Review Question - QID 109858

This patient is presenting with altered mental status, increased anion gap metabolic acidosis, and calcium oxalate crystals in the urine, suggesting the diagnosis of ethylene glycol poisoning. This form of poisoning should be treated with fomepizole.

Ethylene glycol poisoning (common with antifreeze ingestion) can present with inebriation, somnolence, and acute kidney injury characterized by flank pain, hematuria, and oliguria. Similar to methanol ingestion, the patient will have an increased anion gap metabolic acidosis and a high osmolar gap. Ethylene glycol is converted to oxalic acid which can cause the precipitation of calcium oxalate stones and kidney failure. Initial management involves the administration of fomepizole to prevent further conversion of ethylene glycol and subsequent dialysis.

Kruse reviews the evidence regarding the treatment and outcomes of patients with methanol and ethylene glycol poisoning. He discusses how early identification and treatment can be lifesaving even in the case of large ingestions. He recommends early treatment of these conditions.

Figure/Illustration A is a urinalysis that shows envelope-shaped crystals (red circles). These calcium oxalate crystals are associated with ethylene glycol poisoning.

Incorrect Answers:
Answer 1: Ampicillin-sulbactam and vancomycin or any broad-spectrum antibiotics can be used if the presentation is suspicious for septic shock. Although sepsis can cause altered mental status, the patient does not meet additional quick Sequential Organ Failure Assessment (SOFA) criteria: respiratory rate greater than or equal to 22/min and/or systolic blood pressure less than or equal to 100 mmHg.

Answer 3: Flumazenil can be used for benzodiazepine overdose. Symptoms of benzodiazepine overdose include somnolence, ataxia, and respiratory depression. Flumazenil should not be used in a patient with long-term benzodiazepine use as it can precipitate seizures. It is also generally not used first-line as the mainstay of care is observation and supportive therapy.

Answer 4: Supportive therapy is not sufficient for this patient. He requires fomepizole and subsequent dialysis to prevent the production and promote the removal of toxic metabolites.

Answer 5: Thiamine is part of the treatment for alcohol intoxication causing Wernicke-Korsakoff syndrome. The triad of symptoms for Wernicke encephalopathy is confusion, ataxia, and ophthalmoplegia. Korsakoff psychosis is characterized by personality changes, memory loss, confabulation, and hallucinations.

Bullet Summary:
The most appropriate initial management for ethylene glycol toxicity is fomepizole followed by dialysis.