HPI

• 50 yo male presents 1 hour after accidental ingestion of windshield washer fluid that he had stored in a gatorade bottle
• Pt became acutely dizzy and nauseated and had a near syncopal event shortly after ingestion
• Began vomiting en-route with EMS

PE

• VS: T 97.2 HR 70 BP 138/80 RR 16 Pox 98%
• Pt actively vomiting reddish tinged watery fluid
• Oropharynx is clear 
• Lungs clear
• Abd soft and nontender

What's in windshield washer fluid anyways? Is it bad to ingest?

• Windshield washer fluids variably contain methanol or ethylene glycol, as these alcohols have a much lower freezing point than water (so the fluid doesn't freeze while in the reservoir of a car during the winter)
• Yes, it is very bad to ingest methanol or ethylene glycol: they are collectively referred to as two of the "toxic alcohols" and can be deadly in relatively small ingestions

Lab results

• Na 144 K 4.4 Cl 109 CO2 18 BUN 10 Cr 0.90 Glucose 114
• Measured serum osmolality: 385
• Osmolar gap: 86
• VBG: pH 7.24 PC02 27 HCO3 13  --> Metabolic acidosis with appropriate respiratory compensation
• Methanol and ethylene glycol levels: Send out to reference lab

Dx and Critical Actions

• Toxic alcohol ingestion: the patient has a markedly elevated osmolar gap indicating the presence of unmeasured osmotically active solute (presumptively the toxic alcohol)
• The patient also exhibits the first signs of toxicity with a metabolic acidosis as the toxic alcohols are metabolized 
• Critical therapy: initiation of therapy with fomepizole a potent inhibitor of alcohol dehydrogenase, the enzyme responsible for metabolism of methanl and ethylene glycol to their (toxic) metabolites
• Folinic acid may also help to enhance metabolism of formate (the toxic metabolite of methanol)
• Sodium bicarbonate infusion may help to treat severe metabolic acidosis
• Severe toxicity with profound acidosis warrants emergent hemodialysis

Case resolution 

• The patient's repeat blood gas and serum chemistries demonstrated resolution of metabolic acidosis 
• Serum methanol levels returned at 280 ng/dL (markedly elevated)
• Patient was admitted to general medical floors for q12 fomepizole and serial methanol levels

Pearls

• In cases of clear or strongly suspected toxic alcohol ingestion, do not delay administration of fomepizole --> this drug binds to alcohol dehydrogenase with X1000 affinity of methanol and protects the patient while confirmatory lab tests are pending
• Don't forget the administration of folinic acid
• Treat mild/moderate metabolic acidosis with bicarbonate infusions
• Consider emergent hemodialysis for severely poisoned patients in the setting of severe metabolic acidosis