Topics in this EM Quick Hits podcast

Justin Hensley & Aaron Billin on wilderness medicine (0:38)

Elisha Targonsky on bowel prep hyponatremia (Best of University of Toronto EM) (14:23)

Brit Long on identification of non-convulsive status epilepticus (21:18)

Andrew Petrosoniak on Morel Lavallee lesions (29:24)

Jess McLaren on approach to the ECG in the paced patient (36:35)

Matt Poyner on loan repayment vs investing (41:22)

Podcast production, editing and sound design by Anton Helman

Written summary & blog post by Hanna Jalali, Andrew Petrosoniak and Brit Long.

Edited by Anton Helman, February 2023

Cite this podcast as: Helman, A. Hensley, J. Billin, A. Targonsky, E. Long, B. Petrosoniak, A. McLaren, J. Poyner, M. EM Quick Hits 46 – Wilderness Medicine, Bowel Prep Hyponatremia, Non-Convulsive Status Epilepticus, Morel Lavallee Lesions, Pacemaker ECGs, Loans vs Investing. Emergency Medicine Cases. February, 2023. Accessed May 27, 2024.

Bowel prep hyponatremia

Best of University of Toronto EM

  • Severe hyponatremia causing coma and/or seizure after bowel prep such as polyethylene glycol for colonoscopy has been reported in the literature.
  • The incident of hyponatremia and elevated ADH levels is up to 7.5% in patients post-colonoscopy.
  • Causes are multifactorial:
    • Stress from procedure/prep causing non-osmotic ADH release, water retention
    • GI volume losses
    • Dietary restriction, low solute intake
    • Massive free water intake, dilutional hyponatremia
  • Risk factors:
    • Large volume intake over short time
    • More frequent in women
    • Concomitant use of thiazide diuretics
    • Concomitant hypothyroidism
  • Treatment of severe hyponatremia with coma/seizure includes hypertonic saline, given as a bolus of 100-150mL of fluid over 5-10 minutes (repeat x 1-2 prn), stopping all other IV fluids, insertion of foley catheter to monitor urine output, frequent checks of serum electrolytes being careful not to increase serum sodium by more than 6mmol/L over 6 hours for severely symptomatic patients and aiming to increase sodium by 4-6mmol/L over first 2 hours, and no more than 10mmol/L over 24 hours
  • Resist treatment in patients with mildly impaired mental status, or chronic hyponatremia as rapid correction can lead to osmotic demyelination syndrome.

Episode 60 Emergency Management of Hyponatremia

  1. Adrogué HJ, Tucker BM, Madias NE. Diagnosis and Management of Hyponatremia: A Review. JAMA. 2022 Jul 19;328(3):280-291.
  2. Windpessl, M., Schwarz, C. & Wallner, M. “Bowel prep hyponatremia“ – a state of acute water intoxication facilitated by low dietary solute intake: case report and literature review. BMC Nephrol 18, 54 (2017).
  3. Reumkens A, van der Zander Q, Winkens B, Bogie R, Bakker CM, Sanduleanu S, Masclee AAM. Electrolyte disturbances after bowel preparation for colonoscopy: Systematic review and meta-analysis. Dig Endosc. 2022 Jul;34(5):913-926.
  4. Costelha J, Dias R, Teixeira C, Aragão I. Hyponatremic Coma after Bowel Preparation. Eur J Case Rep Intern Med. 2019 Aug 26;6(9):001217.
  5. Rasheed T, Alvi H, Shaikh MA, Ali FS, Zuberi BF, Subhan W. Frequency of hyponatremia caused by sodium picosulfate solution when used as a bowel cleansing agent for colonoscopy. Pak J Med Sci. 2020 Nov-Dec;36(7):1651-1654.

Non-Convulsive Status Epilepticus

  • Non-convulsive status epilepticus (NCSE) is a change in cognition or mental status with no significant convulsive activity and accounts for 47% of all status epilepticus.
  • EEG definition of NCSE is abnormalities on EEG for 10 continuous minutes or intermittent seizure activity for >20% of an hour
  • It is important have NCSE on our differential for alteration in mental status and treat appropriately if suspected.
  • Consider NCSE in patients with:
    • altered mental status and abnormal ocular movements, lip smacking or subtle muscle twitches
    • medication history with anti-epileptic
    • patients that were seizing, treated, and are having a prolonged post-ictal period
    • unexplained altered mental status with no findings on ED testing
  • Causes:
    • Most common: inadequately treated convulsive status epilepticus
    • Acute brain injury
    • Structural brain lesion
    • Infection
    • Encephalopathy
    • Chronic alcohol use
    • Medications
  • Presentation *a careful ocular exam showing subtle abnormalities is often the clue to NCSE
    • Most common: change in mental status
    • Abnormality in ocular movement (i.e. eye deviation, nystagmus, eyelid twitching. Specificity of altered mental status and ocular movement abnormality is 85% for NCSE).
    • Changes in speech (aphasia): occurs in 15% of cases
    • Motor twitching of face or hands (e.g. lip smacking)
    • Other findings: hypertension, diaphoresis, flushing, catatonia, repeated crying or laughing
  • Key ED diagnostic clue: a trial of benzodiazepines with an improvement in LOA is suggestive of NCSE

Best Case Ever 22 Non-Convulsive Status Epilepticus

  1. Trinka E, Cock H, Hesdorffer D, et al. A definition and classification of status epilepticus—report of the ILAE Task Force on Classification of Status Epilepticus. Epilepsia. 2015;56:1515-1523.
  2. Hirsch LJ, Fong MWK, Leitinger M, et al. American clinical neurophysiology society’s standardized critical care EEG terminology: 2021 version. J Clin Neurophysiol. 2021;38:1-29.
  3. Leitinger M, Beniczky S, Rohracher A, et al. Salzburg consensus criteria for non-convulsive status epilepticus—approach to clinical application. Epilepsy Behav. 2015;49:158-163.
  4. Wang X, Yang F, Chen B, Jiang W. Non-convulsive seizures and non-convulsive status epilepticus in neuro-intensive care unit. Acta Neurol Scand. 2022 Dec;146(6):752-760.
  5. Kinney MO, Craig JJ, Kaplan PW. Non-convulsive status epilepticus: mimics and chameleons. Pract Neurol. 2018 Aug;18(4):291-305.
  6. Bravo P, Vaddiparti A, Hirsch LJ. Pharmacotherapy for nonconvulsive seizures and nonconvulsive status epilepticus. Drugs. 2021;81:749-770.

Morel Lavallee Lesions – closed de-gloving injury of the pelvis or leg

  • Morel Lavallee lesions are uncommon closed de-gloving injury of the pelvis or leg that is usually caused by high-energy trauma to the soft tissues resulting in detachment of the subcutaneous tissues from the deep fascia that typically present hours to days to weeks following high energy trauma
  • Diagnosis is typically suspected clinically but confirmed using one of U/S, CT or MRI
  • Clinical findings include fluctuant mass, edema, and tenderness at affected site with possibility of overlying cellulitis from initial dermal injury
  • Missed diagnosis may result in pressure necrosis, compartment syndrome, infection (including necrotizing fasciitis), chronic collections
  • Management ranges from conservative treatment with compression to minimally invasive to an open surgical approach.

  1. Ten-year incidence and treatment outcomes of closed degloving injuries (Morel-Lavallee lesions) in a level 1 trauma centre. J Med Imaging Radiat Oncol 2022 Jul 29.
  2. Practical Review of the Comprehensive Management of Morel-Lavallée Lesions. Plast Reconstr Surg Glob Open. 2021 Oct 7;9(10):e3850.
  3. Morel-Lavallée Lesions: A Diagnostic and Clinical Dilemma. 2022 Aug 15;14(8):e28038.

Approach to pacemaker ECGs – the PACER mnemonic

P: Pacemaker spikes – are they present and appropriate?

  • Normal pacemaker spikes can be appropriately absent with normal intrinsic rhythm or appropriately present either intermittently or with full pacing.

A: awareness. Is the pacemaker aware of the intrinsic rhythm?

  • Normal pacemaker will sense intrinsic rhythm and inhibit pacing or will sense lack of intrinsic rhythm and deliver appropriate pacing.
  • Abnormalities are oversensing (responding to stimuli other than intrinsic rhythm). This leads to Another abnormality may be undersensing (not recognizing intrinsic rhythm). This leads to overpacing.

C: capture. Do pacemaker spikes trigger appropriate depolarization?

  • In normal capture every spike triggers a beat, in failure to capture pacing spikes fails to trigger a beat

E: ECG. Does the rest of the 12-lead ECG reveal any other problems?

  • Is there evidence of further QRS widening due to hyperkalemia which can lead to pacemaker malfunction?
  • OMI can be identified using the Modified Sgarbossa criteria. This include concordant ST elevation, concordant ST depression in anterior leads, or discordance defined as ST elevation >25% of preceding S wave.

R: rest of patient. Are their complications from pacemaker insertion, or emergencies unrelated to the pacemaker?

For ECG examples and deep dive… ECG Cases 36 – PACER mnemonic for Approach to Pacemaker Patients

  1. Glikson M, Nilsen JC, Kronbord MB, et al. 2021 ESC guidelines on cardiac pacing and cardiac resynchronization therapy: developed by the Task Force on cardiac pacing and cardiac resynchronization therapy of the European Society of Cardiology (ESC) with the special contribution of the European Heart Rhythm Association (EHRA). Eur Heart J Sept 2021;42(35):3427-3520
  2. Cardall TY, Chan TC, Brady WJ, et al. Permanent cardiac pacemakers: issues relevant to the emerg physician, part I. J of Emerg Med 1999;17(3):479-489
  3. Cardall TY, Brady WJ, Chan TC et al. Permanent cardiac pacemakers: issues relevant to the emerg physician, part II. J of Emerg Med 1999;17(4):697-709
  4. Barold SS, Herweg B. The effect of hyperkalemia on cardiac rhythm devices. Europace 2014;16:467-476
  5. Dodd KW, Zvosec DL, Hart MA, et al. Electrocardiographic diagnosis of acute coronary occlusion myocardial infarction in ventricular paced rhythm using the Modified Sgarbossa Criteria. Ann Emerg Med 2021 Oct;78(4):517-529
  6. Gunaseelan R, Sasikumar M, Aswin K, et al. Memory T-waves, a rare cause of T-wave inversion in the emergency department. J Emerg Trauma Shock 2020 Oct-Dec;13(4):312-316

None of the authors have any conflicts of interest to declare