This protocol applies to patients with confirmed or strongly suspected ethylene glycol poisoning who meet defined laboratory and clinical entry criteria — including a documented plasma ethylene glycol concentration, a raised serum osmol gap, or a combination of acid-base and urinary findings — and in whom initial fomepizole-based antidote therapy has not normalised the key endpoints.
Fomepizole is preferred over ethanol in patients with altered consciousness, ingestion of multiple CNS-depressant substances, active hepatic disease, relative contraindication to ethanol, or critically ill anion-gap metabolic acidosis of unknown aetiology.
Intravenous fomepizole antidote therapy (loading dose followed by maintenance dosing) did not achieve the required endpoints: serum ethylene glycol undetectable or <20 mg/dL, patient asymptomatic, and normal arterial pH. This protocol is the escalation step taken after that failure.
Documented plasma ethylene glycol concentration >20 mg/dL.
Documented recent (hours) history of ingesting toxic amounts of ethylene glycol and osmol gap >10 mosm/L.
History or strong clinical suspicion of ethylene glycol poisoning and at least two of the following criteria: A. Arterial pH <7.3. B. Serum bicarbonate <20 mEq/L. C. Osmol gap >10 mosm/L. D. Urinary oxalate crystals present.
The administration of fomepizole to patients with ethylene glycol poisoning is preferred to the use of ethanol in the following situations: ingestion of multiple substances with CNS depressant activity; any alteration of consciousness; the lack of intensive care beds; critically ill patient with an anion gap–metabolic acidosis of unknown etiology and potential exposure to ethylene glycol; the lack of laboratory support to monitor ethanol administration; and the presence of contraindications to the use of ethanol.
Fomepizole should not be administered to patients with known hypersensitivity reactions to fomepizole or to other pyrazole compounds.
Hemodialysis should be considered for the following conditions: deteriorating vital signs despite intensive supportive care, significant metabolic acidosis (<7.25–7.30), and renal failure or electrolyte imbalances unresponsive to conventional therapy.
Hemodialysis effectively removes both ethylene glycol and its toxic metabolites.
The dosing interval of fomepizole should be reduced to every 4 hours during hemodialysis.
Alternately, an infusion of fomepizole 1–1.5 mg/kg/h during dialysis is sufficient to maintain therapeutic concentrations of fomepizole.
The traditional endpoint for dialysis is an undetectable serum ethylene glycol concentration or an EG <20 mg/dL and the disappearance of acid-base abnormalities and signs of systemic toxicity.
Correction of the metabolic acidosis (anion gap) and the osmol gap are adequate endpoints for dialysis, particularly when the patient is receiving fomepizole or ethanol and the serum ethylene glycol and/or glycolate concentrations are unavailable.
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