Continuing on the theme of Toxic Alcohols (osmolal gap, ethylene glycol), this Paucis Verbis card focuses on methanol toxicity. Useful are the American Academy of Clinical Toxicologists recommendations on when to administer an antidote (fomipezole) and when to perform hemodialysis. I redrew the flowchart based on what’s relevant to the ED in the initial stages.
A patient re-presents to the Emergency Department with a foreign body sensation in his heel after stepping on a broken window. Despite a negative xray and bedside ultrasound yesterday, the patient still believes that a small foreign body is still in there. You are unable to find a foreign body despite excising the overlying skin with a scalpel and exploring with forceps.
Following last week’s Paucis Verbis card on calculating the osmolal gap, here is the first installment of the Toxic Alcohols cards. First up — ethylene glycol. There are useful American Academy of Clinical Toxicologists recommendations on when to administer an antidote (fomipezole) and when to perform hemodialysis.
Here’s a quick review of the metabolism of the different toxic alcohols. The parent compounds for ethylene glycol and methanol are innocuous and the metabolites are toxic.
Adapted from [1-3]
Go to ALiEM (PV) Cards for more resources.
See Dr. Leon Gussow’s great review on The Poison Review and tips of a recent Annals of EM4 paper on identifying a small subset of patients with ethylene glycol who did well despite NOT receiving hemodialysis.
A 3 month old baby presents with distal erythema and swelling of one of her toes. A hair tourniquet is identified. Typically one can try manually unwrapping the tourniquet using forceps, but often only part of the tourniquet can be removed. The distal toe remains swollen and erythematous with delayed capillary refill.
As demonstrated by the image above, it can be difficult to identify the hair because of the edema and the thin nature of the hair (especially if the same as the patient’s skin color). In a 2006 review of hair tourniquets in the Annals of Plastic Surgery, they recommend incising down to the bone along the lateral edge of the digit to ensure tourniquet release. It seems a bit aggressive…
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We often talk about calculating the anion gap in the evaluation of patients. What about the osmolal gap? When do you calculate this? What’s the differential diagnosis for an increased gap?
I recently came upon a nice 2011 review in the American Journal of Kidney Disease called “Approach to the evaluation of a patient with an increased serum osmolal gap and high-anion-gap metabolic acidosis”. It’s always nice to revisit and review this concept. You’ll always learn something new. For instance, I didn’t know that salicylates cause anion gaps as well as osmolal gaps.
So don’t forget to calculate an osmolal gap for patients with an unexplained metabolic acidosis anion gap.
Adapted from [1]
Go to ALiEM Cards for more resources.
Marking the surface anatomy for procedures can significantly increase your chances for success, such as for lumbar punctures and central lines. I can never seem to find surgical skin markers.
Sometimes classic techniques need to be revisited, especially when I get new photos from the collective readership. Let’s review a painless way to remove beads from the ear canal. You can’t exactly have the patient’s provider blow in the other ear to expulse the bead, similar to a nasal foreign body…