Emergency Medicine

Scombroid Poisoning

When there is too much histamine in fish, people should beware.

The Scombroid family of fish includes tuna and mackerel. When stored improperly, there can be too much histamine, which is not degraded by cooking. This causes symptoms of histamine excess, such as urticaria and all the usual culprits of unwellness.

The clinical diagnosis is based on history of multiple people being affected, rather than a single person with an allergy, as well as the redness of the presentation. Theoretically, the fish’s histamine can be measured. Histamine metabolites should show in the urine.

An antihistamine medication is the answer to this issue, such as the H1 antagonist diphenhydramine.

References

  1. Sicari V, Patel P, Zabbo CP. Diphenhydramine. [Updated 2025 Mar 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526010/.
  2. Liddiard, S., Nickson, C. and Nickson, S.L. (2024). Scombroid Poisoning. [online] Life in the Fast Lane • LITFL. Available at: https://litfl.com/scombroid-poisoning/.

The Poetry Of Pareidolia

Pareidolia is the tendency to see visual meaning where there isn’t any, like a face in toast, because humans evolved to detect patterns. Here is the most poetic pareidolia entry ever.

A 20-year-old woman presented to our emergency department after a cliff-jumping adventure went awry. The ultrasound of the aorta was benign, but a “Darth Vader” sign found off the reflection of the spine was no Jedi mind trick. The ability to detect an aneurysm is insignificant next to the power of the Force!

Pareidolia is a phenomenon of recognizing patterns, shapes and familiar objects — often faces — where they do not actually exist. There are several well-known examples in popular culture, including most recently a perception of Vladimir Putin’s resemblance in a flock of birds, the image of Jesus on toast or the “Face on Mars” captured by the Viking 1 orbiter. Examples achieving popular notoriety are found in medicine as well, particularly with diagnostic imaging.

Pareidolia is recognized in humans as young as eight months old. Compared with other types of illusion, pareidolia is unique in how the illusion often becomes more intense with increased attention to it. Similar neural processes trigger pareidolic illusions and visual hallucinations, which has led to speculation that pareidolia represents a susceptibility to visual hallucinations. Conversely, other studies have shown that the right temporal lobe discriminates between real and illusory faces but is highly suggestible, consistent with a more benign prognosis.

Could there be more to pareidolia than sheer entertainment value? Simply put, pareidolia is perceiving a meaningful pattern in meaningless noise. In medicine, we learn to detect illness patterns in the noise of nonspecific signs and symptoms.

Bibliography

Baylis, J., & Ting, D. K. (2015). Pareidolia and clinical reasoning: the pattern awakens. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 187(18), 1364. https://doi.org/10.1503/cmaj.151079

Hypokalaemia ECG Changes

There are three major ones, plus more!

  1. ST depression
  2. Flattened T waves
  3. Abnormally prominent U waves

The way to remember this is that, in line with the subpar nature of hypokalaemia, everything is weak and low!

ST depression is a depression, so it is low.

The T waves have low amplitude, so they too are low.

The dip of the letter U, as in U waves, looks like the minimum point of a parabola, so it’s also low.

Conveniently, it all follows an alphabetical pattern: ST, T, U.

References

  1. ECG Learning Center. (n.d.). 12. Nice Seeing “U” Again. [online] Available at: https://ecg.utah.edu/lesson/12 [Accessed 4 Jul. 2018].
  2. Burns, E. (n.d.). Hypokalaemia. [online] LITFL. Available at: https://lifeinthefastlane.com/ecg-library/basics/hypokalaemia/ [Accessed 4 Jul. 2018].

Treatment Options For Hyperkalaemia

If hyperkalaemia is indeed real and not caused by haemolysis or a bad sample, treatment can be appropriate. It’s urgent if there are ECG changes.

  • Calcium gluconate
    • Stops membrane depolarisation
    • Does not reduce the serum potassium level
  • Sodium bicarbonate IV
    • To treat metabolic acidosis, which can be a potential underlying cause
      • Potassium moves out of cells because it exchanges with hydrogen ions
  • Insulin and glucose IV
    • Use short-acting insulin
    • To promote uptake of potassium into cells
    • Effective in kidney failure
  • Polystyrene resin orally
    • Removes potassium from bowel lumen by exchanging it for sodium or calcium
    • Comes in sodium or calcium varieties, called Resonium
      • Sodium type adds to sodium load in body
      • Calcium type avoids this but is unsuitable in hypercalcaemia
  • Dialysis
    • Last resort if extreme hyperkalaemia and nothing else works

Of course, the underlying cause should be treated; if it’s hypoaldosteronism, such as from adrenal insufficiency, corticosteroids should be given. If it’s volume depletion, that should be corrected. If the hyperkalaemia is caused by a medication, that medication should be ceased.

References

  1. Electrolyte abnormalities. In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited (eTG November 2017 edition); 2017 Nov.
  2. acutecaretesting.org. (2013). On the relationship between potassium and acid-base balance. [online] Available at: https://acutecaretesting.org/en/journal-scans/on-the-relationship-between-potassium-and-acid-base-balance [Accessed 17 Feb. 2018].

Contraindications To Lumbar Puncture

A lumbar puncture is a procedure that involving drawing out cerebrospinal fluid, fondly known as CSF. For example, it can be used to check CSF for immune cells and glucose levels in suspected meningitis.

Lumbar puncture is considered an invasive procedure. But even with that aside, it’s not appropriate for everyone. That is, it does not suit all patients.

Contraindications to lumbar puncture are:

  • Skin infection at the lumbar puncture site
  • Uncorrected coagulopathy
  • Increased intracranial pressure
  • Trauma to the spinal cord

References

  1. Queen’s University School of Medicine. (n.d.). Contraindications. [online] Available at: https://meds.queensu.ca/central/assets/modules/lumbar_puncture/contraindications.html [Accessed 2 Feb. 2018].

American Compact Disc

Colles and Smith fractures are both fractures of the distal radius.

Colles fracture

  • Dorsal angulation of the fractured fragment
  • Memory aid: CD

Smith fracture

  • Volar angulation of the fractured fragment
    • Volar means palmar
  • Memory aid: VS almost looks like US, which is quite American

And that’s how an American CD is made.

References

  1. Luijkx, T. and Desai, P. (2018). Colles fracture. [online] Radiopaedia. Available at: https://radiopaedia.org/articles/colles-fracture [Accessed 15 Jan. 2018].
  2. Luijkx, T. and Gaillard, F. (2018). Smith fracture. [online] Radiopaedia. Available at: https://radiopaedia.org/articles/smith-fracture [Accessed 15 Jan. 2018].

Heart Failure Treatment Acronyms

Medications don’t cure people. Acronyms do.

Well, maybe medications do a little bit.

Maybe.

Anyway, here’s how to remember how to treat acute heart failure in an examination setting.

LMNOP

  • Lasix
  • Morphine
  • Nitrates
  • Oxygen
  • Position

POND

  • Position and positive pressure ventilation
  • Oxygen
  • Nitrates
  • Diuretics

References

  1. SOCMOB Blog. (2017). Evidence Based Management of Acute Heart Failure: Forget LMNOP, think POND! – SOCMOB Blog. [online] Available at: http://socmob.org/2013/04/evidence-based-management-of-acute-heart-failure-forget-lmnop-think-pond/ [Accessed 24 Dec. 2017].
  2. Time of Care. (2017). LMNOP – For Congestion in Acute Decompensated Hear Failure. [online] Available at: https://www.timeofcare.com/lmnop-for-congestion-in-acute-decompensated-hear-failure/ [Accessed 24 Dec. 2017].