EM Boards Survival Guide: Toxicology 1

Author: Alex Koyfman, MD (@EMHighAK) // Edited by: Brit Long, MD (@long_brit)

emDocs will be providing you with regular tips and must-know items for EM boards and inservice. Each post will feature several key takeaways on a specific organ system or subject. Today…toxicology.

Boards Must-Knows:

1) Charcoal: Does NOT bind toxic alcohols, inorganic ions (lithium, potassium), hydrocarbons, heavy metals (iron, lead, zinc, mercury). Avoid if concerned about aspiration risk, altered mental status, intestinal obstruction. Recommended ratio of 10:1 charcoal to xenobiotic; often 50 g is given.

– WikEM

– CCC

2) Toxins that are dialyzable: I STUMBLED (isopropyl alcohol / isoniazid; salicylates; theophylline / tylenol; uremia; methanol / metformin; barbiturate; lithium; ethylene glycol; depakote / dabigatran).

– Tox and the Hound

– WikEM

3) Anion gap: Know how to calculate (https://www.mdcalc.com/anion-gap). Known DDx for anion gap metabolic acidosis => MUDPILES CAT or KULT.

– WikEM

– CCC

4) Osmolar gap: Know how to calculate (https://www.mdcalc.com/serum-osmolality-osmolarity).

– WikEM

– CCC

5) Toxin/antidote: Make a chart (board/inservice exams love this). Some favorites: acetaminophen, salicylate, TCA, methanol / ethylene glycol, digoxin, isoniazid, CO, CN, B-blocker / CCB, iron, organophosphate, etc.

– WikEM

– LIFTL

6) Ethanol: Metabolism defined by zero order kinetics (approx. 20 mg/dL/hr). Alcoholic ketoacidosis: binge drinking then stop, need dextrose, look for why they stopped. Wernicke’s: know triad, treat with high-dose thiamine; if missed progresses to Korsakoff’s (antero/retrograde amnesia, confabulation). Know all flavors of alcohol withdrawal and treatment options. Consider toxic alcohol ingestion.

– WikEM – toxicity

– WikEM – Wernicke-Korsakoff

– WikEM Alcohol Ketoacidosis

– ToxCard – Ketoacidosis

– WikEM – Withdrawal

– Emergency Medicine Cases – Withdrawal

– FOAMCast – Withdrawal

7) Ethylene glycol: Why is my “alcohol intoxicated” patient not getting any better? Large AGMA. Antifreeze. Oxalic + glycolic acids => renal insufficiency. Treat with fomepizole, pyridoxine, hemodialysis.

– LIFTL

– Emergency Medicine Cases

– EM@3AM

– WikEM

8) Methanol: Why is my “alcohol intoxicated” patient not getting any better? Large AGMA. Windshield wiper fluid, moonshine. Formic acid => blind. Treat with fomepizole, folic acid, hemodialysis.

– LIFTL

– WikEM

– Emergency Medicine Cases

– EM@3AM

9) Isopropanol: “Significantly intoxicated” with fruity odor. Metabolized to acetone, thus no AGMA. Treatment usually supportive; rarely hemodialysis is needed.

– LIFTL

– WikEM

10) Acetaminophen: Know toxic dose (think 150 mg/kg), as well as acute and chronic ingestion differences. Know stages of toxicity; note: acetaminophen is a silent killer. Know application and pitfalls of Rumack-Mathew nomogram. Check 4-hour level: if single ingestion + known time. Treat w/ NAC; the earlier the better but ok to start later.

– ToxCard

– WikEM

– LIFTL