Isopropyl alcohol toxicity

Background

• Main component of rubbing alcohol
• Hallmark is osmolar gap without acidosis
  • Metabolized to acetone, not to an acid
• Takes 30-60min for acetone to appear in blood; 3hr to appear in urine
• Lethal Dose: 4-8 g/kg or 250mL in average adult

Clinical Features

• CNS depression
  • Similar to ETOH intoxication, but longer-lasting
  • Usually peak in first hour of ingestion
• GI
  • N/V / abd pain / hemorrhagic gastritis
• Respiratory depression
• Hypotension
• Hypoglycemia (in malnourished pts)

Differential Diagnosis

• Ethanol Toxicity
• Methanol Toxicity
• Ethylene Glycol Toxicity
• Starvation ketoacidosis
• Diabetic Ketoacidosis
• Inborn errors of metabolism
• Salicylate Toxicity
• Acetone ingestion

Diagnosis

Work-Up

• Fingerstick glucose
• Complete metabolic panel
• Serum ketones
• Serum Osmolality
• Uinarlysis
• VBG
• Aspirin/Tylenol levels
• ECG
• Serum isopropyl alcohol level (if available)
• Total CK

Evaluation

• Osmolal gap > 10; see Osmolal or Osmolar Gap
• Absence of anion gap
• Absence of metabolic acidosis
• Absence of serum beta hydroxybutyrate
• Presence of serum and urine ketones
  • Consider other diagnosis if absent 2hr after ingestion
• Creatinine may be falsely elevated d/t acetone interference w/ laboratory measurement of Cr

Treatment

• Mechanical ventilation may be necessary
• Hypotension
  • Usually responsive to IVF; pressors may be necessary
• Hemodialysis
  • Consider for:
    • Hypotension refractory to conventional therapy
    • Isopropanol level >400

Contraindicated

• Fomepizole
  • Metabolite, acetone, is no more toxic than the parent compound
  • Use may lead to prolonged CNS toxicity
• GI decontamination
  • Activated charcoal ineffective (absorbed too quickly)

Disposition

• Consider discharge if asymptomatic x 4-6hr