Ethylene Glycol Poisoning

Aka: Ethylene Glycol Poisoning, Ingestion of Ethylene Glycol, Ethylene Glycol, Ethylene Alcohol, Ethylene Dihydrate, Glycol Alcohol, Monoethylene Glycol, Antifreeze Fluid, De-icing solution

1. Pathophysiology
   1. Ethylene Glycol found in antifreeze and de-icer
      1. Rapid absorption from Stomach and Small Intestine
   2. Toxicity results at doses >1.0 ml/kg
      1. Ethylene Glycol causes CNS depression (Alcohol-like)
      2. Glycolic Acid (metabolite) effects
         1. Metabolic Acidosis
         2. Renal Failure
      3. Oxalic acid (metabolite) effects
         1. Calcium oxalate crystal deposition
2. Symptoms and Signs
   1. Stage I: CNS Effects (peak 6-12 hours after ingestion)
      1. Confusion
      2. Ataxia
      3. Slurred speech
      4. Hallucinations
   2. Stage II: Cardiopulmonary Effects (onset 12-36 hours)
      1. Nausea or Vomiting
      2. Hyperventilation
      3. Muscle Tetany or Seizures (Hypocalcemia)
      4. Hypertension
      5. Tachycardia
   3. Renal Effects (ensue within 24 to 72 hours)
      1. Oliguria or anuria (Acute Renal Failure)
3. Labs
   1. Initial labs
      1. Arterial Blood Gas
      2. Chemistry panel
      3. Serum Osmolality
      4. Urinalysis
   2. Lab findings suggestive of Ethylene Glycol ingestion
      1. Serum Osmolar Gap >10 mOsm/kg H2O
      2. Metabolic Acidosis with increased Anion Gap
      3. Hypocalcemia
      4. Calcium oxalate crystals seen on urine microscopy
         1. Needle-shaped monohydrate form or
         2. Envelope-shaped dihydrate form
   3. Other tests to consider
      1. Serum Ethylene Glycol test
         1. Specific, but expensive and not readily available
         2. Does not predict prognosis
         3. Level >20 mg/dl indicates antidote below
      2. Woods lamp exam of urine
         1. Antifreeze contains Fluorescein
4. Management: Antidotes
   1. Indications
      1. Serum Ethylene Glycol level >20 mg/dl or
      2. Suspected Ethylene Glycol intake and 2 or more:
         1. Arterial pH <7.3
         2. Serum bicarbonate <20 meq/L
         3. Osmolal Gap >10 mOsm/kg H2O
         4. Calcium oxalate crystals in urine
   2. Mechanism
      1. Blocks Alcohol dehydrogenase
      2. Prevents metabolite (Glycolic Acid) formation
   3. Agents
      1. Fomepizole (Antizol)
         1. New agent specific for Alcohol dehydrogenase
         2. Load: 15 mg/kg
         3. Next: 10 mg/kg q12 hours for 4 doses
         4. Maintenance: 15 mg/kg q12 hours
         5. End point: Ethylene Glycol <20 mg/dl
      2. Ethanol
         1. Alternative if Fomepizole not available
         2. Requires blood alchohol level 100 to 150 mg/dl
         3. Dose: 10% Ethanol diluted in 5% dextrose
            1. Load: 8-10 ml/kg over 30 minutes
            2. Maintenance: 1.4 to 2.0 ml/kg/hour
5. Management: Hemodialysis Indications
   1. Deteriorating condition despite maximal support
   2. Metabolic Acidosis with serum pH <7.25
   3. Acute Renal Failure refractory to other measures
   4. Serum electrolyte imbalance refractory
   5. Fomepizole not available and serum level >50 mg/dl
      1. Serum level does not otherwise indicate dialysis
6. Management: Other mesaures
   1. Sodium Bicarbonate
      1. Benefits
         1. Corrects Metabolic Acidosis
         2. Inhibits calcium oxalate crystal deposition
         3. Increases Glycolic Acid excretion
      2. Technique
         1. Keep Urine pH >7.0
   2. Vitamin supplementation
      1. Pyridoxine Supplementation
      2. Thiamine 100 mg IV qd
   3. Unhelpful measures
      1. Syrup of Ipecac is not effective
      2. Gastric Lavage is not effective
      3. Activated Charcoal is not effective
7. Prognosis
   1. Fatal if severe case not treated within 24-36 hours
8. References
   1. Leiken (1995) Poisoning and Toxicology, p. 925-6
   2. Barceloux (1999) J Toxicol Clin Toxicol 37:537-60
   3. Scalley (2002) Am Fam Physician 66(5):807-12