Question Of The Day #78

This patient presents to the Emergency department from a party with slurred speech and somnolence after drinking homemade alcohol.  On exam, his vital signs and glucose are normal, he is nonresponsive to pain, and he has a GCS of 3 (normal GCS is 15).  He is intubated due to his inability to protect his airway and risk for aspiration.  Intubation is an important first step in managing this patient.

Altered mental status has a broad differential diagnosis, including intracranial bleeding, stroke, post-ictal state, hypoglycemia, electrolyte abnormalities, other metabolic causes, infectious etiologies, toxicological causes, and many other conditions.  The immediate evaluation and treatment of this patient should focus on the ‘ABCs’, or any abnormality in the airway, breathing, and circulation.  Any rapidly correctable causes of altered mental status, like hypoxia, hypoglycemia, or hyperthermia, should be addressed appropriately at this stage (i.e., supplemental oxygen, intubation, IV dextrose, body cooling). 

Paracetamol (APAP) overdose (Choice A) is often accompanied with little to no symptoms in the first 24hours.  Later in the ingestion timeline, liver failure and its associated sequalae can occur if no antidote is given.  The symptoms exhibited by the patient do not correlate with APAP overdose.  Opioid overdose (Choice D) can cause severely depressed mental status as seen in this patient.  However, opioid overdose also has decreased respiratory rate, pinpoint pupils, and sometimes associated bradycardia or hypotension.  This patient has normal vital signs and normal pupil size.  This patient ingested some type of alcohol at the party, but it is unclear if it is ethanol or a toxic alcohol (i.e., methanol, ethylene glycol).  Both ethanol and methanol ingestion (Choice B) can cause similar exam findings of depressed mental status as in this patient.  Other features of toxic alcohol ingestion include vision changes (methanol), hemorrhagic gastritis (isopropyl alcohol), coma, seizures, and hyperventilation (respiratory compensation for severe acidosis).  Ethanol and many of the toxic alcohols will cause an increased anion gap metabolic acidosis with an increased osmolar gap.  Helpful tests to differentiate ethanol from a toxic alcohol are serum levels of ethanol and serum toxic alcohol levels (if available).  A somnolent, intoxicated-appearing patient with a negative ethanol level should raise suspicion for toxic alcohol poisoning.  Urine studies may also show oxalate crystals in ethylene glycol ingestion. 

Since ethanol is not a listed choice and laboratory studies are not provided, methanol ingestion (Choice B) is the most likely cause of this patient’s symptoms.  Fomepizole (Choice C) is an intravenous medication that inhibits the alcohol dehydrogenase enzyme.  Fomepizole is the antidote to toxic alcohols by slowing the production of dangerous toxic alcohol metabolites.  The correct answer is Choice B.