Topics in this EM Quick Hits podcast

Tahara Bhate introducing QI corner! (00:37)

Hans Rosenberg & Michael Gottlieb on the evidence around ED diagnosis and management of skin abscesses (9:49)

Anand Swaminathan on what the oxygen saturation monitor can tell you besides oxygen saturation (16:45)

Sarah Reid on how to pick up infantile spasms and prevent poor neurologic outcomes (23:01)

Elisha Targonsky on battle of the ED rate control medications for rapid atrial fibrillation (27:44)

Podcast production, editing and sound design by Anton Helman

Podcast content, written summary & blog post by Anton Helman and Sarah Reid

Cite this podcast as: Helman, A. Swaminathan, A. Reid, S. Rosenberg, H. Gottlieb, M. Bhate, T. Targonsky, E. EM Quick Hits 37 – Introducing QI Corner, Skin Abscess, O2 Sat Monitor Pearls, Infantile Spasms, Atrial Fibrillation Rate Control. Emergency Medicine Cases. April, 2022. [date].

Introducing… QI corner!

  • Analysis of every missed diagnosis should be broken down into patient, health care providers and systems factors
  • Risk factor assessment for serious life or limb threatening diagnoses should be considered carefully (eg. IVDU is a risk factor for occult life-threatening infection)
  • Lack of social supports, drug intoxication and mental health concerns can make patient evaluation challenging and are risk factors for poor outcome
  • Multiple return visits are a red flag for serious pathology
  • Systems should ensure that previous health care provider notes, including ones in the past 24hrs that may not appear in EMR yet, are readily available for review
  • Peer support workers for marginalized populations may help facilitate assessment and management of these patients and prevent ‘left without being seen’ and ‘left against medical advice’ both of which are associated with poor outcomes

Ottawa M&M Model : A Guide to Enhancing Morbidity and Mortality Rounds

  1. DiGiorgio, A. M., Stein, R., Morrow, K. D., Robichaux, J. M., Crutcher, C. L., II, & Tender, G. C. (2019). The increasing frequency of intravenous drug abuse–associated spinal epidural abscesses: a case series, Neurosurgical Focus FOC46(1), E4. Retrieved Apr 12, 2022, from

Evidence around ED diagnosis and management of skin abscesses and PoCUS

  • While the accuracy of clinical assessment alone is quite good for skin abscesses over all (specificity 94.7%, sensitivity 84.2%), when the ED physician is unsure of the diagnosis the accuracy drops precipitously (specificity 42%, sensitivity 43.7%)
  • While the overall accuracy of PoCUS is similar to clinical assessment (94.6% sensitive and 85.4% specific) for cases that are clinically unlear PoCUS is far better (specificity 76.9%, sensitivity 91.9%); it is this latter group that warrants consideration for PoCUS
  • PoCUS can aid incision and drainage in a multitude of ways:
    • determining size of abscess,
    • help identify small/superficial abscesses that may not require drainage,
    • best location for incision, identification of lateral margins to facilitate loop drainage,
    • assess nearby vascular structures to avoid,
    • distinguish abscess from aneurysm/pseudoaneurysm/enlarged lymph node,
    • identify deep/complicated abscess and/or signs of necrotizing fasciitis that may require referral for extensive surgery

EM Cases Episode 109 Skin & Soft Tissue Infections – Cellulitis, Skin Abscesses & Necrotizing Fasciitis

5 Minute Sono on Differentiating Cellulitis from Skin Abscess

  1. Gottlieb M, Sundaram T, Kim DJ, Olszynski P. Just the facts: point-of-care ultrasound for skin and soft-tissue abscesses. CJEM. 2021 Sep;23(5):597-600. doi: 10.1007/s43678-021-00132-9. Epub 2021 Apr 22.
  2. Marin JR, Dean AJ, Bilker WB, Panebianco NL, Brown NJ, Alpern ER. Emergency ultrasound-assisted examination of skin and soft tissue infections in the pediatric emergency department. Acad Emerg Med. 2013;20(6):545–53.

The oxygen saturation monitor multitasker – more that just oxygen saturation

  • There is a racial bias inherent in the oxygen saturation monitor device; oxygen saturation is overestimated in individuals with darker skin; the true oxygen saturation in individuals with darker skin is lower than the oxygen saturation monitor reading
  • Analysis of the oxygen saturation monitor waveform can reveal both both heart rate and peripheral vascular perfusion; a robust waveform indicates that cardiac contractility is adequate enough to produce a peripheral pulse/pulsatile flow at the location of the monitor
  • Perfusion index (0.3-20) is a ratio between pulsatile and nonpulsatile blood flow, a marker of the strength of the pulse at the location of the monitor that requires adequate cardiac output and low enough peripheral resistance; the oxygen waveform is lost at <0.5 perfusion index which is usually the result of  low cardiac output and/or severe peripheral vasoconstriction

Pitfall: a common pitfall is assume that lack of oxygen saturation monitor waveform is the result of poor oxygenation rather than of poor peripheral vascular perfusion; rather than moving the monitor to a different location and cranking the oxygen delivery, consider ways of improving peripheral perfusion

EM: RAP: Racial Bias in Pulse Oximetry Measurement 
REBEL EM: Racial Bias with Pulse Oximetry

  1. Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Racial Bias in Pulse Oximetry Measurement. N Engl J Med. 2020 Dec 17;383(25):2477-2478.
  2. Middleton PM, Retter A, Henry JA. Pulse oximeter waveform analysis as a measure of circulatory status. Crit Care. 2001;5(Suppl 1):P152.

Infantile spasms – easy to misdiagnose and early diagnosis and treatment improves outcomes

  • Infantile spasms are a severe form of epilepsy that usually presents at 4-7 months of age characterised by a triad of: spasms, characteristic EEG pattern (hypsarrhythmia) and developmental delay that is easy to miss on initial presentation as the signs can be subtle; it is often misdiagnosed as reflux or infantile colic or exaggerated startle reflex
  • The reason it is important to pick this up in the ED is because prognosis improves with early identification of underlying cause and early initiation of treatment
  • Typically, spasm characterized by symmetric bowing at the waist with extension and elevation of the arms and tonic extension of the legs – a bit like an ab crunch, lasting a few seconds, often in clusters, often as baby is falling asleep or waking, and often with crying before and after, often with development
  • Other forms – extensor/flexor/mixed spasms, subtle head bobbing
  • +/- eye deviation, nystagmus, altered respirations, brief LOC
  • Causes (in 2/3 of cases): hypoxemic ischemic encephalopathy, stroke, trauma, chromosomal abnormalities, metabolic disorders, tuberous sclerosis (look for skin findings!)

Video showing various examples of  infantile spasms

  1. Farooq O, Kirmani A, Agarwal N, et al. 6-month-old boy with strange body movements. Peds in Review 35(4) April 2014 e20-e24.
  2. Hancock_EC, Osborne_JP, Edwards_SW. Treatment of infantile spasms. Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD001770.
  3. Wilmhurs JM, Ibekwe RC, O’Callaghan FJK, Epileptic spasms – 175 years on: Trying to teach an old dog new tricks. Seizure 44(2017) 81-86.

Rate control medications for rapid atrial fibrillation

  • First, assess if the patient’s heart rate is rapid due to primary dysrhythmia or due to a secondary cause/underlying medical condition, and consider treating the secondary cause rather than employing rate control
  • Indications for rate control include patients who are stable with a high risk for stroke, or low risk for stroke if onset 24-48 hrs and ≥2  CHADS-65 criteria, consider rate control per patient and physician preference (eg. older patients who are minimally symptomatic)
  • Patients are poor at identifying the time of onset of atrial fibrillation (only 64% of the time, and less so in older patients)
  • Ca-channel blockers and beta-blockers are first line to achieve a heart rate <100 at rest and <110 ambulating
  • A 2021 meta-analysis comparing diltiazem vs metoprolol showed that use of diltiazem resulted in lower heart rates at 5, 10, 15 minutes and final heart rate
  • If patient already taking oral Ca-channel or beta-blocker, choose same drug group first
  • Avoid Ca-channel blockers if acute heart failure or known LV dysfunction
  • If difficulty achieving target rate
    • consider the other first-line agent but experts suggest waiting ≥30 minutes between administration to avoid drug potential interaction and further dysrhythmias
    • IV digoxin 0.25mg IV x 1
    • IV Mg 2-4.5g is controversial as an adjunctive medication; a metaanalysis suggests efficacy; some experts recommend reserving it as a second line agent in patients with known hypomagnesemia, alcohol use disorder or malnutrition despite one study showing no difference in the response to Mg therapy between Mg deficient and nondeficient patients at 15, 30 or 60 minutes after therapy
  • Ca-channel blocker dose: Diltiazem 0.25 mg/kg IV over 10 minutes; repeat q15-20 min at 0.35 mg/kg up to 3 doses; some evidence to suggest that 10mg IV diltiazem as effective as 0.25mg/kg IV, so consider starting with 10mg IV, especially in frail older patients or those with non-ideal hemodynamics
    • Start 30-60 mg orally within 30 mins of effective IV rate control
    • Discharge on 30-60mg qid or Extended Release 120-240 mg once daily
  • Beta-blocker dose: Metoprolol 2.5-5 mg IV over 2 minutes, repeat q15-20 min up to 3 doses
    • Start 25-50 mg orally within 30 mins of effective IV rate control
    • Discharge on 25-50 mg bid

Pitfall: a common pitfall is to neglect giving oral rate control medications soon after IV medications have achieved rate control and prescribing oral rate control medications for home, only to have the patient rebound to rapid atrial fibrillation

  • For patients in acute heart failure or non-ideal hemodynamics consider digoxin 0.25mg IV x 1 first line in consultation with cardiology; onset is slow and beware patients with renal failure
  • Patients with atrial flutter and more difficult to rate control with medications than atrial fibrillation and often require electrical cardioversion

CAEP checklist atrial fibrillation

  1. Jafri SH, Xu J, Warsi I, Cerecedo-Lopez CD. Diltiazem versus metoprolol for the management of atrial fibrillation: A systematic review and meta-analysis. Am J Emerg Med. 2021 Oct;48:323-327.
  2. Fromm C, Suau SJ, Cohen V, Likourezos A, Jellinek-Cohen S, Rose J, Marshall J. Diltiazem vs. Metoprolol in the Management of Atrial Fibrillation or Flutter with Rapid Ventricular Rate in the Emergency Department. J Emerg Med. 2015 Aug;49(2):175-82.
  3. Bishop J Jr, Akram G. Diltiazem Dosing Strategies in the Management of Atrial Fibrillation With Rapid Ventricular Rate. Cureus. 2021 Oct 16;13(10):e18829.
  4. Stiell IG, de Wit K, Scheuermeyer FX, Vadeboncoeur A, Angaran P, Eagles D, Graham ID, Atzema CL, Archambault PM, Tebbenham T, McRae AD, Cheung WJ, Parkash R, Deyell MW, Baril G, Mann R, Sahsi R, Upadhye S, Brown E, Brinkhurst J, Chabot C, Skanes A. 2021 CAEP Acute Atrial Fibrillation/Flutter Best Practices Checklist. CJEM. 2021 Sep;23(5):604-610.
  5. Bouida W, et al. Low dose magnesium sulfate versus high dose in the early management of rapid atrial fibrillation: randomised controlled double blind study. Acad Emerg Med. 2018 Jul 19.
  6. Onalan O, Crystal E, Daoulah A, Lau C, Crystal A, Lashevsky I. Meta-analysis of magnesium therapy for the acute management of rapid atrial fibrillation. Am J Cardiol. 2007;99(12):1726-1732.
  7. Eray O, Akça S, Pekdemir M, Eray E, Cete Y, Oktay C. Magnesium efficacy in magnesium deficient and nondeficient patients with rapid ventricular response atrial fibrillation. Eur J Emerg Med. 2000 Dec;7(4):287-90.

None of the authors have any conflicts of interest to declare