Topics in this EM Quick Hits podcast

Anand Swaminathan on approach to emergency management of Ludwig’s angina (00:39)

Anna MacDonald on transient monocular visual loss (09:20)

Mike Misch on workup of suspected PE in pregnancy (16:15)

Natalie May on pediatric nasal foreign bodies tips and tricks (23:20)

David Juurlink on sulfamethoxazole/trimethoprim drug interactions (29:00)

Justin Morgenstern on airway management options in cardiac arrest (35:50)

Podcast production, editing and sound design by Anton Helman

Podcast content, written summary & blog post by Anand Swaminathan, Natalie May, Anton Helman, Justin Morgenstern, Michael Misch, Anna MacDonald and David Juurlink , edited by Anton Helman

Cite this podcast as: Helman, A. Swaminathan, A. Morgenstern, J. Juurlink, D. May, N. MacDonald, A. Misch, M. EM Quick Hits 5 -Ludwig’s Angina, Transient Monocular Vision Loss, PE Workup in Pregnancy, Pediatric Nasal Foreign Bodies, Sulfamethoxazole/Trimethoprim Interactions, Airway Management in Cardiac Arrest. Emergency Medicine Cases. June, 2019. [date].

Ludwig’s Angina Emergency Management – Approach, Airway, Imaging

  • Allow the Ludwig’s patient to be in their position of comfort to help maintain a patent airway
  • These patients will have anatomically challenging airways. If you can, get the patient to the OR for definitive management and let the airway be controlled there with someone present who can do a tracheostomy if necessary. Call your surgeon early.
  • If immediate control of the airway in necessary, consider awake fiberoptic nasotracheal intubation after thorough topicalization +/- low dose ketamine. A blind nasotracheal approach is a reasonable alernative if you don’t have fiberoptics. Avoid paralytics if the patient is breathing spontaneously and prepare for a cricothyrotomy.
  • Initiate IV broad spectrum antibiotics including coverage for anaerobes and consider IV dexamethasone as well as nebulized epinephrine
  • Ludwig’s angina is a clinical diagnosis and does not require advanced imaging. Do not delay the patient going to the OR or getting transferred to a hospital with a surgeon for a CT. Remember that the patient has to be comfortable lying flat to get a CT.

Transient Monocular Vision Loss (TMVL)

Causes of TMVL

  • Non-inflammatory vascular causes
    1. Emboli (TIA of the eye)
    2. Ocular ischaemia
    3. Impending Central Retinal Vein Occlusion (CRVO)
  • Giant cell arteritis (temporal arteritis)
  • Retinal migraine (VL should be followed by headache within 60 mins)
  • Optic neuritis – Uhthoff’s phenomenon
  • Local globe/orbit/lid problems (e.g. glaucoma, orbitopathies, hyphema, dry eyes)

Clinical Pearls

  • TMVL from emboli is very difficult to differentiate clinically from GCA. Have a low threshold to do ESR and CRP in patients over 50.
  • Much more likely to be arterial ischaemia if:
    1. Clear description of sudden onset and specific duration of vision loss
    2. Description of curtain coming down or up over field of vision

  1. Dattilo, M., Newman, N. J., & Biousse, V. (2018). Acute retinal arterial ischemia. Annals of Eye Science, 3(6), 28–28.
  2. Feroze, K. B., & O’Rourke, M. C. (2019). Transient Loss Of Vision. StatPearls Publishing.
  3. Marx, J. A., & Rosen, P. (2014). Rosen’s emergency medicine: concepts and clinical practice. 8th ed. Philadelphia, PA: Elsevier/Saunders.
  4. Petzold, A., Islam, N., Hu, H.-H., & Plant, G. T. (2013). Embolic and nonembolic transient monocular visual field loss: a clinicopathologic review. Survey of Ophthalmology, 58(1), 42–62.
  5. Pula, J., Yuen, C., Kattah, J., & Kwan, K. (2016). Update on the evaluation of transient vision loss. Clinical Ophthalmology, 297–7.

D-dimer in the Work-up of Pulmonary Embolism in Pregnancy

  • If a pregnant with a suspicion for pulmonary embolism is low or intermediate risk using Geneva Score then it appears safe to use D-Dimer as a rule-out test using the standard cut off of 500 while decreasing imaging rates.
  • Based on the Artemis trial, it appears safe to use a D-Dimer cutoff of 1000 if the patient is also YEARS negative – that is: no sign of DVT, no hemoptysis and the provider does not think PE is the most likely diagnosis.

  1. Righini M, Robert-ebadi H, Elias A, et al. Diagnosis of Pulmonary Embolism During Pregnancy: A Multicenter Prospective Management Outcome Study. Ann Intern Med. 2018;169(11):766-773.
  2. Van der Pol LM, Tromeur C, Bistervels IM, et al. Pregnancy-Adapted YEARS Algorithm for Diagnosis of Suspected Pulmonary Embolism. N Engl J Med. 2019;380(12):1139-1149.
  3. Van der Hulle T, Cheung WY, Kooij S, et al. Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study. Lancet. 2017;390(10091):289-297.

Management of Pediatric Nasal Foreign Bodies: Tips and Tricks

  • Children 5 years of age or older can often coordinate their breathing adequately so that by occluding the contralateral nostril, the child may be able to simply blow the foreign body out
  • An alternative to classic “parent’s kiss” technique is  to use a bag-valve-mask or high flow oxygen using standard oxygen tubing inserted into the contralateral nare
  • For flat, incompletely occlusive foreign bodies you may be able to pass a lubricated, small (eg size 5-8F) Foley catheter beyond the foreign body before inflating the balloon and gently pulling back on the catheter to bring the foreign body out with it
  • There is a significant failure rate with procedural sedation and forceps removal in the ED after other methods have failed, so consider ENT consultation for patients in whom the above methods have failed

Sulfamethoxazole-Trimethoprim Drug Interactions

  • Trimethoprim and spironolactone taken together increase the risk for hyperkalemia with a clear association between trimethoprim and sudden cardiac death
  • There is a 12 fold increased risk in hospital admission for hyperkalemia in elderly patients taking trimethoprim in combination with spironolactone compared to amoxicillin in combination with spironolactone
  • There is a 7 fold increased risk in hospital admission for hyperkalemia in elderly patients taking trimethoprim in combination with ACE inhibitors or ARBs compared to amoxicillin in combination with ACE inhibitors or ARBs
  • How to avoid life threatening hyperkalemia with trimethoprim?
    1. Use a different antibiotic, if appropriate
    2. Hold ACEi/ARB/spironolactone, if appropriate
    3. Limit dose/duration of trimethoprim
    4. Monitor potassium closely during treatment
    5. Be extra cautious in CKD and diabetic patients
  • Avoid sulfamethoxazole-trimethoprim in patients taking methotrexate as it may contribute to methotrexate anti-folate effect leading to mucositis
  • Avoid sulfamethoxazole-trimethoprim in patients taking warfarin as the drug interaction may increase INR leading to hemorrhage
  • Avoid sulfamethoxazole-trimethoprim in patients taking sulfonylureas as the drug interaction may cause hypoglycemia with a relative risk of hospitalization 5-6 fold higher compared to amoxicillin

  1. Antoniou T, Hollands S, Macdonald EM, et al. Trimethoprim-sulfamethoxazole and risk of sudden death among patients taking spironolactone. CMAJ. 2015;187(4):E138-E143.
  2. Antoniou T, Gomes T, Juurlink DN, Loutfy MR, Glazier RH, Mamdani MM. Trimethoprim-sulfamethoxazole-induced hyperkalemia in patients receiving inhibitors of the renin-angiotensin system: a population-based study. Arch Intern Med. 2010;170(12):1045-9.
  3. Antoniou T, Gomes T, Mamdani MM, et al. Trimethoprim-sulfamethoxazole induced hyperkalaemia in elderly patients receiving spironolactone: nested case-control study. BMJ. 2011;343:d5228.
  4. Velázquez H, Perazella MA, Wright FS, Ellison DH. Renal mechanism of trimethoprim-induced hyperkalemia. Ann Intern Med. 1993;119(4):296-301.
  5. Ho JM, Juurlink DN. Considerations when prescribing trimethoprim-sulfamethoxazole. CMAJ. 2011;183(16):1851-8.
  6. Hamid M, Lashari B, Ahsan I, Micaily I, Sarwar U, Crocetti J. A deadly prescription: combination of methotrexate and trimethoprim-sulfamethoxazole. J Community Hosp Intern Med Perspect. 2018;8(3):149-151.
  7. Fischer HD, Juurlink DN, Mamdani MM, Kopp A, Laupacis A. Hemorrhage during warfarin therapy associated with cotrimoxazole and other urinary tract anti-infective agents: a population-based study. Arch Intern Med. 2010;170(7):617-21.
  8. Juurlink DN, Mamdani M, Kopp A, Laupacis A, Redelmeier DA. Drug-drug interactions among elderly patients hospitalized for drug toxicity. JAMA. 2003;289(13):1652-8.

Airway Options in Cardiac Arrest – LMA for all?

Three large RCTs examined prehospital airway management in adult out of hospital nontraumatic cardiac arrest in 2018.

  • Benger 2018 demonstrated no functional outcome difference between intubation and and LMA
  • Jabre 2018 demonstrated no neurologic outcome difference between intubation and BVM
  • Wang 2018 demonstrated improved 72 hr survival with a laryngeal airway over intubation

Bottom Line expert opinion: the most efficient way ensure a patent airway in most cardiac arrest patients is using an LMA combined with waveform capnography.

1.Benger JR, Kirby K, Black S, et al. Effect of a Strategy of a Supraglottic Airway Device vs Tracheal Intubation During Out-of-Hospital Cardiac Arrest on Functional Outcome: The AIRWAYS-2 Randomized Clinical Trial. JAMA. 2018; 320(8):779-791.

More info:

2. Jabre P, Penaloza A, Pinero D, et al. Effect of Bag-Mask Ventilation vs Endotracheal Intubation During Cardiopulmonary Resuscitation on Neurological Outcome After Out-of-Hospital Cardiorespiratory Arrest: A Randomized Clinical Trial. JAMA. 2018; 319(8):779-787.

More info:

3. Wang HE, Schmicker RH, Daya MR, et al. Effect of a Strategy of Initial Laryngeal Tube Insertion vs Endotracheal Intubation on 72-Hour Survival in Adults With Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial. JAMA. 2018; 320(8):769-778.

More info:

None of the authors have any conflicts of interest to declare