EM Reflections – June 2020

Thanks to Dr Joanna Middleton for leading the discussions this month

Edited by Dr David Lewis 


Discussion Topics

  1. Antiviral Toxicity

    • Always adjust dosing in patients with renal impairment
  2. Necrotising Fasciitis

    • Difficult clinical diagnosis
    • Should be on the differential for all soft tissue infections
    • Delayed definitive care always results in poor outcomes
  3. Epidural Abscess

    • Thorough detailed neurological examination required
    • Isolated leg weakness is rare in Stroke
    • Progressive development of symproms and mixed UMN/LMN signs suggests spinal cord compression.

 


Antiviral Toxicity

Case

A 70yr old male presents with a typical zoster rash in the left L1 dermatome. He has a past medical history of chronic renal insufficiency. He is started on Valacyclovir 1000mg TID. He represents 3 days later with hallucinations including a feeling that he was occupying a dead body. What is the differential diagnosis?


 

Varicella Zoster Encephalitis vs Valacyclovir Toxicity

VZV and antiviral toxicity can present with similar symptoms

Two main risk factors increase the risk for VZV

  • age greater than 50 years old
  • immunocompromised due to reduced T cell-mediated immunity

The main risk factor for antiviral toxicity is renal insufficiency

Differentiation

  • Timing
    • Toxicity presents within 1-3 days of starting drug (vs 1-2 weeks)

 

  • Symptoms – both can present with confusion and altered LOC
    • Encephalitis – fever, HA, seizures, more likely with Trigeminal nerve (V1) or disseminated zoster
    • Toxicity – Visual hallucinations, dysphasia, tremor/myoclonus
    • Toxicity – Cotard’s syndrome…

Cotard’s Syndrome

“le délire des négations”

(delirium of negation)

https://en.wikipedia.org/wiki/Cotard_delusion

  • Described in 1880 by neurologist Jules Cotard
    • “patient usually denies their own existence, the existence of a certain body part, or the existence of a portion of their body”
  • Seen in schizophrenia, psychosis and…
  • ….acyclovir toxicity (felt to be due to metabolite CMMB (9-carboxymethoxymethylguanine) crossing BBB)

Further Reading

Varicella Zoster Encephalitis case report and outline

Valacyclovir Toxicity case report and outline

Cotard’s Syndrome

Drug Dosing in Chronic Kidney Disease

 

 

 


Necrotising Soft Tissue Infections (NSTI)

Case

A 28yr old female presents pain, redness and swelling over the right thigh. She has a past medical history of type 2 diabetes. She is managed as an outpatient with intravenous ceftriaxone q24hrs. Her symptoms failed to respond on follow up. What is the concern now? Are there any red flags? What condition needs to be considered in patients with soft tissue infections that fail to respond to antibiotics?


NSTI first described by Hippocrates 5th century BC

“[m]any were attacked by the erysipelas all over the body when the exciting cause was a trivial accident…flesh, sinews, and bones fell away in large quantities…there were many deaths.”

 

Necrotizing fasciitis is characterized by rapid destruction of tissue, systemic toxicity, and, if not treated aggressively, gross morbidity and mortality. Early diagnosis and aggressive surgical treatment reduces risk; however, it is often difficult to diagnose NF, and sometimes patients are treated for simple cellulitis until they rapidly deteriorate.

Infection typically spreads along the muscle fascia due to its relatively poor blood supply; muscle tissue is initially spared because of its generous blood supply.

Infection requires inoculation of the pathogen into the subcutaneous tissue or via hematogenous spread.

Classification

  • Type 1 – polymicrobial – older/diabetics/EtOH/IC/PVD
  • Type 2 – monomicrobial – usually group A beta-hemolytic strep (often hematogenous) – healthy people of all ages

Early signs and symptoms of NSTI are often identical to those seen with cellulitis or abscesses potentially making the correct diagnosis difficult

‘Classic’ Signs / Symptoms

(1) the presence of bullae
(2) skin ecchymosis that precedes skin necrosis
(3) crepitus
(4) cutaneous anesthesia
(5) pain out of proportion to examination
(6) edema that extends beyond the skin erythema
(7) systemic toxicity
(8) progression of infection despite antibiotic therapy or rapid progression

First 4 are “hard” signs

  • Erythema (without sharp margins; 72 percent)
  • Edema that extends beyond the visible erythema (75 percent)
  • Severe pain (out of proportion to exam findings in some cases; 72 percent)
  • Fever (60 percent)
  • Crepitus (50 percent)
  • Skin bullae, necrosis, or ecchymosis (38 percent)

Streaking lymphangitis favours the diagnosis of cellulitis over necrotizing fasciitis

Diagnosis

  • There is no set of clinical findings, lab test results and even imaging that can definitively rule out necrotizing fasciitis
    • “Surgical exploration is the only way to establish the diagnosis of necrotizing infection”.
    • “Surgical exploration should not be delayed when there is clinical suspicion for a necrotizing infection while awaiting results of radiographic imaging other diagnostic information”
  • But what if you really aren’t sure?  Or if you get pushback?
  • CT is probably the best test – esp Type 1 (gas forming)
    • Findings – gas, fluid collections, tissue enhancement, inflammatory fascial changes
  • Finger test…
    • “After local anesthesia, make a 2-3 cm incision in the skin large enough to insert your index finger down to the deep fascia. Lack of bleeding and/or “dishwater pus” in the wound are very suggestive of NSTI. Gently probe the tissues with your finger down to the deep fascia. If the deep tissues dissect easily with minimal resistance, the finger test is + and NSTI can be ruled in.”  (emergencymedicinecases.com)
  • But what about PoCUS????

PoCUS

Diagnosis of Necrotizing Faciitis with Bedside Ultrasound: the STAFF Exam

Findings – “STAFF”

ST – subcutaneous thickening
A – air
FF – fascial fluid

Ultrasound video demonstrating Subcutaneous Thickening, Air, and Fascial Fluid (STAFF).

 

Soft tissue ultrasound findings are significantly different when compared to normal soft tissue ultrasound

Bottom Line: Limited data, but basically PoCUS is not sufficient to rule-in or rule out, but might be helpful in raising suspicion level for necrotising fasciitis for physicians who routinely scan all soft tissue infections.

 

LRINF Score

The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) Score: A Tool for Distinguishing Necrotizing Fasciitis From Other Soft Tissue Infections

Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) Score.  2004, retrospective – score >6 negative predictive value of 96.0% and a positive predictive value of 92%.

 

A validation study looking only at patients with pathology-confirmed necrotizing fasciitis showed that a LRINEC score cutoff of 6 points for necrotizing fasciitis only had a sensitivity of 59.2% and a specificity of 83.8%, yielding a PPV of 37.9% and NPV of 92.5%. However, the study did show that severe cellulitis had a LRINEC Sscore ≥ 6 points only 16.2% of the time.  Therefore, the available evidence suggests that the LRINEC score should not be used to rule-out NSTI.

Bottom Line: Doesn’t rule-out…… or rule-in

 

Suggested Algorithm – UpToDate

 

EM Cases Review

BCE 69 Necrotizing Fasciitis

 

Further Reading

Necrotizing fasciitis – Can Fam Physician. 2009 Oct; 55(10): 981–987.

 


Epidural Abscess

Case

A 40yr old female presents with left leg weakness. She has a complex recent past medical history including recently diagnosed pneumonia, previous renal colic and type 2 diabetes. Could this be a stroke? What are the other causes of leg weakness? How does the examination differentiate UMN from LMN lesions? When considering a diagnosis of epidural abscess what investigation is required? How soon should it be performed?


Only 4% of Strokes present with isolated or predominant leg weakness. (Brain. 1994 Apr;117 ( Pt 2):347-54.
doi: 10.1093/brain/117.2.347)

Common mechanisms of weakness:

  • Upper motor neuron lesions (Stroke, Tumour, Spinal Cord Compression, etc)
  • Lower motor neuron lesions ( Neuropathy, Disc Prolapse, Spinal Cord Compression, etc)
  • Neuromuscular junction lesions (Myasthenia, etc)
  • Neuropathies (Guillain-Barre, etc)
  • Muscle (Myopathies, etc)

Full review on Muscle Weakness from the Merck Manual here

Weakness that becomes severe within minutes or less is usually caused by severe trauma or stroke; in stroke, weakness is usually unilateral and can be mild or severe. Sudden weakness, numbness, and severe pain localized to a limb are more likely caused by local arterial occlusion and limb ischemia, which can be differentiated by vascular assessment (eg, pulse, color, temperature, capillary refill, differences in Doppler-measured limb BPs). Spinal cord compression can also cause paralysis that evolves over minutes (but usually over hours or days) and is readily distinguished by incontinence and clinical findings of a discrete cord sensory and motor level.

Unilateral upper motor neuron signs (spasticity, hyperreflexia, extensor plantar response) and weakness involving an arm and a leg on the same side of the body: A contralateral hemispheric lesion, most often a stroke

Upper or lower motor neuron signs (or both) plus loss of sensation below a segmental spinal cord level and loss of bowel or bladder control (or both): A spinal cord lesion

 

Epidural Abscess

Spinal epidural abscess (SEA) is a severe pyogenic infection of the epidural space that leads to devastating neurological deficits and may be fatal. SEA is usually located in the thoracic and lumbar parts of the vertebral column and injures the spine by direct compression or local ischemia. Spinal injury may be prevented if surgical and medical interventions are implemented early. The diagnosis is difficult, because clinical symptoms are not specific and can mimic many benign conditions. The classical triad of symptoms includes back pain, fever and neurological deterioration.

Spinal Epidural Abscess: Common Symptoms of an Emergency Condition – A Case Report

 

  • 75% are a delayed diagnosis
    • Usually hematogenous spread, usually S. aureus
  • Diagnosis
    • CRP has an sensitivity of 85%, specificity of 50%
    • MRI is gold standard
    • CT with contrast 2nd choice

 

Further Reading

Spinal epidural abscess

Episode 26: Low Back Pain Emergencies

 

 

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Lung PoCUS – Podcast

Lung PoCUS in Pediatric Emergency Medicine – Podcast

PoCUS Fellowship Clinical Pearl (RCP) May 2020

Dr. Mandy Peach (Emergency Physician and Dalhousie PoCUS Fellow, Saint John, NB, Canada)

Reviewed by Dr. David Lewis

 


Extract:

“My name is Mandy Peach and I am Emergency Physician at the Saint John Regional Hospital in Saint John, New Brunswick. I’m currently completing a PoCUS Fellowship and a pediatric rotation through the IWK Emergency Department in Halifax…….

What is the evidence for the use of PoCUS and diagnosing pediatric pneumonia. Well trained PoCUS Physicians can identify pneumonia with a sensitivity of 89% and a specificity of 94%, compared community-acquired pneumonia chest x-ray has a sensitivity of 69% and a specificity of 100%, if you see it great…. but what about early bacterial pneumonia and this case PoCUS has the upper hand, and if you consider consolidations behind the heart that can be visualized on PoCUS and obscured on chest x-ray – PoCUS 2  chest x-ray zero. So clearly it’s a useful tool to have when trying to differentiate between bacterial pneumonia that requires treatment and viral causes that would indicate conservative management. So how do we actually ultrasound the lungs…..the first step is to make the kid comfortable scan them in a position of comfort for example and their parents arms what the patient touch the ultrasound gel or the probe so it’s less of a scary thing maybe play their favourite music or YouTube video on the background or give them their favourite or snack do you want to choose a high frequency linear probe and scanning the longitudinal plane ……….”

 

Listen to the Podcast for some useful tips on performing and interpreting lung ultrasound in the pediatric population.

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Deep Dive Lung PoCUS – COVID 19 Pandemic

SJRHEM Weekly COVID-19 Rounds – May 2020

Dr. David Lewis


 

 

Part One covers aspects of core and advanced aspects of lung ultrasound application including: Zones, Technique, and Artifacts

Part Two covers PoCUS in COVID, the recent research, PoCUS findings, Infection Protection and Control, Indications and Pathways.


Part 1

 


Part 2

 

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Whose Line is it Anyway? – PoCUS in a Patient with Dyspnea

Medical Student Clinical Pearl – March 2020

Nguyet (Na) Nguyen

MD Class of 2021
Memorial University of Newfoundland

Reviewed and Edited by Dr. David Lewis

All case histories are illustrative and not based on any individual


 

Case Report

ID: 60 y/o M with dyspnea presenting to the ED late evening

HPI: Patient complained of increasing SOB starting the morning on day of presentation, with a worsening 3 days of non-productive cough. No chest pain or other cardiac features. No complaint suggestive of URTI or GI illness. Patient was given Atrovent and Ventolin en route by EMS, and was allegedly moving more air into his lungs after this intervention. Patient reports no ankle swelling, paroxysmal nocturnal dyspnea, but reports using 2 pillows to elevate himself when sleeping. Patient reports no fever, unexplained weight loss or fatigue.

Past medical history includes chronic back pain, DM, atrial fibrillation, peripheral DM-related ulcers, chronic kidney disease, BPH, colon cancer with hepatic metastases. Past surgical history significant for 5x CABG, liver and colon resection.

His medications are amitriptyline 10mg PO qhs, acetaminophen 650mg PO BID, dutasteride 0.5mg PO daily, ferrous sulfate 300mg PO daily, furosemide 40mg PO BID, metformin 500mg BID, pantoprazole 40mg PO BID, pregabalin 150mg PO BID, primidone 125mg PO daily, rosuvastatin 40mg PO qhs, rivaroxaban 15mg PO daily.

He has a distant 10 pack-years smoking history, drinks alcohol occasionally, and does not use recreational drugs. The patient lives with his wife in their own home.

Physical exam: Patient was markedly pale, non-diaphoretic, in tripod position with increased work of breathing. His temperature was 36.9, regular pulse rate at 105, respiratory rate 22, oxygen saturation 90% on room air and a nebulizer mask through which he was receiving aerosolized Atrovent and Ventolin. His BP was 125/78mmHg.

Cardiovascular exam revealed distant S1S2 in a chest with no visible deformity. His JVD was at the level of the sternal angle, there was no pedal edema bilateral. Capillary refill was 3 seconds bilateral at the thumbs. Percussion revealed no focal dullness, however on auscultation, basal crackles were heard more prominently in the right lung base, though also present on the left. There were also wheezes noted in the upper lobes heard in the anterior chest. Abdomen was soft, non-distended, non-tender. Neurological exam unremarkable.

Investigations: ECG showed sinus tachycardia with a LBBB, bloods drawn for routine labs, VBG, lactate, CXR ordered.

Differential diagnosis: AECOPD vs congestive heart failure.

PoCUS (Arrival Time + 10 mins): B-lines were observed in both lungs when a curvilinear probe was placed over different areas of the anterior chest. A small pleural effusion was also noted at the bottom of the right lung. B-lines represent increased fluid in an area of the lung, and given different clinical contexts maye represent pulmonary edema, pneumonia, or pulmonary contusion. In this case the most likely explanation for bilateral diffuse B-Lines is CHF and Pulmonary Edema. 

Working Diagnosis (Arrival Time + 10 mins): CHF and Pulmonary Edema

Management (Arrival Time + 15 mins): Pending transfer fo CXR and results of investigations the patient was treated with intravenous diuretics. He passed 500mls of urine and his symptoms improved considerably.

 

Investigations Results (Arrival Time + 45 mins): leukocytes 6.4, hemoglobin 83, platelet 165, sodium 140, potassium 5/0, chloride 101, creatinine 120, urea 11.7, glucose 17.0. Venous blood gas showed pH 7.31, pCO2 555, HCO3- 28 and lactate 2.7.

CXR (Arrival Time + 45 mins):

CXR was similar to above, this image is from: https://radiopaedia.org/cases/acute-pulmonary-oedema-6

 

Final impression: Congestive heart failure


What are B Lines?

These are the ultrasound equivalent of Kerley-B lines often reported on chest X-ray, which indicate edema in the lungs. For an exam to be positive (i.e indicative of pathology), one needs to see a minimum of 3 B-lines per view. B-lines look like flashlight beams traveling undisrupted down the entire ultrasound screen, as seen in the images above obtained during the exam.

These need to be distinguished from other artifacts such as ‘A-lines’ and ‘comet tails’. A-lines are seen in normal lungs. These are ‘repetitive reverberation’ artifacts of the normal pleura in motion. (Figure 1)(1)

‘Comet tails’- reported first by Lichenstein et al. in 1998 (although he was describing B-Lines in this paper) (Figure 2) (1), are ‘short, hypoechoic artifacts’ that only descend vertically partially down the screen. These are normal lung artifacts. This paper explains “a common misunderstanding in lung ultrasound” nomenclature that stems from Lichtenstein’s original paper.

Download pdf

 

From: https://www.mdedge.com/emergencymedicine/article/96697/imaging/emergency- ultrasound-lung-assessment

 


More on Comet Tails Artifact in this post from LitFL:

Comet tail artefact

 


 

Protocols

There are multiple protocols that guide the ultrasound technique (4) , some of which are:

  • Lichenstein et al (1998): longitudinal scans of anterior and lateral chest walls of patients in semi- recumbent position. Positive test defined as bilateral multiple B-lines diffuse anterolateral or lateral. The protocol had reported sensitivity (true positive) of 100%, and specificity (true negative) 92% for cardiogenic pulmonary edema. Blue Protocol (2015)
  • Liteplo et al (2008): anterior and lateral chest walls with patient supine: each chest divided into 4 zones (anterior, lateral, upper and lower). Positive test: pathologic pattern found in >1 zone on each side, with both sides involved.
  • Volpicelli et al. (2008): longitudinal scans of supine patients with chest divided into 11 areas (3 anterior R, 3 lateral R, 2 anterior L, 3 lateral L) to obtain score 0-11. Scores strongly correlated with radiologic and BNP (lab marker of CHF) at presentation.

 

 


 

What is the Evidence?

Al Deeb et al. conducted a systematic review and analysis of prospective cohort and prospective case-control studies in the ED, IDU, inpatient wards and prehospital settings (n = 1075). This was published in Acad Emerg Med (2014), which reported a sensitivity of 94.1% for using B-lines to diagnosis acute cardiogenic pulmonary edema (ACPE), and a specificity of 92.4% for patients with a moderate- high pretest probability for ACPE.

The SIMEU Multicenter study reported in 2015 reported a significantly higher accuracy (97% sensitivity and 97.4% specificity) with an approach incorporating lung ultrasound (LUS) in differentiating acute decompensated heart failure (ADHF) and non-cardiac causes of acute dyspnea, compared to approaches using the initial clinical workup (past medical history, history of presenting illness, physical examination, ECG, ABG), chest X-ray alone and natriuretic peptides.

Martindale et al. reported in 2016 (Academic Emergency Medicine) high positive likelihood ratio of pulmonary edema observed on lung ultrasound and low negative likelihood ratio of B-line pattern on lung US in affirming the presence of acute heart failure, after a systematic review and analysis of 57 prospective and cross-sectional studies (n = 1,918).

A useful Systematic Review “Emergency department ultrasound for the detection of B-lines in the early diagnosis of acute decompensated heart failure: a systematic review and meta-analysis ” from McGivery et al from SJRHEM (7), was published in 2018.


 

Learning Point

For a patient presenting to the ER with dyspnea, using PoCUS to observe 3 or more B-lines in two bilateral lung zones +/- pleural effusion can rapidly guide an accurate diagnosis of acute congestive heart failure.


 

References

  1. Taylor, T., Meer, J., Beck, S. Emerg Med. (2015) https://www.mdedge.com/emergencymedicine/article/96697/imaging/emergency- ultrasound-lung-assessment Last accessed Feb 29, 2020
  2. Lee, FCY, Jenssen, C., Dietrich, CF Med Ultrason (2018); 20(3): 379-384
  3. Ang SH. & Andrus P Curr Cardiol Rev. 2012 May; 8(2): 123-136https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3406272/
  4. Al. Deeb M., Barbic S., Featherstone R., Dankoff J., Barbic D. Acad Emerg Med 2014 Aug; 21(8): 843-52 https://www.ncbi.nlm.nih.gov/pubmed/25176151
  5. Pivetta E et al. Chest. 2015 Jul; 148(1): 202-210 https://www.ncbi.nlm.nih.gov/m/pubmed/25654562/
  6. Martindale JL, Wakai A, Collins SP, Levy PD, Diercks D, Hiestand BC, Fermann GJ, deSouza I, Sinert R, Acad Emerg Med. 2016 Mar; 23(3): 223-242 https://www.ncbi.nlm.nih.gov/pubmed/26910112
  7. McGivery K, Atkinson P, Lewis D, et al. Emergency department ultrasound for the detection of B-lines in the early diagnosis of acute decompensated heart failure: a systematic review and meta-analysis. CJEM. 2018;20(3):343‐352. doi:10.1017/cem.2018.27

 

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Introduction to Transesophageal Echo – Basic Technique

Thanks to Dr. Jennifer Cloutier, Cardiac Anesthesiologist, for delivering a great session.


This beginner guide is designed for those familiar with transthoracic echo and just starting to use TEE. ED indications and TEE utility in the emergency setting are briefly discussed at the end of this post.


Requirements

  • Sterile transducer – This requires a sterilization facility, protocol and collaboration with other departments
  • Patient preparation – In ED usually intubated, unconscious or sedated.
  • Optional – spray the transducer with topical local anesthetic

Contraindications

  • Suspected esophageal perforation, stricture or trauma
  • Varices

Insertion

  • Hold transducer control module with left hand and support against your abdomen (see pic 1)
  • Extend transducer to full length, holding end with right hand
  • Check the control wheels are functioning correctly before inserting the transducer
  • Ensure transducer head is facing upwards (use anterior length markings to maintain orientation)
  • Insert transducer on left side of tongue
  • Use bite guard – e.g cut corrugated airway tubing
  • Advance to mid esophagus
  • Look for left atrium – this is the first window

 

Orientation

The transducer can be manipulated into several orientations:

  • Rotate control module clockwise to orientate to patient right
  • Rotate control module anticlockwise to orientate to patient left
  • Rotate “Big Wheel” clockwise to antiflex and orientate anteriorly
  • Rotate “Big Wheel” anticlockwise to retroflex and orientate posteriorly
  • Rotate “Small Wheel” clockwise to flex right
  • Rotate “Small Wheel” anticlockwise to flex left
  • Advance transducer deeper into esophagus
  • Withdraw transducer less deeply in esophagus

(a) Advance, withdraw: Pushing or pulling the tip of the TEE probe; (b) turn to right, turn to left (also referred as clockwise and anticlockwise): rotating the anterior aspect of the TEE probe to the right or left of the patient; (c) anteflex, retroflex: anteflex is flexing the tip of the TEE probe anteriorly by turning the large control wheel clockwise. Retroflex is flexing the tip of the TEE probe posteriorly by turning the large wheel anticlockwise; (d) Flex to right, Flex to left: flexing the tip of the TEE probe with the small control wheel to the patient’s right or left. The probe flexion to the right and left may not be necessary and should be avoided to minimize trauma to the esophagus 

 

 

Multiplane Imaging Angle

With all modern TEE transducers the transducer beam can be rotated within the probe to generate different beam angles. This is achieved using 2 buttons on the control module, one button rotates from 0 to 180 degrees, the other button rotates it back from 180 to 0 degrees. Using the buttons in combination any desired angle between 0 and 180 degrees can be achieved.

At 0 degrees the transducer beam is transverse (orientated Left screen – Right patient)

At 90 degrees the transducer beam is longitudinal

At 180 degrees the transducer beam is transverse (orientated Left screen – Left patient)

 

Multiplane Imaging angle is depicted on the monitor using a pictogram dial.

In this example the TEE probe is located in the Mid Esophageal location. View A – the multiplane imaging angle is 10 degrees and a 4 chamber view is generated. View B – the multiplane imaging angle is 90 degrees and a 2 chamber view is generated.

 

 


 

Useful video tutorial explaining orientation

 

 


 

Core Views

For the beginner, standard views can be achieved by using a guide that shows the location of the transducer (e.g Mid Esophageal, Trans-Gastric along with the optimal multiplane angle (see below).

Clearly every patient will have slightly different anatomy and cardiac axis, so these guides are just a starting point. Fine tuning of all the above will be required.

The Consensus Statement of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists provides an excellent outline of the basic perioperative TEE examination. Although this examination is likely to be much more comprehensive than what is needed in the Emergency Department (e.g during a code or peri arrest), it provides a useful guide to practicing all the important views that may be required in most situations.

 


 

This short video tutorial provides a useful outline of core views

 


ME 4 Chamber View


 

Indications

  • Cardiac Arrest – continuous echo evaluation of cardiac contractility, without impacting chest compression
  • Peri Arrest – assists with diagnosis and fluid resuscitation,
  • Undifferentiated Hypotension – assists with diagnosis and fluid resuscitation

US Probe: Transesophageal Echocardiography in Cardiac Arrest

The post above and the article below provide a more detailed discussion on the use of TEE in cardiac arrest.

New Concepts of Ultrasound in the Emergency Department: Focused Cardiac Ultrasound in Cardiac Arrest

 

 


References

Reeves ST, Finley AC, Skubas NJ, et al. Basic perioperative transesophageal echocardiography examination: a consensus statement of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. J Am Soc Echocardiogr. 2013;26(5):443–456. doi:10.1016/j.echo.2013.02.015

Arntfield, Robert et al. Focused Transesophageal Echocardiography by Emergency Physicians is Feasible and Clinically Influential: Observational Results from a Novel Ultrasound Program. Journal of Emergency Medicine, Volume 50, Issue 2, 286 – 294

 


Further Reading and Viewing

 

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PoCUS in Pericardial Effusion

Medical Student Clinical Pearl – October 2019

 

Alex Pupek

Faculty of Medicine
Dalhousie University
CC4
Class of 2020

Reviewed and Edited by Dr. David Lewis

All case histories are illustrative and not based on any individual


Case

A 70F with a history of bladder CA, HTN and 4.9cm AAA presented to the Emergency Department (ED) and was Triaged as Level 3 with a chief complaint of generalized weakness. Initial assessment was significant for hypotension and low-grade fever with dysuria elicited on history; she was started on Ceftriaxone with a working diagnosis of urosepsis. Bloodwork and imaging studies were sent to rule out other potential sources of infection.

She had a mild leukocytosis of 12.4, pH of 7.23 and a lactate of 5.0. Point-of-care urinalysis was unremarkable. The chest x-ray revealed an enlarged cardiothoracic ratio of 0.62 compared to 0.46 ten months previously, concerning for a pericardial effusion.

Upon reassessment, the patient appeared unwell with slight mottling to the skin, cool extremities and tenuous blood pressure; point of care ultrasound revealed a large pericardial effusion.  Interventional cardiology was paged; the patient was moved to the trauma area and an emergent pericardiocentesis was performed: 360cc of bloody fluid was removed. The pericardial drain was left in situ.

Post-procedure bloodwork included a troponin of 216 and CK of 204. The patient was admitted to the Cardiac Care Unit and discharged within a week’s time.

 


Pericardial Effusions and The Role of Point-of-Care Ultrasound (POCUS)

The normal pericardial sac contains up to 50 mL of plasma ultrafiltrate [1]. Any disease affecting the pericardium can contribute to the accumulation of fluid beyond 50mL, termed a pericardial effusion. The most commonly identified causes of pericardial effusions include malignancy and infection (Table 1).

 

Table 1 – UpToDate, 2019 – Diagnosis and Treatment of Pericardial Effusions


 

Evaluation of the pericardium with point-of-care ultrasound includes one of four standard views: parasternal long axis, parasternal short axis, subxiphoid and apical (Figure 1). A pericardial effusion appears as an anechoic stripe or accumulation surrounding the heart. Larger effusions may completely surround the heart while smaller fluid collections form only a thin stripe layering out posteriorly with gravity. Seen most commonly post-cardiac surgery, pericardial effusions may be loculated and compress only a portion of the heart. [1,2] (Table 2)

Figure 1[1]


Table 2 [2]


 

Both the pericardial fat pad and pleural effusions can be mistaken for pericardial effusions. The parasternal long-axis view is most helpful to accurately define the effusion with the descending aorta, posterior to the mitral valve and left atrium, serving as a landmark: the posterior pericardial reflection is located anterior to this structure. Fluid anterior to the posterior pericardial wall is pericardial, whereas a pleural effusion will lie posterior. The pericardial fat pad is an isolated dark area with bright speckles, located anteriorly; unlike fluid, it is not gravity dependent. Rather than competing with the cardiac chambers for space within the pericardial sac, the fat pad moves synchronously with the myocardium throughout the cardiac cycle. [1,2] (Figure 2)

Figure 2[1]


A pericardial effusion discovered on POCUS in the ED may be mistaken for tamponade, leading to inappropriate and invasive management in the form of pericardiocentesis.[2]

Patient tolerance of pericardial effusions depends on the rate by which they accumulate. As little as 150-200 mL of rapidly accumulating effusion can cause tamponade whereas much larger amounts of slowly accumulating fluid can be well tolerated. Pericardial effusions formed gradually are accommodated by adaptations in pericardial compliance. A tamponade physiology is reached once the intrapericardial pressure overcomes the pericardial stretch limit.[2] (Figure 3)

Figure 3[2]


The core echocardiographic findings of pericardial tamponade consist of:

  • a pericardial effusion
  • diastolic right ventricular collapse (high specificity)
  • systolic right atrial collapse (earliest sign)
  • a plethoric inferior vena cava with minimal respiratory variation (high sensitivity)
  • exaggerated respiratory cycle changes in mitral and tricuspid valve in-flow velocities as a surrogate for pulsus paradoxus

In the unstable patient with clinical and echocardiographic findings of tamponade, an emergent pericardiocentesis is indicated.[2]

A retrospective cohort study of non-trauma emergency department patients with large pericardial effusions or tamponade, ultimately undergoing pericardiocentesis, found that effusions identified by POCUS in the ED rather than incidentally or by other means saw a decreased time to drainage procedures, (11.3 vs 70.2 hours, p=0.055).[3]

Point of care ultrasound is a valuable tool during the initial evaluation of the undifferentiated hypotensive emergency department patient but should be interpreted judiciously and within clinical context to avoid unnecessary emergency procedures.


Additional Images

From GrepMed


 

echocardiogram-pericardial-tamponade-alternans-effusion

 


References

  1. Goodman, A., Perera, P., Mailhot, T., & Mandavia, D. (2012). The role of bedside ultrasound in the diagnosis of pericardial effusion and cardiac tamponade. Journal of emergencies, trauma, and shock, 5(1), 72.
  2. Alerhand, S., & Carter, J. M. (2019). What echocardiographic findings suggest a pericardial effusion is causing tamponade?. The American journal of emergency medicine, 37(2), 321-326.
  3. Alpert, E. A., Amit, U., Guranda, L., Mahagna, R., Grossman, S. A., & Bentancur, A. (2017). Emergency department point-of-care ultrasonography improves time to pericardiocentesis for clinically significant effusions. Clinical and experimental emergency medicine, 4(3), 128.

 

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PoCUS assisted lumbar puncture

PoCUS assisted lumbar puncture

Resident Clinical Pearl (RCP) November 2019

Allyson Cornelis – PGY3 FMEM Dalhousie University, Saint John NB

Reviewed by Dr. Kavish Chandra

 

Lumbar punctures (LPs) are an essential emergency physician skill. Indications including assessing for serious causes of headaches such as meningitis and subarachnoid hemorrhage.

Various limitations to successful lumbar puncture include a large body habitus, arthritic spines, and altered spinal anatomy. Furthermore, this leads to increased procedural risks (failed attempts, pain, hematoma formation, infection and traumatic tap leading to difficult CSF interpretation)


Traditional lumbar puncture

The traditional way to perform a LP is using surface landmarks. The superior iliac crests are identified and a line is drawn across the back to connect them. This helps in identifying L3/L4 space. This is deemed a safe place for LP as the spinal cord ends above this.

 

PoCUS guided lumbar puncture

Ultrasound has become a common tool used in the emergency department for assessment of patients and to assist in certain procedures. Lumbar puncture is one procedure where ultrasound has potential to increase success.1,2

 

The evidence

Meta-analysis of PoCUS guided LPs in the ED with adult and pediatric patients showed improved success rates (NNT 11) and fewer traumatic taps (NNT 6), less pain and less time to obtaining a CSF sample.4

Similar studies in neonates and infants showed reduced LP failure and traumatic taps in the PoCUS guided LP group.5

 

The procedure

The goal of the LP is to place a needle into the subarachnoid space where the CSF can be sampled. At the safe level, LP needle moves in-between the caudal equina.

Adapted from Tintinalli’s Emergency Medicine : A Comprehensive Study Guide, 8th ed.

 

Landmark based LP (briefly)

Place the patient in the lateral decubitus or seated position, allowing them to curve their spine and open the space between adjacent spinous processes

Identify the superior iliac spines and connect a line between the two iliac spines across the back (this should intersect the L4 spinous process).

LP can be safely performed in the L3/4 or L4/5 interspaces. During the procedure, the needle is directed towards the patient’s umbilicus.

 

PoCUS guided LP2,3,6

Identify the midline

  • Position patient either sitting with a curved lumbar spine or laying down in a lateral decubitus position with back perfectly perpendicular to the table and not angled at all. Using either a linear or curvilinear probe (curvilinear is recommended for obese patients), in the transverse plane start at the sacrum which will appear as a bright white line.
  • Move the transducer towards the patient’s head while maintaining a transverse orientation. A space will appear followed by a smaller bright curved line with posterior shadowing, this is the L5 spinous process.

  • Center the spinous process in your screen, and mark the location with a surgical marking pen.

  • Continue moving the transverse transducer cephalad, you will see the interspaces (lack of spinous process and the accompanying shadow and possibly evidence of the articular processes which appear as bat ears).
  • Connect each mark identifying the spinous processes—this marks the midline of the spine

 

Identify the interspaces

  • Turn the transducer into the saggital plane with the indicator towards the patient’s feet (to line up the patient’s head with the view on the screen).

  • Place transducer along the spinal line you marked, starting at the top, and identify the spinous processes and the interspaces.
  • Place the interspace in the center of the transducer and mark with a line. Move caudally, identifying the remaining interspaces.

  • Connect these lines to your spinal line. Where they intersect are the ideal locations for needle entry.

 

The bottom line

Ultrasound is a tool being utilized more often in clinical practice, including in the emergency department. Research shows that its use in obtaining lumbar punctures has potential benefits, including more success in obtaining a CSF sample and less traumatic taps, with minimal harms or downsides to use of the ultrasound.

 

Copyedited by Kavish Chandra

 

Resources:

  1. Ladde JG. 2011. Central nervous system procedures and devices. In: Tintinalli JE, Stapczynski JS, Cline DM, Ma OJ, Cydula RK, Meckler GD, editors. Tintinalli’s emergency medicine: Acomprehensive study guide. 7th ed. China: McGraw-Hill Companies, Inc. p 1178-1180.
  2. Millington SJ, Restrepo MS, Koenig S. 2018. Better with ultrasound: Lumbar puncture. Chest 2018. 154(5): 1223-1229.
  3. Ladde JG. 2020. Central nervous system procedures and devices. In: Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH, editors. Tintinalli’s emergency medicine: A comprehensive study guide. 9th ed. New York, NY: McGraw-Hill: http://accessmedicine.mhmedical.com.ezproxy.library.dal.ca/content.aspx?bookid=2353&sectionid=221017819. Accessed November 17,2019.
  4. Gottlieb M, Holladay D, Peksa GD. 2018. Ultrasound-assisted lumbar punctures: A systematic review and meta-analysis. Acad Emerg Med. 2019 Jan. 26(1). 85-96.
  5. Olowoyeye A, Fadahunsi O, Okudo J, Opaneye O, Okwundu C. 2019. Ultrasound imaging versus palpation method for diagnostic lumbar puncture in neonates and infants: A systematic review and meta-analysis. BMJ Pediatrics Open. 2019 Mar. 3(1):e000412.
  6. Jarman B, Hoffman B, Al-Githami M, Hardin J, Skoromovsky E, Durham S, et al. Ultrasound and procedures. In: Atkinson P, Bowra J, Harris T, Jarman B, Lewis D, editors. Point of Care Ultrasound for Emergency Medicine and Resuscitation. 1st ed. United Kingdom: Oxford University press; 2019. p. 198-199.
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Pediatric Hip PoCUS

Pediatric Hip PoCUS

PoCUS Pearl

Dr. Sultan Ali Alrobaian

Dalhousie EM PoCUS Fellowship

Saint John, NB

@AlrobaianSultan

 

Reviewed and Edited by Dr. David Lewis


 

Case:

A 5 year old healthy boy, came to ED with history of limping since waking that morning. He had worsening right hip discomfort. No history of trauma. He had history of cold symptoms for the last 3 days associated with documented low grade fever.

On physical examination, he looked uncomfortable and unwell looking, he had temperature of 38.1 C, HR 130, BP 110/70, RR 20 and O2 saturation of 98% on RA. He was non-weight-bearing with decreased ROM of right hip because of pain.

Pelvis x-ray was unremarkable, he had WBC of 14.4 x 103  and CRP of 40 .

PoCUS of the right hip was performed.


 

Pediatric Hip Ultrasound

Ultrasonography is an excellent modality to evaluate pathologies in both the intra-articular and extra-articular soft tissues including muscles, tendons, and bursae. PoCUS to detect hip effusion can serve as an adjunct to the history and physical examination in case with hip pain.  It is easily accessible, no radiation exposure and low cost.

Technique:

The child should be in supine position. Expose the hip with drapes for patient comfort. If the patient will tolerate it, position the leg in slight abduction and external rotation. A high frequency linear probe is the preferred transducer to scan the relatively superficial pediatric hip, use the curvilinear probe if increased depth is required.

With the patient lying supine, identify the greater trochanter on the symptomatic hip of the patient. Place the linear probe in the sagittal oblique plane parallel to the long axis of the femoral neck (with the indicator toward the patient’s head).

If the femoral neck cannot easily be found, it can be approached using the proximal femur. Place the probe transversely across the upper thigh. Identify the cortex of the proximal femur and then move the probe proximally until the femoral neck appears medially, then slightly rotate the probe and move medially to align in the long axis of the femoral neck.

Assistance is often required from a parent who may be asked to provide reassurance, apply the gel and help with positioning.

Both symptomatic and asymptomatic hips should be examined.

Negative hip ultrasound in a limping child should prompt examination of the knee and ankle joint (for effusion) and the tibia (for toddler’s fracture)

Hip X-ray should be performed to rule out other causes (depending on age – e.g. Perthes, Osteomyelitis, SCFE, Tumour). Limb X-ray should be performed if history of trauma or NAI.

 

Anatomy of the Pediatric Hip:

The ED Physician should readily identify the sonographic landmarks of the pediatric hip. These landmarks include the femoral head, epiphysis and neck, acetabulum, joint capsule and iliopsoas muscle and tendon.

 

A normal joint may have a small anechoic stripe (normal hypoechoic joint cartilage) between cortex and capsule. This will measure less than 2mm and be symmetrical between hips.

 

Ultrasound Findings:

Measure the maximal distance between the anterior surface of the femoral neck and the posterior surface of the iliopsoas muscle. An effusion will result in a larger anechoic stripe (>2mm) that takes on a lenticular shape as the capsule distends. Asymmetry between hips is confirmatory. Synovial thickening may also be visualized.

FH- Femoral Head, S- Synovium, E – Effusion, FN – Femoral Neck

Criteria for a pediatric hip effusion is:

  • A capsular-synovial thickness of 5 mm measured at the concavity of the femoral neck, from the anterior surface of the femoral neck to the posterior surface of the iliopsoas muscle
  • OR a 2-mm difference compared to the asymptomatic contralateral hip

Right hip effusion, normal left hip, arrow heads – joint capsule, IP – iliopsoas


Interpretation

PoCUS has high sensitivity and specificity for pediatric hip effusion.

  • —
  • Sensitivity of 90%
  • Specificity of 100%
  • Positive predictive value of 100%
  • Negative predictive value of 92%

 

PoCUS cannot determine the cause of an effusion. It cannot differentiate between transient synovitis and septic arthritis. Diagnosis will be determined by combining history, pre-test probability, examination, inflammatory markers and PoCUS findings. If in doubt, septic arthritis is the primary differential diagnosis until proven otherwise.

Several clinical prediction algorithms have been proposed. This post from pedemmorsels.com outlines these nicely:

 

Septic Arthritis

 

 


 

Back to our case:

Ultrasonography cannot definitively distinguish between septic arthritis and transient synovitis, the ED physician’s concern for septic arthritis should be based on history, clinical suspicion and available laboratory findings.

The patient was diagnosed as case of septic arthritis. The patient received intravenous antibiotics empirically. Pediatric orthopedic consultation was obtained, and ED arthrocentesis was deferred as the patient was immediately taken to the operating room for hip joint aspiration and irrigation, confirming the diagnosis.


 

References

 

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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
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Shining a light on acute vision loss: PoCUS for the retina

Shining a light on acute vision loss: PoCUS for retinal pathology

Resident Clinical Pearl (RCP) August 2019

Dr. Devon Webster – PGY2 FMEM Dalhousie University, Saint John NB

Reviewed by Dr. Kavish Chandra

 

It’s a quiet night in RAZ and you pick up your next chart- a 68 year old Ms. Iris Snellen has come in with new onset, painless, monocular vision loss. You pick up the ophthalmoscope to perform fundoscopy, and despite your best attempts, like many ED physicians before you, you see nothing helpful. So instead you pick up your investigative tool of choice, the ultrasound probe, and begin your ocular POCUS exam…


Anatomy and pathophysiology

The retina is composed of multiple layers of neurons that allow for the human eye to convert light energy (photons) into images within the occipital brain. The retina sits on top of the vascular choroid which provides blood flow.

Fundoscopy allows for visualization of the following structures:

  • Optic disc
  • The macula (central, high-resolution, color vision)
  • The fovea (sits centrally in the macula and provides sharp, central vision)
  • The retinal artery and vein

https://stanfordmedicine25.stanford.edu/the25/fundoscopic.html

 

PoCUS is adjunctive test to assess for vision-threatening and common conditions impacting the eye such as retinal detachment (RD), posterior vitreous detachment (VD) and vitreous hemorrhage (VH).

A normal eye should allow you to visualize the following structures:

https://www.nuemblog.com/ocular

In retinal detachment, the retina is separated from the choroid either through formation of a hole in the retina, peeling away from the choroid if attached to the vitreous humour or through edematous infiltration between the two layers. Separation results in rapid ischemia and death of photoreceptors with subsequent vision-loss.

Posterior vitreous detachment is common and occurs secondary liquification of the gel-like vitreous body.

Vitreous hemorrhage can occur secondary trauma, spontaneous retinal tears or vitreous detachment or any cause of retinal neovasculiarzation such as in diabetes.

 


Retinal detachment and the DDx

When assessing your pt, a retinal detachment should be at the top of your list of diagnoses to rule out given that prompt recognition and referral to ophthalmology may be a vision-saving intervention.

On history she may describe the following features of RD:

  • Floaters: may appear as spiderwebs, a large spot that comes and goes that may ‘look like a big fly’ or a showering of many small black dots.
  • Painless monocular vision loss: may present as a ‘curtain descending’ across her vision and/or visual field loss.
  • Flashes: may be easier to see at night or in a dark room (consider turning off the lights in the exam room)

Assess for risk factors for retinal detachment:

  • Myopia (near-sightedness): Major risk factor!
  • Cataract surgery
  • Family history of retinal detachment
  • Diabetes
  • Glaucoma
  • Old age
  • History of posterior vitreous detachment

Physical exam:

  • Assess for changes in visual acuity
  • Assess for loss of visual fields
  • Fundoscopy may reveal advanced detachments however, early detachments are often not visible with direct fundoscopy. Advanced detachments may reveal absence of a red reflex and a billowing retinal flap.
  • Ultrasound!

Your DDx may include:

  • Posterior vitreous detachment
  • Vitreous hemorrhage
  • Ocular migraine
  • CRAO/CRVO
  • Amaurosis fugax

(see below for distinguishing features of the DDx)

 


The PoCUS assessment

Most ED physicians feel more comfortable with their ultrasonography skills over their fundoscopy skills. PoCUS is a fast, portable and radiation-free approach to assessing patients for potential vision-threatening pathology such as retinal detachment. While ultrasonography should not replace ophthalmologic assessment and fundoscopy, it can be used as an additional tool to support your primary diagnosis.

Most recently, Lanham, et al., published a prospective diagnostic study involving 225 patients and 75 ED providers that found POCUS was 96.9% sensitive and 88.1% specific for the diagnosis of retinal detachment1. While studies have varied in whether sensitivity was better than specificity or vice versa, ultimately each study has shown that when trained, emergency providers are quite good at identifying RD by US2,3. In addition to RD, Lanham, et al further found ED providers did well at identifying vitreous hemorrhage (sens 81.9%, sp 82.3%) and vitreous detachment (sens 42.5%, sp 96%).

Get the PoCUS Scan:

  • Place a tegaderm over the eye to protect it from US gel which may be painful. You may consider using topical freezing drops to limit irritation.
  • Use the linear probe and scan through the eye until you are able to visualize the optic nerve, the hypoechoic structure at the back of the eye
  • Have the patient look side to side/up and down as this will accentuate movement of retinal or vitreous pathology.
    1. Retinal detachment: Bright echogenic line that appears to have separated from the posterior eye/choroid and remains tethered to the optic nerve.
    2. Posterior vitreous detachment: Bright echogenic line separated from posterior eye/choroid that is detached from the optic nerve.
    3. Posterior vitreous hemorrhage: Vitreous shows fluid collection with variable echogenicity and ‘washing machine’ appearance.

Jacobsen et al. (2016). WestJEM. 17(2)

 

Differential of painless visual loss

 

Resources:

  1. Lahham S, et al. Point-of-Care Ultrasonography in the Diagnosis of Retinal Detachment, Vitreous Hemorrhage, and Vitreous Detachment in the Emergency Department. JAMA Netw Open. Published online April 12, 20192(4):e192162. doi:10.1001/jamanetworkopen.2019.2162
  2. Kim, D., et al. Test Characteristics of Point-of-care Ultrasound for the Diagnosis of Retinal Detachment in the Emergency Department. Academic Emergency Medicine. 2019;26[1]:16; http://bit.ly/2TEFutH
  3. Vrablik ME, et al. The diagnostic accuracy of bedside ocular ultrasonography for the diagnosis of retinal detachment: a systematic review and meta‐analysis. Ann Emerg Med 2015; 65( 199–203): e1.
  4. Mason, J. (Host). (2019 Jan). C3-Vision Loss-Retinal Detachment [Audio podast]. Retrieved from EMRAP: https://www.emrap.org/episode/c3visionloss/c3visionloss1 .
  5. Arroyo, J. (Jan 2018). Retinal Detachment. Retrieved from Uptodate: https://www.uptodate.com/contents/retinal-detachment
  6. Givre, S., et al. (Feb 2019). Amaurosis fugax (transient monocular or binocular visual loss). Retrieved from Uptodate: https://www.uptodate.com/contents/amaurosis-fugax-transient-monocular-or-binocular-visual-loss?search=painless%20monocular%20vision%20loss&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
  7. Porfiris, G. (2015). ABCs of Emergency Medicine, 14th Edition, Chapter 23: Eye Emergencies.

 

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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.
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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

 

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