UMEM Educational Pearls

Title: Extracorporeal Treatment Strategies for Acute Methanol Poisoning (When to Dialyze)

Keywords: Methanol, toxicology, methanol toxicity, critical care (PubMed Search)

Posted: 1/20/2015 by John Greenwood, MD (Updated: 1/30/2015)
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Extracorporeal Treatment Strategies for Acute Methanol Poisoning (When to Dialyze)

Methanol toxicity is classically included in the differential for the intoxicated patient presenting to the ED. Add a negative EtOH level, anion/osmolar gap, blindness and you have yourself a slam dunk diagnosis. The goal is to stop the liver from metabolizing methanol to formic acid. Outside of fomepizole (or old school ethanol therapy), dialysis is often discussed, but when should you actually get the nephrologist on the phone?

This month the Extracorporeal Treatments in Poisoning Workgroup released a systematic review and consensus statement to help clinicians decide when to pull the HD trigger. Their suggestions are below.

When to start HD:

Neurologic dysfunction: Coma, seizures, new vision deficits
Metabolic acidosis: blood pH ≤7.15 or persistent metabolic acidosis despite adequate supportive measures & antidotes
Serum anion gap higher than 24 mmol/L
Serum methanol concentration:
- > 700 mg/L (21.8 mmol/L) if fomepizole therapy is given
- > 600 mg/L or 18.7 mmol/L if ethanol treatment is given
- > 500 mg/L or 15.6 mmol/L in the absence of an alcohol dehydrogenase blocker

Which Modality: Intermittent HD (IHD) should be used over continuous renal replacement therapies (CRRT), as you can clear the toxin faster with higher HD flows.

When to stop HD: Extracorporeal treatment can be terminated when the methanol concentration is less than 200 mg/L or 6.2 mmol/L and a clinical improvement is observed.

Bottom Line: Consider early hemodialysis in most patients presenting with methanol toxicity. Clinical exam and routine lab testing will likely provide enough information to determine the need for IHD, but specific methanol levels can be helpful to guide adjunctive treatment options.

Reference

Roberts DM, Yates C, Megarbane B, et al. Recommendations for the Role of Extracorporeal Treatments in the Management of Acute Methanol Poisoning: A Systematic Review and Consensus Statement. Crit Care Med. 2015;43(2):461-472.

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