeating curvilinear structures with a posterior acoustic shadow.

2 –     Overlying muscle and fascia are seen as linear shadows with soft tissue with soft tissue echogenicity.

3 –     Parietal and visceral pleura is visualized as a single echogenic line no more than 2 mm in width which “slides” or “glides” beneath the ribs with respiration. Two separate lines can be seen with a high frequency transducer.

4 –     Normal aerated lung blocks progression of sound waves and is characterized by haphazard snowstorm appearance caused by reverberation artifact.

5 –     Diaphragms are bright curvilinear structures which move with respiration. Liver and spleen have a characteristic appearance below the right and left hemi diaphragms respectively.

 

 


Pleural Effusion:

Ultrasound has higher sensitivity in detecting pleural effusions than clinical examination and chest X-Ray.

On Ultrasound, pleural effusions appear as an anechoic or hypoechoic area between the visceral and parietal pleura that changes in shape with respiration. Atelectatic lung tissue appear in the far field as flapping or swaying “tongue-like” echodensities.

Ultrasound morphology:

1-     Anechoic Effusion: Totally echo-free (Could be transudative or exudative)

2-     Complex Non-septated: Echogenic appearing densities present (fibrinous debris). Always exudative.

3-     Complex Septated: Septa appear in fluid. Always exudative.

 

 


Parapneumonic Effusions and Empyema:

Ultrasound is superior to CT in demonstrating septae in the pleural space. However, CT is recommended for evaluation of complex pleuro-parenchymal disease and loculated pleural collections if drainage is planned: There is no correlation between ultrasound appearance and the presence of pus or need for surgical drainage; however, the presence of a septated appearing parapneumonic effusion correlate with poorer outcomes (longer hospital stay, longer chest tube drainage, higher likelihood for need for fibrinolytic therapy and surgical intervention.

Parapneumonic effusions appear as hyperechoic (with or without septae) on ultrasound.

 


Pulmonary Consolidation:

Pulmonary consolidation is sonographically visible in the presence of a pleural effusion that acts as an acoustic window or if directly abutting the pleura.

It appears as a wedge-shaped irregular echogenic area with air or fluid bronchograms.

 


 

Back to Mr. White

 

Next steps in management?

 

A – 14 Fr pleural drain + Start IV Levofloxacin

 

B – 28 Fr pleural drain + Start Ceftriaxone / Azithromycin

 

C –14 Fr pleural drain + Start Pipercillin- Tazobactam

 

D – Start Ceftriaxone / Azithromycin + Repeat CXR in 1 week

 

Rationale:

Complicated parapneumonic effusions should be managed with drainage and antibiotics that will treat anaerobic infection. An alternative would be a combination of Ceftriaxone and Metronidazole (No pseudomonas coverage). Levofloxacin alone does not add any anaerobic coverage. Azithromycin has poor penetration into loculated pleural collections.

 


 References

 

British Thoracic Society – Pleural Disease Guideline – 2010

https://thorax.bmj.com/content/65/8/667

 

Continue Reading

Fall ECCU Fest 2018 – PoCUS Conference Workshop and ECCU2 Course

September 27th – 28th 2018

The Algonquin Resort in St. Andrews by-the-Sea, New Brunswick, Canada

Atlantic Canada’s top PoCUS event

UPDATE

 

Now open for applications/booking – Only a few places still available

 

The ECCU Conference is being held in conjunction with the ECCU2 Advanced Applications Course in order to provide those attending the course and other delegates with an opportunity to access an update in the hottest clinical PoCUS topics. The focus will be on presenting the best emerging evidence, strategies for developing a local PoCUS program and developing competencies.

Includes:

  • International PoCUS experts
  • Clinical PoCUS hot topics and updates
  • Top PoCUS research
  • IP2 Diagnostic stream lectures

Conference delegates will have access to the Diagnostic stream lectures of the ECCU2 Advanced Applications Course, which will include an Gallbladder, Renal, DVT and Ocular

Invited Faculty – 2018

Dr. Hein Lamprecht – South Africa – (ECCU Fest 2018) – PoCUS Educator Extraordinaire – IFEM – WinFocus

Dr. Peter Croft – USA – (ECCU Fest 2018) – New England PoCUS disrupter –past MGH PoCUS Fellow

Dr. David Mackenzie – USA – (ECCU Fest 2018) – Canadian New Englander, PoCUS innovator – past MGH PoCUS Fellow

 

Also our top Dalhousie Faculty of PoCUS Experts

 


 

Open for applications and booking: More Information Here

 

There are only 2 places left on the 2 day Advanced Apps ECCU 2 course, however we still have good availability for the 1 day conference workshop

Continue Reading

Regional anesthesia of the hand

Regional anesthesia of the hand: ultrasound-guided vs tumescent anesthesia

Resident Clinical Pearl (RCP) – February 2018

Sean Hurley Emergency Medicine PGY1 (FRCPC), Dalhousie University, Halifax, Nova Scotia

Reviewed by Dr. David Lewis

 

The goal of this resident clinical pearl is to discuss two different methods of achieving complete anesthesia of the hand. Hopefully, by the end of this article, you will have the knowledge to perform both methods in the emergency department. The first method is ultrasound (US)-guided nerve blocks of the ulnar, median, and radial nerves. The second method is the “tumescent anaesthesia” approach used by many hand surgeons around the world for wide-awake hand surgery, including local, local anesthetic guru and plastic surgeon, Dr. Donald Lalonde who provided many of the clinical pearls in this article.

 

Method 1:  Ultrasound-guided nerve block

In a recent article by Amini et al. (2016), 84% of 121 emergency medicine residency programs surveyed in the United States reported that US-guided nerve blocks are performed at their institution. Of the 16 different nerve blocks reported, forearm blocks were the most commonly performed (74%) (Table 1). The main indications for nerve blocks are outlined in Table 2 1.

Table 1 and 2 from Amini et al., 2016 1

 

Three major nerves, median, ulnar, and radial, provide sensory innervation of the hand (Figure 1). Each nerve needs to be blocked in a simple straightforward approach, which was shown to to be quick, safe and effective. After a 1-hour training session, residents, fellows, and staff emergency physicians had 100% success rate with no rescue anesthesia on 11 hand pathology patients presenting to the ED. The blocks were performed in a median time of 9 minutes with no complications 2.

 

Figure 1. Cutaenous innervation of the hand. https://www.nysora.com/wrist-block

 

Figure 2. Indications for different nerve blocks of the hand http://highlandultrasound.com/forearm-blocks/

 

Radial Nerve: Palpate the radial artery in the volar aspect of distal forearm then place the US probe over the artery in a transverse orientation. Move the probe proximally until you clearly identify the radial nerve (Figure 3), which is located at the radial aspect of the radial artery. Insert your needle using an in-line approach (Figure 4). Inject 5-10cc of 1% lidocaine with epinephrine until you can clearly see the nerve bathed in lidocaine.

Pearl: The radial nerve is often difficult to visualize in the forearm. The radial nerve is more easily visualized above the elbow along the spiral groove of the humerus. Place the probe in a transverse orientation along the lateral aspect of the humerus between the brachioradialis and brachialis muscles. This block is more proximal and will require longer time to peak anesthesia.

 

Ulnar nerve: Use the exact same 2-step approach but on the ulnar side of the forearm. The ulnar nerve is located at the ulnar aspect of the ulnar artery (Figure 3).

 

Median nerve: The median nerve lies between the palmaris longus and the flexor carpi radialis. Position the probe in the transverse plane over this location. Insert your needle from either side using an in-plane or out-of-plane approach

 

Pearl: the median nerve and the many tendons of the distal forearm can be difficult to distinguish. You can identify the nerve by tilting the probe, which causes the tendons to disappear, as the US waves are no longer reflected back to probe, while the median nerve fibers still reflect waves back to the probe. Alternatively, you can slide the probe proximally where the tendons transition to muscle fibers, allowing the median nerve to be easily distinguishable.

Pearl: The palmar cutaneous branch of the median nerve that supplies the thenar eminence branches off before the carpal tunnel. Make sure you move the probe proximally before blocking the nerve so you don’t miss this important sensory branch.

Pearl: The more local anesthetic, the better! Some resources recommend 3-5cc of 1% lidocaine per nerve. Why not use 10cc or more for each nerve? You will still be safely under 7mg/kg limit.

 

Figure 3. Ultrasound identification of the ulnar nerve (left), median nerve (middle), and radial nerve (right). (Figure from Liebemann et al, 2006) 2.

 

Figure 4. Ultrasound guided ulnar nerve block using an in-plane technique (Figure from Sohoni et al., 2016) 3.

 

Please see link to excellent descriptions and videos of ulnar, radial, and median US-guided nerve blocks in the ED. www.highlandultrasound.com/forearm-blocks/

 

Method 2: Tumescent anesthesia

Tumescent means “Swollen”. In relation to local anaesthesia, Dr. Lalonde provides the following definition in his textbook Wide-Awake Hand Surgery: “Injecting a large enough volume of local anesthetic that you can see it plump up the skin and feel its slightly firm consistency with your finger through the skin” 4. The tumescent anesthesia approach has been described in depth for a variety of hand surgeries 4-6.

Using a 10cc syringe, aim for the space directly between the median and ulnar nerve (figure 5 and Video 1).  As you puncture the skin, Inject 3-5cc in the subcutaneous space. This is critical to block superficial nerves in this region, including the palmar cutaneous branch of the median nerve. Then, move your needle >3-4mm deeper through the superficial fascia in the forearm compartment where the median and ulnar nerves reside. Inject the remainder of your 10cc syringe into this space. With a single poke, the ulnar and median nerve distributions should be completely anesthetized.

Now, all that remain are the superficial branches of radial nerves and the posterior interosseus nerve. The superficial branches of radial nerve lie over the anatomical snuffbox. Insert your needle within 1cm of your previously anesthetized skin and blow local anesthesia into the subcutaneous space as you slowly move your needle towards the radial aspect of the wrist until you have a tumescent area of local anesthesia over the snuffbox. For the PIN, which is primarily a motor branch of radial nerve but has some sensory contribution, palpate the distal radial ulnar joint  of the dorsal aspect of the wrist. The PIN runs along the interosseous membrane so the needle needs to pass through the deep fascia of the forearm. Inject another 5cc of lidocaine in this location.

 

Figure 5. Tumescent anesthesia of the median and ulnar nerve 5.

 

Video 1. Tumescent anesthesia of the hand (courtesy of S. Hurley).

 

Which approach is better?

No studies have directly compared the two approaches discussed in this article. A recent Cochrane review article reviewed compared US-guided vs. anatomical landmark technique vs. trans-arterial vs. peripheral nerve stimulation for lower and upper limb blocks by trained anaesthetists. They found US-guided had greater success rates, less conversions to general anesthetic, lower rates of parathesias and vascular puncture 7.

A recent small randomized control trial compared US-guided nerve blocks of the forearm to anatomical landmark-based technique and found 14 of 18 ultrasound-guided forearm blocks were successful, as opposed to 10 of 18 for the anatomical technique 3.

Pearl: The tumescent anesthesia technique blocks both smaller and larger nerves of the hand and will likely achieve faster anesthesia compared to nerve blocks of the ulnar, median, and radial nerve.  Expect up to an hour for the large nerve blocks to take full effect.

 

Conclusions

Both methods, US-Guided nerve blocks and tumescent anesthesia are safe, effective, and relatively easy options to achieve complete anesthesia of the hand. For both techniques, remember basic principles for minimizing pain during injection of local anaesthesia to optimize patient comfort and satisfaction 4-6.

 

References

  1. Amini R, Kartchner JZ, Nagdev A, Adhikari S. 2016. Ultrasound‐Guided nerve blocks in emergency medicine practice. Journal of Ultrasound in Medicine 35: 731-736.
  2. Liebmann O, Price D, Mills C, et al. 2006. Feasibility of forearm ultrasonography-guided nerve blocks of the radial, ulnar, and median nerves for hand procedures in the emergency department. Ann Emerg Med 48: 558-562.
  3. Sohoni A, Nagdev A, Takhar S, Stone M. 2016. Forearm ultrasound-guided nerve blocks vs landmark-based wrist blocks for hand anesthesia in healthy volunteers. Am J Emerg Med 34: 730-734.
  4. Lalonde D. 2016. Wide awake hand surgery, CRC Press, Taylor & Francis Group. Boca Raton, FL.
  5. Lalonde DH. 2010. “Hole-in-one” local anesthesia for wide-awake carpal tunnel surgery. Plast Reconstr Surg 126: 1642-1644.
  6. Farhangkhoee H, Lalonde J, Lalonde DH. 2012. Teaching medical students and residents how to inject local anesthesia almost painlessly. Can J Plast Surg 20: 169-172.
  7. Lewis SR, Price A, Walker KJ, McGrattan K, Smith AF. 2015. Ultrasound guidance for upper and lower limb blocks. The Cochrane Library.

 

This post was copyedited by Kavish Chandra @kavishpchandra

Continue Reading

New – Dal SJRHEM PoCUS Fellowship/Elective

The Dalhousie University (DU) Emergency Point of Care Ultrasound Elective and Fellowship Program at Saint John Regional Hospital (SJRH) with an optional up to 1 month placement in Pediatric PoCUS at the IWK Health Centre Pediatric Emergency Department

 

There are four primary components to the mini-fellowship and fellowship programs:

 

  1. Clinical: optimizing image acquisition and interpretation skills for both core and advanced emergency and point of care ultrasound applications
  2. Education: developing lecturing and teaching skills by developing an emergency ultrasound lecture portfolio and contributing to the program’s educational mission. Acquiring expertise at bedside ultrasound teaching and assessment.
  3. Administration: understanding the critical components required to run an emergency ultrasound program, set up and deliver educational events/courses and how to best utilize information technologies for image archiving, database management, and quality assurance.
  4. Research: understanding the state of emergency ultrasound research by participating in ultrasound journal club activities and developing an independent research project from its inception to publication.

 

For more information click here

Continue Reading

Suprapubic Aspiration PoCUS

Suprapubic aspiration – when the catheter doesn’t cut it.

Resident Clinical Pearl (RCP) – Guest Resident Edition

Sean Davis MD, PGY2 Family Medicine

Dalhousie University, Yarmouth, Nova Scotia

Reviewed and Edited by Dr. David Lewis

 

Urine is routinely analyzed and cultured as part of a sick child workup, as diagnosis of urinary tract infection can be difficult in pre-verbal children. They are unable to “point where it hurts”, and physical exam can be both difficult and unreliable in an irritable or obtunded infant. Urine may be collected in three ways – by “clean catch” collection, transurethral catheterization (TUC), and suprapubic aspiration (SPA). Given the inherent risk of contamination with local flora (over 25% in one cohort study)1, clean catch urine is typically useful only for ruling out UTI. TUC is more commonly performed as it does not require physician participation, but SPA remains a valid option for obtaining a urine sample for analysis and culture in children under the age of 2. It has been shown to have a significantly lower rate of contamination than TUC (1% versus 12%, respectively)1, although failure rates are higher with SPA4. Use of portable ultrasound has been shown to significantly increase the rate of success of SPA (79% US guided vs 52% blind)5.

 

RCP – The pee or not the pee: so many questions!

 

Indications:2,3

  • Labial adhesions/edema
  • Phimosis
  • Diarrhea
  • Unsuccessful urethral catheterization
  • Urethral/introital surgery
  • Urethral stricture
  • Urethral trauma
  • Urinary retention
  • Urinalysis/culture in children younger than 2 years
  • Chronic urethral/periurethral gland infection

Contraindications: 2,3

  • Genitourinary abnormalities (congenital or acquired)
  • Empty or unidentifiable bladder
  • Bladder tumor
  • Lower abdominal scarring
  • Overlying infection
  • Bleeding disorders
  • Organomegaly

Complications: 2,3

  • Gross hematuria
  • Abdominal wall cellulitis
  • Bowel perforation

Equipment: 2,3

  • Lidocaine for local anesthesia (1% or 2%, with or without epinephrine)
  • Adhesive bandaid
  • Povidone-iodine or Chlorhexidine prep
  • 25g to 27g 1” needle
  • 22g or 23g 1.5” needle
  • Sterile 5ml and 10ml syringes

Procedure (ultrasound-guided): 2,3

  • Position the patient supine in frog-leg position, using parent or caregiver to assist with immobilization.
  • Using sterile technique, identify the bladder on ultrasound; it appears as an anechoic ovoid structure just below the abdominal musculature.
    • Landmarking: midline lower abdomen, just above the pubic symphysis
  • Mark the area and sterilize; infiltrate local anesthetic into the marked area
  • Insert the needle slightly cephalad, 10-20° off perpendicular while aspirating until urine appears.
  • If the insertion is unsuccessful, do not withdraw the needle fully. Instead, pull back until the needle tip rests in the subcutaneous tissue and then redirect 10° in either direction. Do not attempt more than 3 times.
  • One sufficient urine is obtained, withdraw the needle and place a sterile dressing at the site of the insertion.

 

 

From: Performing Medical Procedures – NEJM

 

References

    1. Contamination rates of different urine collection methods for the diagnosis of urinary tract infections in young children: an observational cohort study. Tosif S; Baker A; Oakley E; Donath S; Babl FE. J Paediatr Child Health. 2012; 48(8):659-64 (ISSN: 1440-1754). Retrieved from https://reference.medscape.com/medline/abstract/22537082 on December 10, 2017
    2. Suprapubic Aspiration. Alexander D Tapper, MD, Chirag Dave, MD, Adam J Rosh, MD, Syed Mohammad Akbar Jafri, MD. Medscape. Updated: Mar 31, 2017. Retrieved from https://emedicine.medscape.com/article/82964-overview#a4 on December 10, 2017
    3. Suprapubic Bladder Aspiration. Jennifer R. Marin, M.D., Nader Shaikh, M.D., Steven G. Docimo, M.D., Robert W. Hickey, M.D., and Alejandro Hoberman, M.D. N Engl J Med 2014; 371:e13September 4, 2014DOI: 10.1056/NEJMvcm1209888. Retrieved from http://www.nejm.org/doi/full/10.1056/NEJMvcm1209888 on December 10, 2017
    4. Suprapubic bladder aspiration versus urethral catheterization in ill infants: success, efficiency and complication rates. Pollack CV Jr, Pollack ES, Andrew ME. Ann Emerg Med. 1994 Feb;23(2):225-30. Retrieved December 10, 2017.
    5. Use of portable ultrasound to assist urine collection by suprapubic aspiration. Gochman RF1, Karasic RB, Heller MB. Ann Emerg Med. 1991 Jun;20(6):631-5. Retrieved December 10, 2017.

 

Other PEM PoCUS Videos Here

 

 

Continue Reading

What we missed in FOAM October 2017

Welcome to SJRHEM’s newest feature, “Best of FOAM”. This is a quick curated list of the best free open access medical education the internet has to offer!

Subscribe to our twitter feed for regular updates and enjoy!

 

EM procedures

 

Clinical summaries

 

Kavish Chandra, R3 FMEM, Dalhousie University, Saint John, New Brunswick

 

Continue Reading

What we missed in FOAM Sept 2017

 

Welcome to SJRHEM’s newest feature, “Best of FOAM”. This is a quick curated list of the best free open access medical education the internet has to offer!

Subscribe to our twitter feed for regular updates and enjoy!

 

EM procedures

Clinical tools

 

Clinical summaries

 

Kavish Chandra, R3 FMEM, Dalhousie University, Saint John, New Brunswick

 

 

Continue Reading