Toxicity, Ethylene Glycol Treatment & Management

• Ascertain as much specific information regarding the identity of the ingested substance as possible.
• If possible, obtain the bottle or container that held the ingested substance. Interviewing persons present at the site of the ingestion may be helpful in this regard.
• Obtain intravenous access and administer crystalloid infusions.
• Monitor cardiac function and determine blood dextrose level.
• Airway management is a priority because of the risk of aspiration.
• Evidence-based guidelines on out-of-hospital management of ethylene glycol poisoning are available from the American Association of Poison Control Centers.^[5]

Rapidly evaluate patients who present with signs, symptoms, or history of toxic alcohol ingestion; determine serum osmolal gap. The prehospital (EMS) personnel often can provide important details regarding the identity of the chemical(s) involved and the clinical characteristics of the patient.

• Obtain intravenous access and laboratory specimens.
• Measure levels of electrolytes, calcium, and magnesium, especially in patients with alcoholism because alcohol is a cofactor in oxalate metabolism.
• Administer crystalloids at 250-500 mL/h IV initially to enhance renal clearance of the toxin and to limit deposition of oxalates in the renal cortices.
• Administer bicarbonate to correct severe acidosis (pH level ≤ 7.2).
• Pyridoxine and thiamine are cofactors in ethylene glycol metabolism and may be administered parenterally. Place symptomatic patients in a monitored setting.
• An ECG may be useful in patients with arrhythmias that may result from hypocalcemia.
• Foley catheterization is usually indicated for patients with altered mental status to monitor urinary output and to allow serial examination of urine for crystals or fluorescence.
• If the serum osmolal gap is not zero, begin antidotal therapy empirically while awaiting confirmation. This is performed with either fomepizole (4-MP) or ethyl alcohol. The latter is usually administered intravenously but may be administered orally in remote settings where emergency hospital care is not immediately available.
• Treatment of patients with suspected ethylene glycol intoxication is indicated in any of the following 3 circumstances^[6] :

  • The plasma level of ethylene glycol is 20 mg/dL or more.
  • The history of recent ethylene glycol ingestion is definite, and the osmolal gap is 10 mOsm/L or more.
  • A history or suspicion of ethylene glycol intoxication and at least 2 of the following are present:
    • Arterial pH level is less than 7.3.
    • Serum bicarbonate level is less than 20 mg/dL.
    • Osmol gap is greater than 10 mOsm/L.
    • Urinary oxalate crystals are present.
• Fomepizole (4-MP [Antizol]) is a convenient antidotal therapy for treatment of ethylene glycol or methanol intoxication. Many emergency departments have adopted routine use of this agent for cases of suspected toxic alcohol poisoning.^[7] Fomepizole is administered with a loading dose and twice-daily intravenous dosing.^[8]

  • Fomepizole is advantageous because it does not depress the patient's mental status or airway and needs to be administered only every 12 hours. The main drawback of fomepizole is the cost, which can total thousands of dollars. Because this agent is so expensive, clinicians should check its availability at their institution and discuss the plan for use of this antidote, especially for empiric treatment of cases in which the cause of acidosis is unknown.
  • Fomepizole is equally efficacious for the treatment of methanol intoxication but does not cause any alteration in mental status, hypoglycemia, or respiratory depression.
  • Fomepizole received US Food and Drug Administration (FDA) approval in December 1997.
  • The availability of timely results of laboratory tests can be a problem. Weigh the benefits, risks, and costs of each therapeutical intervention at the treating institution.
• If fomepizole is not used, oral or parenteral ethanol loading can be initiated as a temporizing measure while awaiting test results.

  • A loading dose of ethanol is administered based on body weight, followed by infusion to maintain a serum level of approximately 100 mg/dL.
  • Carefully calculate the loading dose and administration of ethanol antidote to prevent excessive administration. Overly aggressive ethanol administration has reportedly caused cases of apnea that required intubation and mechanical ventilation.
  • When administering ethanol, determine glucose levels by fingerstick collection at regular intervals and confirm with laboratory analysis to detect the hypoglycemia occasionally associated with ethanol therapy.
• Most patients with ethylene glycol toxicity require monitoring in an ICU setting.^[9]
• Hemodialysis is used to treat metabolic acidosis or to prevent renal insufficiency.^[10]

  • Early in the intoxication, the toxin is present as the parent compound, ethylene glycol. As time passes, toxic metabolites accumulate and the patient develops metabolic acidosis. Eventually, oxalate is deposited in the kidney and elsewhere; renal insufficiency may ensue. Once any of these manifestations occurs, antidotal therapy alone (used to block alcohol dehydrogenase with ethanol or 4-MP) is insufficient to treat the poisoning.
  • Alcohol dehydrogenase–blocking therapy must be accompanied by dialysis to remove the metabolites in these cases. Consulting a nephrologist early in the intoxication is prudent to facilitate the timely initiation of dialysis to these patients. Delays may result in renal failure or other severe complications.
  • Some clinicians have suggested that effective blockade of alcohol dehydrogenase may permit the treatment of ethylene glycol intoxication without dialysis.^[11]
• Consultation of a poison center may be obtained anywhere in the United States and Puerto Rico by calling 1-800-222-1222.

If dialysis is considered, consult a nephrologist as early as possible to allow timely treatment of patients with toxic metabolite accumulation. Antidotal therapy is inadequate by itself in these circumstances, and dialysis should be performed as soon as possible. Consult a poison control center or a medical toxicologist for assistance in management options. The telephone number for certified poison centers anywhere in the United States and Puerto Rico is 1-800-222-1222.