Category Archives: Ultrasound

Managing alcohol withdrawal

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EM Reflections Sept 2021 – Managing alcohol withdrawal

Authored and Copyedited by Dr. Mandy Peach

Big thanks to Dr. Paul Page for leading this month’s discussions.

All cases are imaginary but highlight important learning points.

 

Case

A 72 yo male presents to the emergency department with left sided CP after sustaining a fall 3 days ago. He states he hasn’t slept and is having a hard time breathing due to the pain – “ I think I cracked a rib”. On further history surrounding the fall he divulges that he was quite intoxicated at the time of injury and that he does fall quite often when drinking. He drinks 8-10 beers per day, sometimes more, and has done so for many years. He denies any complications of his drinking other than frequent injuries and has never been admitted or attended a rehabilitation facility.

Financially there have been increasing constraints and currently he is unable to obtain alcohol. His last drink was 2 days ago. He states he feels uneasy and slightly nauseous with a mild headache, but he feels it is related to the chest pain.

His PMH is non-contributory – he has no family doctor and has no regular care. He has smoked 1-2ppd for “as long as I can remember”.

His vital signs: 142/76, HR 112, RR 20, O2 93% on RA, T 36.7. He appears diaphoretic, mildly uncomfortable and taking shallow breaths.

Physical exam for signs of trauma reveals no significant injury except for a small area of bruising and tenderness at the L 10th rib with air entry heard bilaterally. As the trauma was 2 days ago, and he is satting 93% on RA on a background of suspected COPD, you feel it is unlikely he has any complication of his fall. Imaging is unlikely to change your management – he needs analgesia.

You instead focus on his alcohol use as you suspect that is what is contributing most to his symptoms.

What are symptoms/signs of alcohol withdrawal? How soon do you anticipate symptoms?1,2

A spectrum – early withdrawal -> seizures -> alcoholic hallucinosis -> delirium tremens (DT).

Symptoms Signs
Abdominal pain Tachycardia
Nausea/vomiting Elevated BP
Headache Tremor – The tremor is key to diagnosis. It is an intention tremor – when resting it is not visible. Ask the patient to extend their arms/hands and it becomes apparent. This is a persistent tremor and it does not fatigue
Anxiety Tongue Tremor – more sensitive finding. See video
Hallucinations – clear cognition with hallucinations *High risk deterioration to DT Seizures – occur at 12-48 hours and are typically preceded by tremor

 

 

Tongue tremor1

Symptoms from alcohol withdrawal can start as early as 6-8 hours after the last drink, as the alcohol levels decline.

Symptoms typically peak at 72 hours and are gone by day 5-7.

Delirium Tremens can be anytime from day 3-12 after abstinence.

You examine your patient for signs of withdrawal. From the vitals he is tachycardiac. On exam he appears diaphoretic and he complains of a few symptoms. You ask him to extend his arms and he does have an intention tremor that doesn’t fatigue.

You confirm he is in alcohol withdrawal – this is a clinical diagnosis.

Are there any investigations that should be done for acute alcoholic withdrawal?

It depends on the patient presentation and the level of severity.

Mild cases – lab work/imaging rarely contributory. But there are situations where it is warranted.

  • Severe symptoms with potential DTs – really this could be a patient with acute delirium of any etiology. So screen for :
    • electrolyte abnormalities
    • alcoholic ketoacidosis
    • infection
    • toxidromes
    • thyrotoxicosis
    • neuroleptic malignant syndrome
    • serotonin syndrome
    • hypertensive crisis
    • acute pain
    • ECG – chronic alcohol use leads to hypomagnesemia and electrolyte abnormalities, increasing risk of long QT.
    • CT head – These patients are high risk for falls during both intoxication and withdrawal. Combine this with fragile intracranial bridging veins and potential coagulopathy if underlying liver disease and their risk of ICH goes up substantially.

 

  • Unclear history? Maybe the patient is not in DTs but actually is acutely intoxicated. An alcohol level can be ordered, but keep in mind that patients experiencing withdrawal will have symptoms at varying levels. Chronic users may have withdrawal symptoms at a level that is intoxicating to someone who rarely drinks. Add a urine tox screen if concern for co-ingestants as above.

 

So, if alcohol levels aren’t helpful how do I differentiate between an acute alcoholic intoxication vs severe withdrawal with DTs?1

Giving benzodiazepines to a patient who is acutely intoxicated can lead to decreased LOC.

Before considering treatment look for the withdrawal tremor – if it isn’t present they are likely intoxicated.

 

The CIWA-Ar protocol is one method to monitor withdrawal symptoms and quantify the severity to ensure the patient receives appropriate treatment.

https://insight.qld.edu.au/shop/clinical-institute-withdrawal-assessment-of-alcohol-scale-revised-ciwa-ar-insight-2019

This is a 10 item scale and is done hourly. If a patient scores > 10 they are treated, if  back to back scores are < 10 they can be discharged.

Is there a faster tool that can be used in the ED to quantify alcohol withdrawal?1

SHOT protocol is a 4-item scale. It is done every 1-2 hours. It is not validated, but has been shown to correlate well with CIWA score. It is shorter and easier to administer. Patient can be discharged if back to back scores are 0-1.

You decide to calculate your patient’s SHOT score3.

You calculate the patient’s SHOT score to be 6

  • Sweating: He has beads of sweat on his forehead (2)
  • Hallucinations: He has no hallucinations (0)
  • Orientation: He knows where he is, but gets the month wrong (1)
  • Tremor: he has a moderate intention tremor (3)

Any score over 2 requires medical intervention

Your patient requires intervention.

What medication do you choose to treat alcohol withdrawal?

Longer acting benzodiazepines are preferred as they have a more predictable course and are less likely to result in withdrawal or seizures 1,2,4.

Lorazepam Diazepam
Onset of action Slower Faster
Half-life 8-12 hours 100 hours
Duration of action 12 hours 5 days
Risk withdrawal Higher Lower
Sedation risk Less risk of oversedation

Use if liver dysfunction as less systemic accumulation

 Oversedation risk if liver dysfunction, elderly, low albumin, methadone or high dose opiods

Use oral doses if mild withdrawal and the patient can tolerate.

You order oral diazepam for the patient when a trauma team activation is heard overhead – it is a multiple vehicle MVC. Currently the department is critically understaffed, and all available staff are sent to trauma while one nurse manages the acute patients.

A couple of hours have passed and you finally get back to reassess your withdrawal patient. He has since had a CT head that showed the expected atrophy but no hemorrhage. You review his lab values and other than some mild electrolyte abnormalities there are no glaring values or signs of co-ingestants. You hear raised voices in the department and go to assess. Your patient now appears to the hallucinating and is severely agitated. He is not responding to verbal de escalation. A code white is called. The patient is restrained and a glucose is immediately checked to r/o hypoglycemia – it is 5.8. IV access is still intact.

Your patient is likely experiencing DTs and is in severe withdrawal.

What medication do you want to avoid in this agitated patient withdrawing from alcohol1?

Haldol – antipsychotics can prolong QT interval in patients already at risk of long QT. It can also lower seizure threshold.

How do you manage severe alcohol withdrawal 5?

Lots of benzos via IV with the goal of having a calm, cooperative patient.

Start with diazepam 10 mg IV and reassess in 5 minutes, if not suffice then re-dose another 10mg. If still no success than increase the dose increase by 10mg and repeat that pattern, reassessing every 5 mins.

What if the patient doesn’t respond to these treatments?

Once approaching 200mg total – these patients are benzo resistant and will likely require intubation (*keeping in mind you’ve considered other etiologies)5.The same is true for refractory seizures that have not responded to escalating benzodiazepine doses.

Before proceeding to intubation you can consider phenobarbital as adjunct, but there is no evidence that phenobarbital alone is superior to benzos in treating withdrawal. The side effect profile is also higher if using an anticonvulsant instead of a benzodiazepine 2.

If you intubate the patient, consider the following adjuncts6:

Of these – phenobarbital, propofol and dexmedetomidine have been shown to decrease benzodiazepine requirements in severe withdrawal, but none are proven to shorten duration of illness of length of stay in ICU.

If using demedetomidine you must have another adjunct as it does not protect against withdrawal seizures.

The following is a summary1

 

You administer escalating benzodiazepine doses to your patient and eventually he settles. You are charting and preparing to admit the patient when the nurse lets you know the patient is now on 2L of oxygen despite having a normal respiratory rate and end tidal. His GCS is 13 – he opens his eyes to speech, is responding to questions but seems confused still and is moving spontaneously to command.

You go to reassess. You confirm the GCS and don’t feel that it is contributing. You remember the low oxygen saturation on initial vitals you thought was secondary to underlying COPD. You auscultate the lungs and now notice decreased air entry to the L side. In the setting of recent trauma you are concerned your patient had a pneumothorax that worsened.

Would PoCUS have been of benefit in initial assessment of the patient?

It depends on the thoroughness of the scan.

There is evidence that a single view of the anterior chest in the midclavicular line, 3rd intercostal space, is comparable to a 4-zone lung scan for finding a clinically significant pneumothorax in the setting of blunt trauma. In this study clinically significant means those pneumothoraces that required thoracostomy7.

So, using this single view approach smaller pneumothoraces can be missed. But they are less likely to require a chest tube up front.

Could this patient have had a small traumatic pneumothorax that worsened in the setting of his agitation? Could he have had a secondary spontaneous pneumothorax in the setting of COPD?

Without imaging of some sort before hand it is difficult to know with certainty. Keep in mind that CXR has a sensitivity of 20-48% for pneumothorax 6. A thorough PoCUS exam has a higher sensitivity and equivocal specificity for pneumothorax in the setting of blunt trauma6. Gold standard? CT of course.

Regardless, have a low threshold to image elderly people in the setting of trauma.

You place a probe in the 3rd IC space anteriorly and see the following

There is lack of lung slide or comet tails/B lines suspicious for pneumothorax.

What can complicate interpretation of a lung scan for pneumothorax? What is the most specific sign of pneumothorax?

In certain patient populations (ie. critically ill ICU patients, ARDS, pneumonia, fibrosis, pleurodesis, cardiopulmonary arrest) the typical findings of lack of lung sliding and B lines are not reliable.

Absence of lung sliding does not diagnosis pneumothorax (spec 78-91%) in these patients.

Definite sign? Lung point, or the area where the visceral pleural begins to separate from the parietal pleural – it is 100% specific.

You confirm a pneumothorax and place a chest tube without complication. You now CT the patient looking for further injury. The CT confirms multiple L sided rib fractures with a small hemothorax and reinflation of the pneumothorax. There is also stable, but acute, thoracic spine fractures.

The patient is admitted to the ICU for severe alcohol withdrawal in the setting of trauma.

What extra treatments do you consider before handing over to the ICU staff1,2?

Fluids – often these patients are hypovolemic and hypoglycemic. Consider glucose containing fluids.

High dose Thiamine – thiamine deficit patients can develop Wernicke’s encephalopathy. Glucose and thiamine compete for the same co-factor so theoretically giving glucose in a thiamine deficient patient could precipitate Wernicke’s. However, there is no evidence that a single glucose dose will cause this. So, give glucose at the same time or after thiamine, but if critically low glucose don’t wait to administer.

Magnesium – required for thiamine related kinetics and is often low in this population. Check and replace when giving thiamine2.

 

The patient did well and upon discharge he was provided resources and support for seeking treatment. He completed the detox while admitted.

What about patients being discharged from the emergency department with mild alcohol withdrawal? How are they managed 1?

Key is avoiding prescription for benzodiazepine as an outpatient. This has a risk of oversedation, dependence and drug seeking behaviour. Giving diazepam in the ED can prevent seizures due to it’s long half life.

Take home points:

  1. Alcohol withdrawal is a clinical diagnosis – recognize the symptoms and signs.
  2. Persistent intention tremor is a sensitive sign of withdrawal.
  3. Consider other causes in the acutely delirious patient.
  4. These patients are high risk for injury – have a low threshold to image if suspicion of trauma
  5. Quantify the severity for treatment – consider using the SHOT protocol. Diazepam > Lorazepam in the patient with no underlying liver dysfunction.
  6. High, escalating IV benzos for refractory agitation/seizure
  7. Avoid benzodiazepine prescriptions as an outpatient.

 

References and further reading

  1. Helman, A, Borgundvaag, B, Gray, S. Alcohol Withdrawal and Delirium Tremens: Diagnosis and Management.Emergency Medicine Cases. October, 2016. https://emergencymedicinecases.com/alcohol-withdrawal-delirium-tremens/. Accessed [Oct 31, 2021].
  2. Fabian, C. Alcohol: Beyond the “Breakfast Plan”. EM Ottawa. December 2015. https://emottawablog.com/2015/12/alcohol-beyond-the-breakfast-plan/. Accessed [Oct 31, 2021].
  3. Gray S, Borgundvaag B, Sirvastava A, Randall I, Kahan M. Feasibility and reliability of the SHOT: A short scale for measuring pretreatment severity of alcohol withdrawal in the emergency department. Acad Emerg Med. 2010;17(10):1048-54
  4. Hoffman R, Weinhouse G. Management of moderate and severe alcohol withdrawal syndromes. UpToDate. September 2021. https://www.uptodate.com/contents/management-of-moderate-and-severe-alcohol-withdrawalsyndromes?search=alcohol%20withdrawal&sectionRank=1&usage_type=default&anchor=H17&source=machineLearning&selectedTitle=1~150&display_rank=1#H17. Accessed [Oct 31, 2021]
  5. Justin Morgenstern. Management of Delirium Tremens, First10EM, 2016. Available at:

https://doi.org/10.51684/FIRS.1898

  1. Darrel Hughes, “Benzodiazepine-Refractory Alcohol Withdrawal”, REBEL EM blog, April 28, 2016. Available at: https://rebelem.com/benzodiazepine-refractory-alcohol-withdrawal/.
  2. Michael Prats, MD. Comparison of Four Views Versus Single View for Pneumothorax. Ultrasound G.E.L. Podcast Blog. Published on November 7, 2016. Accessed on November 1, 2021. Available at https://www.ultrasoundgel.org/6.
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Alternative Rib Fracture Management in the ED

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Alternative Rib Fracture Management in the ED – A Medical Student Clinical Pearl

Victoria Mercer, Clinical Clerk 3, DMNB

Reviewed and Copyedited by Dr. Mandy Peach

Rib fractures are a frequent presentation in the ED, occuring in approximately 10% of all injured patients with the primary causes being blunt chest trauma and MVAs(1,2).  The mainstay of treatment for rib fractures is analgesic control(1). When pain cannot be adequately managed, the patient is at a heightened risk of hypoventilation due to decreased thoracic mobility and secretion clearance, predisposing the patient to significant atelectasis(1,2).

Historically the pain from rib fractures has been managed with acetaminophen or NSAIDS and if these do not sufficiently alleviate the pain, opioids are used(1,3). Unfortunately, these methods often do not provide adequate pain control or in the case of opioids, come with a myriad of side effects such as nausea, vomiting, constipation, respiratory depression and the potential for dependency and abuse (1,4).

An alternative to traditional methods include regional techniques such as paravertebral or epidural nerve blocks. These interventions have been shown to effectively control pain in rib fractures(3,4). The downside to these interventions include being technically challenging and time consuming with significant complication risks and contraindications such as coagulation disorders (1,3).

The solution? A serratus anterior block 

An ultrasound guided blockade of the lateral cutaneous branches of the thoracic intercostal nerves was first described by Blanco et al. in 2013 for patients following breast surgery to manage their postoperative pain(5). This procedure has been adopted by many emergency departments for its convenience and practicality compared to epidural or paravertebral nerve blocks(3).

Serratus anterior blocks are less invasive and considerably more practical in the ED setting, providing paresthesia to the ipsilateral hemithorax for 12-36 hours (6).

The only absolute contraindications are patient refusal, allergy to local anesthetic and local infection(1).

Complications of a serratus anterior block include pneumothorax, vascular puncture, nerve damage, failure/inadequate block, local anesthetic toxicity and infection(1).

Serratus anterior blocks are only effective for the anterior two-thirds of the chest wall (3).

 

Figure 1. Ultrasound image of serratus anterior muscle and surrounding tissues with superficial or deep needle guides. Image from Thiruvenkatarajan V, Cruz Eng H, Adhikary SD. An update on regional analgesia for rib fractures. Current Opinion in Anaesthesiology. 2018;31(5):601–607.

How do you do it?

The procedure is usually performed with the patient laying supine however the patient could also lay in a lateral decubitus position (1,3). Using a high frequency linear ultrasound probe (6-13MHz), identify the serratus anterior and latissimus dorsi muscles over the fifth rib in the mid-axillary line(1,3). Using an in-plane approach, insert the needle either superficial or deep to the serratus anterior and confirm correct needle placement by visualizing anaesthetic spread via ultrasound(1,3). According to May et al., superficial spreading tends to have a longer lasting analgesic effect(1). Place and secure a catheter to infuse the remainder of the bolus(1,3). Thiruvenkatarajan et al. recommend a bolus of 40ml of 0.25% levobupivacaine and a 50mm 18G Tuohy catheter needle(3).

See this excellent review by Dr. David Lewis on identifying rib fractures and their complications using ultrasound (start 3:08) as well as a review of the block and procedure (start 8:00)

Rib Fractures and Serratus Anterior Plane Block

References

  1.         May L, Hillermann C, Patil S. Rib fracture management. BJA Education. 2016 Jan 1;16(1):26–32.
  2.         Malekpour M, Hashmi A, Dove J, Torres D, Wild J. Analgesic choice in management of rib fractures: Paravertebral block or epidural analgesia? Anesthesia and Analgesia. 2017 Jun 1;124(6):1906–11.
  3.         Thiruvenkatarajan V, Cruz Eng H, Adhikary S das. An update on regional analgesia for rib fractures. Vol. 31, Current opinion in anaesthesiology. 2018. p. 601–7.
  4.         Tekşen Ş, Öksüz G, Öksüz H, Sayan M, Arslan M, Urfalıoğlu A, et al. Analgesic efficacy of the serratus anterior plane block in rib fractures pain: A randomized controlled trial. American Journal of Emergency Medicine. 2021 Mar 1;41:16–20.
  5.         Blanco R, Parras T, McDonnell JG, Prats-Galino A. Serratus plane block: A novel ultrasound-guided thoracic wall nerve block. Anaesthesia. 2013 Nov;68(11):1107–13.
  6.         Mayes J, Davison E, Panahi P, Patten D, Eljelani F, Womack J, et al. An anatomical evaluation of the serratus anterior plane block. Anaesthesia [Internet]. 2016 Sep 1 [cited 2021 Apr 18];71(9):1064–9. Available from: http://doi.wiley.com/10.1111/anae.13549

 

 

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Rib Fractures and Serratus Anterior Plane Block

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Saint John EM Rounds – March 2021

Dr. David Lewis

@e_med_doc

 

View PDF here

Further Reading and Links

 

 

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Lisfranc Injury – We have PoCUS but do we still need the cavalry?

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PoCUS Fellow Pearl

Dr. Melanie Leclerc, CCFP-EM

MSK PoCUS Fellow

Dalhousie University Department of Emergency Medicine

 

Reviewed & Edited by Dr David Lewis (@e_med_doc)

All case histories are illustrative and not based on any individual

 

Case Report

A 32 year old male presents to a rural Emergency Department with a complaint of traumatic left foot pain. He was playing recreational football this evening. While crouching, the patient was tackled by another player who landed on his hyper-plantar flexed left foot from behind. The patient had immediate onset of pain in the middle of his foot and was unable to weight-bear. 

On physical examination, you notice significant bruising and swelling of the mid-foot. There is tenderness to the medial mid-foot specifically at the 1st-2nd tarsal-metatarsal articulations. X-rays of the foot appear normal. You are concerned about the possibility of a ligamentous Lisfranc injury.

https://www.footandanklesurgery.com.au/lisfranc-injuries

 

 

Lisfranc injuries

Lisfranc injuries are those that involve the tarsal-metatarsal joints. A spectrum of injury exists from ligamentous to fracture-dislocation. Up to 20% – 40% of injuries to the Lisfranc complex are missed in the Emergency Department. Unrecognized and untreated injuries can lead to long-term instability through the midfoot. As this region of the foot is responsible for a significant load during weight bearing, instability can accelerate degenerative changes in the foot resulting in chronic pain and disability

The injury is named after Jacques Lisfranc de St. Martin, a French surgeon and gynecologist performed forefoot amputations at the tarsometatarsal joint on cavalrymen, during the 1815 Napoleonic wars. Although he didn’t specifically describe the injury, it has since been recognised in equestrians and occurring as a result of a trapped plantar flexed foot in the stirrup during a fall.

 

Other mechanisms have been described including high velocity injuries (sports injuries, foot on brake pedal MVA) and low velocity injuries (Stepping off a curb awkwardly). Low velocity injuries are more likely to be missed than high velocity injuries.

Further Reading – OrthoBullets

 

Anatomy

The Lisfranc ligament complex is comprised of 3 ligaments. The dorsal (red), interosseous (blue) and the plantar (green) Lisfranc ligaments. The  Interosseous ligament is the largest and the dorsal ligament is the smallest.

The first and second rays have unique ligamentous anatomy wherein no intermetatarsal ligaments exist, but extreme strength is imparted by dorsal, interosseous, and plantar bundles of ligament binding the lateral aspect of the medial cuneiform bone with the medial head of the second metatarsal bone—the Lisfranc ligamentous complex. Only the dorsal and plantar Lisfranc ligaments are accessible to ultrasound.

 

 

 

PoCUS of the Lisfranc joint and dorsal lisfranc ligament (DLL)

Lisfranc injuries are one of the most commonly missed orthopaedic injuries in the Emergency Department. Normal X-rays are often falsely reassuring to providers and patients are discharged with a diagnosis of “soft-tissue injury”. These injuries result in midfoot instability and often require definitive surgical management.

PoCUS has been studied as a method of early detection of these injuries. Specifically, assessment of the dorsal lisfranc ligament (DLL) between the second metatarsal (M2) and the medial cuneiform(C1). PoCUS also has the advantages of being significantly cheaper and more accessible than CT and MRI. Further investigation is needed to validate this method of diagnosis, however ultrasound findings of a disrupted DLL and a widened C1-M2 interval compared to the contralateral side may increase your suspicion when pre-test probability is high.

 

Technique

  1. Linear probe-MSK setting starting at a depth of 2cm
  2. Place probe in transverse orientation over the proximal aspect of the 1st-2nd metatarsals with the probe indicator to the patient’s right
  3. Slide the transducer proximally until you locate the medial cuneiform and identify the junction between the medial cuneiform (C1) and the 2nd metatarsal (M2)
  4. The medial cuneiform will have an angulated contour appearance in contrast to the round appearance of the metatarsals
  5. Sweep to identify the dorsal lisfranc ligament (DLL)
  6. Assess the DLL for a fibrillar pattern, normal echogenicity and contour
  7. Measure the DLL width and the C1-M2 distance compare to the contralateral side
  8. Measure the C1-M2 distance with weightbearing (if patient tolerates) to compare
  9. Apply colour doppler to assess for hyperemia

 

PoCUS Findings

Medial Cuneiform (C1), 2nd Metatarsal (M2)

Note the angulated contour of C1 and the smooth contour of M2 – this sectional plane is important when locating the dorsal Lisfranc ligament. The ligament appears hypoechoic with a fibrillar pattern, typical for other ligaments more commonly visualized with PoCUS e.g MCL, ATFL.

1. Normal image – Arrows = dorsal Lisfranc ligament

2. Normal Clip and annotated image. Note how the dorsalis pedis a. frequently overlies the dorsal Lisfranc ligament (yellow lines)

3. Normal clip. Note how there is no separation of C1/M2 while counterstressing the 1st and 2nd rays

 

4. Thickened, convex contour

5. DLL disrupted, wide joint space

6. Widening C1-M2 with weightbearing

Video Case

 

Limitations

  1. Anisotropy – Irregular dorsal contour of foot can result in difficult perpendicular imaging of doral Lisfranc ligament. Stand-off gel pad may help.
  2. History of prior trauma – chronic Lisfranc injury may result in joint widening
  3. Bilateral injuries – inability to compare sides to judge joint space widening

Application

Standard foot radiographs should be performed in all cases of suspicion for Lisfranc Injury. Weight bearing radiographs should also be performed if tolerated (the ability to fully weight bear is often limited in the acute setting)

HIgh velocity injuries result in significant soft tissue swelling, and although non-weight bearing radiographs may not be diagnostic, the index of suspicion for Lisfranc injury will be high. Immobilization +/- early CT and follow up with foot and ankle specialist is recommended. For these, high pretest probability injuries, PoCUS findings are unlikely to change management significantly. A clear Lisfranc ligament rupture on PoCUS may trigger a request for CT/MRI earlier than otherwise considered. In most cases advanced imaging and a clear diagnosis is not usually possible until the swelling has subsided.

In low velocity injuries, soft tissue swelling is less pronounced. in the acute presentation the ability to perform weight bearing radiographs is limited by pain. Index of suspicion for Lisfranc injury may be low-moderate and the decision to immobilize and refer for specialist follow up can be difficult. While there is limited published evidence for PoCUS test characteristics in Lisfranc injury, a positive scan (injury + disrupted ligament / widening of C1/M2) is likely to be highly specific. Patients with positive PoCUS findings should therefore be immobilized and referred for specialist follow up. In those with negative or inconclusive findings, management and disposition will depend on degree of clinical suspicion and correlated with radiographic findings.

In summary, PoCUS provides a useful additional piece of information that can be plugged into a bayesian diagnostic pathway. What is the pretest probability of a particular diagnosis? After reviewing radiographs and performing PoCUS is the diagnosis more or less likely?

More evidence is required to fully understand the test characteristics of PoCUS for Lisfranc injury. Would the addition of plantar views improve sensitivity?

Although the performing the scan takes only a few minutes, it is quite technically challenging for the novice. As with all MSK PoCUS, repeated practice in numerous patient presentations will increase operator speed and accuracy.

 

Finally, although we still need the cavalry, PoCUS can help us decide which regiment and how quickly we need them!

 

References

  1. Mayich DJ, Mayich MS, Daniels TR. Effective detection and management of low-velocity Lisfranc injuries in the emergency setting: principles for a subtle and commonly missed entity. Can Fam Physician. 2012;58(11):1199-e625. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498011
  2. Woodward, S., Jacobson, J.A., Femino, J.E., Morag, Y., Fessell, D.P. and Dong, Q. (2009), Sonographic Evaluation of Lisfranc Ligament Injuries. Journal of Ultrasound in Medicine, 28: 351-357.
  3. Döring, S., Provyn, S., Marcelis, S., Shahabpour, M., Boulet, C., de Mey, J., De Smet, A., De Maeseneer, M. (2018). Ankle and midfoot ligaments: Ultrasound with anatomical correlation: A review. Eur J Radiol.107:216-226.
  4. Kaicker, J., Zajac, M., Shergill, R., & Choudur, H. N. (2016). Ultrasound appearance of the normal Lisfranc ligament. Emergency Radiology, 23(6), 609-614.
  5. DeLuca, M.K., Walrod, B. and Boucher, L.C. (2020). Ultrasound as a Diagnostic Tool in the Assessment of Lisfranc Joint Injuries. J Ultrasound Med, 39: 579-587.
  6. Marshall, J., Graves, N.C., Rettedal, D.D., Frush, K., Vardaxis. V. (2013). Ultrasound Assessment of Bilateral Symmetry in Dorsal Lisfranc Ligament. The Journal of Foot and Ankle Surgery, 52(3): 319-323.
  7. Rettedal, D.D., Graves, N.C., Marshall, J.J. et al. Reliability of ultrasound imaging in the assessment of the dorsal Lisfranc ligament. J Foot Ankle Res 6, 7 (2013).
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Small Bowel Obstruction & PoCUS

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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

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

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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.9 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. https://sjrhem.ca/pocus-measurements-quick-reference/

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

 

 

 

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Spontaneous Abortion

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Medical Student Clinical Pearl

Miranda Lees, Clinical Clerk II

Dalhousie Medicine New Brunswick, Saint John

Reviewed by Dr. Mandy Peach

Case

A 21yo G3P1A1 female at 6 weeks gestation presented to the Emergency Department with an 8 hour history of vaginal bleeding and abdominal pain. The bleeding is a mixture of bright red and brown blood with no clots, and the abdominal pain is episodic cramping in her suprapubic region.

Her obstetrical history is significant for 2 prior pregnancies, the first of which was carried to term with an uncomplicated vaginal delivery, and the second of which had resulted in a spontaneous abortion at 6 weeks gestation. She is otherwise healthy. The patient noted with both prior pregnancies she had similar vaginal bleeding around 6-8 weeks gestation. She was given RhoGAM due to her Rh- blood type.

On assessment the patient appeared well with all vital signs within normal limits. On physical exam bowel sounds were present, the abdomen was tympanic to percussion, and pain on palpation was present in the patient’s suprapubic region.

 

Differential for life threatening causes of vaginal bleeding in pregnancy

<20 weeks gestation >20 weeks gestation
      ruptured ectopic pregnancy          placental abruption
       retained products of conception          placenta previa
       complication of termination          post partum hemorrhage

Other causes for vaginal bleeding to consider in pregnancy and in non-pregnant patients

Spontaneous abortion
Acute heavy menstrual bleeding
Genitourinary trauma
Uterine arteriovenous malformation
Ruptured ovarian cyst
Ovarian torsion
Pelvic Inflammatory Disease
Fibroids
Polyps
Foreign body
Coagulation disorder
Medication related
Gynecologic malignancy

 

Investigations

A βhCG was ordered to confirm pregnancy and bedside ultrasound was done to look for intrauterine pregnancy.

Transabdominal ultrasound showed the following:

The presence of a gestational sac within the uterus and a fetal heartbeat within the fetal pole confirmed a viable intrauterine pregnancy (IUP). The patient was diagnosed with threatened abortion.

 

Spontaneous Abortion-an overview

Spontaneous abortion is one of the most common complications of pregnancy, occurring in 17-22% of pregnancies2 and is defined as loss of pregnancy prior to 20 weeks gestation, occurring most often in the first trimester3. There are 3 primary causes: chromosomal abnormalities in the fetus, maternal anatomic abnormalities, and trauma.3

Risk factors for spontaneous abortion

age (below 20 and above 35)
moderate to severe bleeding (especially if passage of clots)
prior pregnancy loss
maternal comorbidities (DM, autoimmune conditions, obesity, thyroid disease)
infection (notably parvovirus, CMV and untreated syphilis)
teratogenic medications
maternal radiation exposure
maternal smoking
caffeine
alcohol use

 

Classification4

Missed abortion is characterized by an asymptomatic death of the fetus with a lack of contractions to push out the products of conception.5

Clinical presentation

Spontaneous abortion most commonly presents with vaginal bleeding and cramping, ranging from mild to severe1. However, most women with first-trimester bleeding will not undergo spontaneous abortion1. Bleeding associated with spontaneous abortion often involves passage of clots or fetal tissue, and the cramping can be constant or intermittent, often worse with passage of tissue1.

Diagnosis

Confirmation of spontaneous abortion requires pelvic ultrasound.

In patients with a prior ultrasound showing intrauterine pregnancy, diagnosis of spontaneous abortion can be made if a subsequent ultrasound shows no intrauterine pregnancy or a loss of previously-seen fetal heartbeat1.

In patients with a prior ultrasound showing intrauterine pregnancy with no fetal heartbeat, spontaneous abortion is diagnosed based on the following1:

  • A gestational sac >25mm in diameter containing no yolk sac or embryo
  • An embryo with crown rump length >7mm with no fetal cardiac activity
  • After pelvic ultrasound showing a gestational sac without a yolk sac, absence of embryo with a heartbeat in >2 weeks
  • After pelvic ultrasound showing a gestational sac with a yolk sac, absence of embryo with a heartbeat in >11 days

Case conclusion

The patient was treated with IM RhoGAM, a formal pelvic and transvaginal ultrasound was arranged for the next day, and she was discharged home. The follow-up ultrasound showed a gestational sac present in the uterus, an embryo with crown rump length of 8.1mm and the presence of a fetal heartbeat.

 

References

  1. Borhart D. Approach to the adult with vaginal bleeding in the Emergency Department. In: UptoDate, Hockberger R (Ed), UpToDate, Waltham, MA. (Accessed on October 8, 2020).
  2. Gracia C, Sammel M, Chittams J, Hummel A, Shaunik A, et al. Risk Factors for Spontaneous Abortion in Early Symptomatic First-Trimester Pregnancies. Obstetrics & Gynecology. 2005;106(5):993-999. doi 1097/01.AOG.0000183604.09922.e0.
  3. Prager, Mikes & Dalton. Pregnancy loss (miscarriage): Risk factors, etiology, clinical manisfestations, and diagnostic evaluation. In: UptoDate, Eckler (Ed), UptoDate, Waltham MA. (accessed Nov 28, 2020)
  4. Diaz. 2018. Types of Spontaneous Abortion. In: GrepMed. Image Based Medical Reference. https://www.grepmed.com/images/5425/classification-spontaneous-obstetrics-diagnosis-abortion-obgyn-types (Accessed Nov 28, 2020)
  5. Alves C, Rapp A. Spontaneous Abortion (Miscarriage) [Updated 2020 Jul 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560521/.

 

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Skin and Soft Tissue Infections: A PoCUS Guided Approach

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Medical Student Clinical Pearl – November 2020

 

Robert Hanlon

@roberthanlon12

Year: 4
DMNB Class of 2021
 

Reviewed and Edited by Dr. David Lewis

All case histories are illustrative and not based on any individual

 

Case Report

A 25yr old male presents with a 3 day history of a red swollen foot following an insect bite. He has no past medical history. On examination there is some erythema and swelling on the dorsum of the left foot. Palpation is very tender.

You are aware of recommended guidelines that advise I&D for purulent infections and decide to proceed with the procedure. Despite trying to freeze the area with lidocaine, the procedure is still painful and no pus is drained. You point to the minimal serosanguinous exudate and sheepishly suggest to the patient that the I&D was successful and that a course of antibiotics will resolve this issue.

Skin and Soft Tissue Infections: A POCUS Guided Approach

Skin and soft tissue infections (SSTIs) have a variety of potential causes, ranging in severity from mild infections like cellulitis to abscess all the way to life-threatening causes like necrotizing fasciitis.1 SSTIs are commonly encountered in the emergency department, with cellulitis and abscesses being the two most common.2 It is important to be able to recognize SSTIs and provide appropriate treatment. Abscesses require invasive management, whereas cellulitis is treated with systemic therapies; therefore, it is important to be able distinguish the different between the two types. Doing so can be difficult because of the hidden nature of abscesses. However, ultrasound can be a useful tool in establishing the presence of an abscess. This article is a review of the clinical approach and treatment for SSTIs, focusing on cellulitis and abscesses, as well as the use of ultrasound in helping to establish the diagnosis.

Approach

Clinical suspicion is the initial step in the diagnosis of SSTIs. These infections have multiple causes; therefore, obtaining a detailed history is crucial. Information about immunocompromised state, place of residence, travel, any recent trauma or surgery, previous antimicrobial use, lifestyle, hobbies, and animal bites is essential to developing an adequate differential diagnosis.3

A good understanding of the normal skin flora and common infectious organisms is key to assessing SSTIs. The most commons organisms implicated in SSTIs are Staphylococcus aureus and Streptococcus species.4-6 Methicillin resistant S. aureus (MRSA) being an important strain that has increased in prevalence in the past 20 years. Risk factors such as presence of abscess, intravenous drug use, previous MRSA status, antibiotics within 8 weeks, diabetes mellitus, and previous hospital admission within the last year increase the likelihood of the infection being cause by MRSA.4-6

Physical examination findings are crucial for establishing the presence of an SSTI; the typical criteria are a superficial lesion with the classic inflammatory findings of redness (rubor), swelling (tumor), warmth (calor), and pain (dolor).1,2,7 An abscess is defined as a fluctuant mass of puss localized and buried within a tissue, organ, or potential space; however, clinically it can be hard to determine to presence of this mass.2,7 Other associated signs and symptoms, such as crepitus, bullae, and hemorrhage, may be present upon diagnosis or may develop later during the course.2,7 Due to overlapping clinical presentations of the different SSTIs, it can be difficult to differentiate between them.

Cellulitis – No Abscess
Cellulitis – Possible Abscess
Abscess
Early Abscess

Assessment with POCUS:

Due to the similarities between different SSTI cutaneous findings and their different treatments, it is important to establish if there is an abscess present. It was common, before the introduction of ultrasound, to perform a blind needle aspiration of the infected area in order to determine the presence/absence of an abscess.8,9 However, this subjects that patient to the risks of an invasive procedure as well as pain. On the other hand, treating infection with empiric antibiotics in the presence of an unknown abscess delays drainage and allows for potential worsening of the infection.8,9

A study by Tayal et al. demonstrated that the use of ultrasound was beneficial in patients who had both low and high pretest probability for needing incision and drainage. In patients suspected of having simple cellulitis (low pretest), ultrasound was used to change management in over half of participants; establishing the need for drainage due to imaging of a fluid collection. The opposite was true in the patients suspected of having an abscess (high pretest); the study found that ultrasound was able to determine that more than half of this group did not need drainage, because of the absence of a fluid collection on imaging.10 Other studies have had similar findings, but the percent change in management was slightly lower.11

A study by Barbic et al. demonstrated that POCUS provided a rapid, non-invasive, painless, and easily repeatable test, that distinguished between abscess and cellulitis in the vast majority of cases. Their analysis concluded that POCUS had a sensitivity of 96.2% and a specificity of 82.9% in diagnosing the presence of an abscess.12 They concluded that POCUS can accurately diagnose abscess in paediatric and adult populations and is likely superior to clinical examination.12

Cobblestones

Classic finding for cellulitis (but not specific to cellulitis). There will be hyperechoic lobules of subcutaneous fat surrounded by relatively hypoechoic inflammatory fluid.13

Cobblestone – Cellulitis

Purulent Fluid Collection

Classic finding for an abscess; have a rounded shape of anechoic or hypoechoic fluid collection, and there will be surrounding areas of cobblestones from the overlying cellulitis.13 As well, there should be no color flow if doppler is applied to the area (helping to distinguish from lymph node or vessel).14

Abscess – Anechoic Collection
Possible Abscess or Lymph Node? – This is a lymph node – see below
Colour flow differentiates lymph node from abscess

Necrotizing Fasciitis

Because you do not want to miss it! Findings via ‘STAFF’; subcutaneous thickening, air, and fascial fluid.14 Note, that ultrasound does not to exclude the diagnosis. Also need clinical correlation to increase suspicion of such a serious infection.15

Necrotizing Fasciitis – STAFF

Treatment:

According to The Infectious Diseases Society of America (2014) guidelines, management of SSTIs is differentiated based on the presence/absence of purulence (i.e. abscess/fluid collection). They recommend that all purulent infections be treated with incision and drainage, with more severe infections (signs of systemic involvement) being cultured with sensitivities in order to add antibiotics to the treatment.16 Otherwise, non-purulent infections are to be treated with systemic antibiotics; the severity of the infection determining the route and choice of agent.16

Antibiotic therapy, in addition to incision and drainage of a skin abscess, is suggested for patients with any of the following:17

  • Single abscess ≥2 cm or multiple abscesses
  • Large are of surrounding cellulitis
  • Patients with immunosuppression or other comorbidities
  • Signs of systemic involvement (fever > 38°C, hypotension, or tachycardia)
  • Poor clinical response to incision and drainage alone
  • Presence of an indwelling medical device
  • High risk for adverse outcomes with endocarditis (these include a history of infective endocarditis, presence of prosthetic valve or prosthetic perivalvular material, unrepaired congenital heart defect, or valvular dysfunction in a transplanted heart)
  • High risk for transmission of aureus to others (such as in athletes or military personnel)

 

Horizon Health’s local trends recommend the following (see guideline or Spectrum app for full details)

Severity of Infection

 

 

Antibiotic

Mild

Moderate

Severe

Cephalexin 500 – 1000mg PO q6h x 5 days

ceFAZolin 2 g IV q8h x 5 days

ceFAZolin 2 g IV q8h +/- Clindamycin 900 mg IV q8h

If true beta-lactam allergy

Cefuroxime 500 mg PO BID or TID x 5 days

Clindamycin 600-900 mg IV q8h x5 days

 

If MRSA suspected

Septra 800/160 mg or 1600/320 mg PO q12h x 5 days

Vancomycin 25-30 mg/kg IV once then 15mg/kg IV q8 to q12h x 5 days

ADD Vancomycin 25-30 mg/kg IV once then 15mg/kg IV q8 to q12h

 

Some research is suggesting that POCUS can take the assessment of abscesses one step-further and impact management based on the depth and size of the fluid collection seen in imaging. Russell et al. found that abscesses less than 0.4cm below the skin surface could be effectively treated without incision and drainage.18 Another study found that patients, with skin abscesses less than or equal to 5cm in diameter, treatment with oral antibiotics in combination with incision and drainage had improved short-term outcomes compared to those patients treated with the procedure alone.18 While as mentioned above, UpToDate, suggests that antibiotics be used in single abscess greater than 2 cm in size. As well, research has found that ultrasound guided incision and drainage provides lower failure rates (less recurrent infections or multiple incisions) compared to blind incision and drainage. Likely due to better visualization of the abscess and more adequate initial drainage.19

Limitations

There are some limitations to POCUS for SSTIs: ultrasound imaging and interpretation rely on the user’s ability to obtain high-quality images in order to assess whether an abscess is present. It is important for the user to be familiar with different findings on ultrasound to guide appropriate treatment. An abscess may appear hypoechoic, hyperechoic, or anechoic (depending on tissue contents), and usually has posterior acoustic enhancement.19 Determining if it is drainable can be difficult due to this variability in imaging, and it is also quite common for early abscesses to present like cellulitis with erythema, no fluctuance, and an ultrasound that is negative for a fluid collection.20 In cases of a suspected evolving abscess, sometimes referred to as a non-ripe abscess, supportive care, including warm compresses, pain control, and close follow-up, is recommended.20 The practitioner may treat this like cellulitis; however, the patient may return with perceived failure of therapy if discharge advice does not include the possibility of of an abscess forming over time.

Abscess examples from the SJ archives

  • Drainable abscess – Note the anechoic collection with some dependent debris
  • Beard abscess – note the anechoic collection and hyperechoic hair
  • Deep abscess – swirling echoic debris = “pustulasis”
  • Small abscess – another example of “pustulasis”
  • Cellulitis – starting to coalesce but not drainable yet
  • Large abscess in groin – what are those deeper structures?
  • Femoral vessels just deep to groin abscess
  • Large abscess – thick hyperechoic pus
  • Hip incision abscess – thick hyperechoic pus
  • Ischiorectal abscess
  • Lymph node
  • Pilonidal abscess – note the hyperechoic hair
  • Cellulitis – coalesced abscess – drainable

References

  1. Moffarah AS, Al Mohajer M, Hurwitz BL, Armstrong DG. Skin and Soft Tissue Infections. Microbiol Spectr. 2016 Aug;4(4). doi: 10.1128/microbiolspec.DMIH2-0014-2015.

 

  1. Martinez, N. “Skin and Soft-Tissue Infections: Itʼs More Than Just Skin Deep.” Advanced Emergency Nursing Journal, vol. 42, no. 3, 2020, pp. 196–203.

 

  1. Cieri, B., Conway, E., Sellick, J., & Mergenhagen, K. (2019). Identification of risk factors for failure in patients with skin and soft tissue infections. The American Journal of Emergency Medicine, 37(1), 48-52.

 

  1. Borgundvaag, B., Ng, W., Rowe, B., Katz, K., Farrell, Brian, Guimont, Chantal, . . . Gregson, Dan. (2013). Prevalence of methicillin-resistant Staphylococcus aureus in skin and soft tissue infections in patients presenting to Canadian emergency departments. CJEM, 15(3), 141-160.

 

  1. Esposito, S., De Simone, G., Pan, A., Brambilla, P., Gattuso, G., Mastroianni, C., . . . Savalli, F. (2019). Epidemiology and Microbiology of Skin and Soft Tissue Infections: Preliminary Results of a National Registry. Journal of Chemotherapy (Florence), 31(1), 9-14.

 

  1. Stenstrom, R., Grafstein, E., Romney, M., Fahimi, J., Harris, D., Hunte, G., . . . Christenson, J. (2009). Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus skin and soft tissue infection in a Canadian emergency department. CJEM, 11(5), 430-8.

 

  1. Spelman, D., Baddour, LM. (2020). Cellulitis and skin abscess: Epidemiology, microbiology, clinical manifestations, and diagnosis In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Retrieved November 11, 2020. From: https://www.uptodate.com/contents/cellulitis-and-skin-abscess-epidemiology-microbiology-clinical-manifestations-and-diagnosis?search=abscess%20treatment&topicRef=110530&source=see_link#H2443336514

 

  1. Comer, Amanda B. “Point-of-Care Ultrasound for Skin and Soft Tissue Infections.” Advanced Emergency Nursing Journal, vol. 40, no. 4, 2018, pp. 296–303.

 

  1. Gaspari, R., Sanseverino, A., & Gleeson, T. (2019). Abscess Incision and Drainage With or Without Ultrasonography: A Randomized Controlled Trial. Annals of Emergency Medicine, 73(1), 1-7.

 

  1. Tayal, V., Hasan, N., Norton, H., & Tomaszewski, C. (2006). The Effect of Soft‐tissue Ultrasound on the Management of Cellulitis in the Emergency Department. Academic Emergency Medicine, 13(4), 384-388.

 

  1. Alsaawi, A., Alrajhi, K., Alshehri, A., Ababtain, A., & Alsolamy, S. (2017). Ultrasonography for the diagnosis of patients with clinically suspected skin and soft tissue infections: A systematic review of the literature. European Journal of Emergency Medicine, 24(3), 162-169.

 

  1. Barbic, D., Chenkin, J., Cho, D., Jelic, T., & Scheuermeyer, F. (2017). In patients presenting to the emergency department with skin and soft tissue infections what is the diagnostic accuracy of point-of-care ultrasonography for the diagnosis of abscess compared to the current standard of care? A systematic review and meta-analysis. BMJ Open, 7(1), E013688.

 

  1. Atkinson DP, Bowra J, Harris T, Jarman B, Lewis D, editors. Point of Care Ultrasound for Emergency Medicine and Resuscitation. Oxford University Press; 2019. pp. 140, 199-200.

 

  1. Gottlieb, M., Schmitz, G., Grock, A., & Mason, J. (2018). What to Do After You Cut: Recommendations for Abscess Management in the Emergency Setting. Annals of Emergency Medicine, 71(1), 31-33.

 

  1. Castleberg, E., Jenson, N., & Dinh, V. (2014). Diagnosis of necrotizing faciitis with bedside ultrasound: The STAFF Exam. The Western Journal of Emergency Medicine, 15(1), 111-113.

 

  1. Stevens, D., Bisno, A., Chambers, H., Dellinger, E., Goldstein, E., Gorbach, S., . . . Wade, J. (2014). Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the infectious diseases society of America. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America, 59(2), 147-159.

 

  1. Spelman, D., Baddour, LM. (2020). Cellulitis and skin abscess in adults: treatment. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. Retrieved November 11, 2020. From: https://www.uptodate.com/contents/cellulitis-and-skin-abscess-in-adults-treatment?search=abscess%20treatment&topicRef=110529&source=see_link

 

  1. Russell, F., Rutz, M., Rood, L., Mcgee, J., & Sarmiento, E. (2020). Abscess Size and Depth on Ultrasound and Association with Treatment Failure without Drainage. The Western Journal of Emergency Medicine, 21(2), 336-342.

 

  1. Gaspari, R., Sanseverino, A., & Gleeson, T. (2019). Abscess Incision and Drainage With or Without Ultrasonography: A Randomized Controlled Trial. Annals of Emergency Medicine, 73(1), 1-7.

 

  1. Thornton J, Hellmich T. Evaluation and Management of Abscesses in the Emergency Department. Emergency Medicine Reports. 2017 May 1;38(10).
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Fascia Iliaca Nerve Block

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Hip Broke? Hip Block. Use of the fascia iliaca nerve block for analgesia in hip fractures.

Resident Clinical Pearl (RCP) July 2020

Luke Edgar, BScH MD

PGY1 Family Medicine Integrated Emergency Medicine

Dalhousie Saint John

 

Reviewed by Dr. David Lewis

Background

Hip fractures are a common and painful injury diagnosed and treated in the emergency department, with elderly patients representing the majority of cases. Advanced age, comorbidities, and increased sensitivity to side effects from systemic analgesia all pose challenges to achieving adequate pain control.1,2 Additionally, NSAID use in the elderly is frequently contraindicated due renal, cardiac, and gastrointestinal comorbidities as well as drug interactions. In elderly patients, both undertreated pain and opioid analgesia can precipitate delirium.3

Regional nerve blocks for the indication of hip and femoral neck fractures have been shown to reduce pain and need for IV opiates.1 Contraindications include infection over the injection site, patient refusal, and allergy to local anesthetic. Additionally, patients at risk for compartment syndrome (such as those with a concomitant ipsilateral tibial plateau fracture) should be selected cautiously as they may not reliably have increased pain after block.4

There are three main techniques described for regional nerve blocks to provide analgesia for hip and femoral neck fractures.1

  • Fascia Iliaca Nerve Block: Insert a needle through the fascia lata and fascia iliaca, to infiltrate dilute local anesthetic into the fascial compartment which diffuses to block the femoral, lateral femoral cutaneous, and obturator nerves.
  • Femoral Nerve Block: At the level of the femoral triangle, infiltrate local anesthetic around the femoral nerve.
  • 3-in-1 Femoral Nerve Block: At the level of the femoral triangle, infiltrate local anesthetic around the femoral nerve while applying pressure distal to the injection site, encouraging local anesthetic to track superiorly to block the femoral, lateral femoral cutaneous, and obturator nerves.

Figure 1. Lower limb peripheral nerve sensory distribution.5 Circled in red are the nerves blocked using the fascia iliaca technique. Cutaneous distribution of the obturator nerve is not depicted but consists of a small area on the proximal medial thigh.

Technique

Table 1. Supplies and equipment for performing a fascia iliaca nerve block

Table 2. Steps to complete a fascia iliaca nerve block6

Table 3. One person technique  – Steps to complete a fascia iliaca nerve block

Figure 2. Video demonstrating the sonoanatomy of the right femoral triangle. From lateral to medial, femoral nerve, artery and vein (NAVel), labeled with yellow, red, and blue arrows, respectively.

Figure 3. Sonoanatomy of the right femoral triangle, transverse view for the fascia iliaca nerve block.

Figure 4. Sonoanatomy of the right femoral triangle demonstrating ultrasound-guided needle placement using an in-plane technique. Note two pops should be felt as the needle crossed the two fascial planes.

 

For a visual review of these steps and ultrasonographic landmarks, please see the following videos and webpage by EM Ottawa, 5 Minute Sono, and NYSORA:

EM Ottawa

5 Minute Sono

NYSORA

Ultrasound-Guided Fascia Iliaca Block

 

Complications

Serious complications of this procedure are rare, but present.

  • Local Anesthetic Systemic Toxicity (LAST) as a complication of inadvertent intravenous or intra arterial anesthetic injection.7
    1. Incidence is 8 – 30 in 100,0008
    2. Manifestations typically occur within 20 minutes of injection (although onset can be as late as >1 hr) and are primarily neurologic and cardiovascular in nature. Neurologic effects include perioral numbness, metallic taste, mental status change or anxiety, muscle twitches and visual changes, followed by loss of consciousness and seizure. Cardiovascular effects are hypertension and tachycardia followed by arrhythmias, bradycardia, hypotension and cardiac arrest.
    3. Treatment is with intravenous lipid emulsion therapy (Intralipid 20%) 1.5 mL/kg bolus followed by 0.25 mL/kg/min, Maximum total dose 12 mL/kg. Contact your poison control centre if you suspect LAST.
    4. Prior to performing a fascia iliaca block, confirm availability of intralipid within your department to be used in the event of this rare complication.
  • Femoral Nerve injury secondary to intrafascicular injection
    1. Incidence 2-30/100,0008
    2. Most symptoms of paresthesias, numbness, and weakness resolved after several months in the event of this complication8
  • Other complications include infection, nerve block failure, injury secondary to numbness/weakness of limb, and allergy to the local anesthetic.

 

Take Home Message

Femoral nerve blocks are recommended for hip and femoral fractures to reduce pain and opioid analgesia requirements. Given that poor pain control and opioid analgesia are risk factors for delirium in elderly patients, hip blocks may also reduce rates of delirium (further study required). A fascia iliaca block with 20 cc of 0.5% bupivacaine is a well described technique with very few contraindications. To reduce the risk of complications, these blocks should be completed using sterile technique under ultrasound guidance with the help of an assistant. Hip broke? Hip block.

 

 

References

  • Ritcey B, Pageau P, Woo M, Perry J. Regional Nerve Blocks For Hip and Femoral Neck Fractures in the Emergency Department: A Systematic Review. CJEM 2015;18(1):37-47.
  • Hwang U, Richardson LD, Sonuyi TO, Morrison RS. The effect of emergency department crowding on the management of pain in older adults with hip fractures. J Am Geriatr Soc. 2006;54(2):270-5.
  • Morrison RS, Magaziner J, Gilbert M, et al. Relationship between pain and opioid analgesics on the development of delirium following hip fracture. J Gerontol A Biol Sci Med Sci 2003;58(1):76-81.
  • Erak M, EM Ottawa Grand Rounds. Ah, that feels better! The Use of Nerve Blocks in the ED. 2016. https://emottawablog.com/2016/10/ah-that-feels-better-the-use-of-nerve-blocks-in-the-ed/. Accessed July 25, 2020.
  • Gray H. 1918. Nerve supply of the leg. Anatomy of the Human Body. Image retrieved from https://en.wikipedia.org/wiki/Nerve_supply_of_the_human_leg. Accessed July 24, 2020
  • Woo M. How to perform the Ultrasound Guided Femoral Nerve Block. EM Ottawa. 2018. https://youtu.be/_OugsPA4rxY Accessed July 25, 2020.
  • Warren L, Pak A. Local anesthetic systemic toxicity. UpToDate. 2019. uptodate.com/contents/local-anesthetic-systemic-toxicity. Accessed July 25, 2019.
  • Helman, A, Morgenstern, J, Spiegel, R, Lee, J. Regional Nerve Blocks for Hip Fractures. Emergency Medicine Cases. August, 2018. https://emergencymedicinecases.com/regional-nerve-blocks-hip-fractures/. Accessed July 25, 2020.
  • Haines L, Dickman E, Ayvazyan S, et al. Ultrasound-guided fascia iliaca compartment block for hip fractures in the emergency department. J of Ultrasound in Emergency Medicine 2012;43(4):692-697.

 

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Lung PoCUS – Podcast

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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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