Environmental Medicine Integrating a Missing Element into Medical Education (1995) / Chapter Skim
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Case Study 14: Ethylene/Propylene Glycol Toxicity
Case Study 14: Ethylene/Propylene Glycol Toxicity
Pages 349-371
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From page 349... ...
Propylene glycol, which is much less toxic than ethylene glycol, is metabolized to compounds that are normal constituents of the citric acid cycle. No health effects have been reported in persons chronically exposed to levels of ethylene or propylene glycolfound in the environment.
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From page 350... ...
What would you include in each patient's problem list? What is the differential diagnosis for an anion gap metabolic acidosis?
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From page 351... ...
A discussion of ethylene glycol follows; discussion of propylene glycol begins on page 18. Ethylene Glycol Exposure Pathways O Antifreeze, which can contain up to 95% ethylene glycol, is the most common source of ethylene glycol overexposure.
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From page 352... ...
O Because of its low vapor pressure and poor skin absorption, ethylene glycol poisonings normally occur by ingestion. O Ethylene glycol rapidly degrades In the environn~nt.
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From page 353... ...
Ethylene glycol is rapidly absorbed by the gastrointestinal tract, less rapidly by the lungs, and slowly through the skin. Because of ethylene glycol's low vapor pressure, inhalation is generally not associated with toxicity, although necrologic symptoms including nystagmus and syncope were reported in factory workers chronically exposed to vapor from heated ethylene glycol.
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From page 354... ...
2COH I HOCCOH NH2CH2COH OH I Oxalic Acid Glycine a-Hydroxy-~-ketoadipic Acid Other Pathways Oxalomalic Acid Formic Acid + Carbon dioxide Hydroxy -a- ketoglutaric Acid Adapted from Hall AH. Ethylene glycol and methanol: poisons with toxic metabolic activation.
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From page 355... ...
(Lactic acid formed during the metabolism of ethylene glycol to oxalic acid also contributes to the metabolic acidosis in patients poisoned by this glycol.) Ethylene glycol poisoning typically has three phases (Table 1~.
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From page 356... ...
Phase 3, which begins 24 to 72 hours after ingestion, can be manifested by a profound metabolic acidosis. Deposition of calcium oxalate crystals in the kidneys can lead to acute renal failure (irreversible in some cases)
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From page 357... ...
O Patients who have ethylene glycol poisoning characteristically have an elevated anion gap and osmolal gap. Several case reports of acute ethylene glycol poisoning have described effects on cranial nerves (e.g., facial paralysis, hearing loss, and bilateral visual disturbances)
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From page 358... ...
Although studies in humans have not specifically addressed effects on the fetus, adverse reproductive or developmental outcomes in humans have not been reported. O Nephrotoxicity is the dominant effect of serious ethylene glycol poisoning.
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From page 359... ...
Only four conditions will cause metabolic acidosis and elevate both the anion and osmolal gapsmethanol poisoning, ethyleneglycol poisoning, alcoholic ketoacidosis, and diabetic coma. However, when large quantities of ethanol are ingested concomitantly with ethylene glycol, enzymatic conversion to toxic metabolites that produce metabolic acidosis will be inhibited.
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From page 360... ...
Profound metabolic acidosis may be present. O Patients with ethylene glycol poisoning may initially appear inebriated and may lack severe toxic manifestations.
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From page 361... ...
These necrologic sequelae are usually found when treatment is delayed or inadequate. Laboratory Tests The abnormal laboratory findings in ethylene glycol poisoning include an elevated anion-gap metabolic acidosis, an increased osmolal gap, elevated serum ethylene glycol level, calcium oxalate or hippurate crystalluria, and sometimes, hypocalcemia.
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From page 362... ...
When the ingestion is recent, measures to prevent ethylene glycol absorption O Correction of metabolic acidosis is an important part of treatment in ethylene glycol poisoning.
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From page 363... ...
Specific treatment for ethylene glycol poisoning consists of sodium bicarbonate to correct the metabolic acidosis, ethanol to competitively inhibit conversion of ethylene glycol to its more toxic metabm lites, and hemodialysis to remove ethylene glycol and glycolic acid. Although this treatment regimen is effective in most cases, renal failure and death can occur if treatment is delayed.
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From page 364... ...
Hemodialysis should be considered if serum ethylene glycol levels exceed 50 mg/dL, if severe acid/base or fluid/electrolyte disturbances persist despite decontamination and ethanol therapy, or if renal failure develops. Hemodialysis should be continued until acidosis is controlled and the serum ethylene glycol level is in the 10 to 15 mg/dL range.
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From page 365... ...
Potential ethylene glycol exposure sources for the child could not be identified. (7J How will you treat the child ?
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From page 366... ...
has approved ethylene glycol as a component of adhesives used in packaging. State Guidelines Some states have defined acceptable ambient air concentrations for ethylene glycol ranging from zero for California to the Texas standard of 1.4 ppm (3.9 mg/m3)
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From page 367... ...
Biologic Fate Propylene glycol toxicity has been reported only rarely and in unusual circumstances involving medical applications such as intravenous injection or prolonged dermal contact during treatment of burns. (See Physiologic Effects, page 19.)
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From page 368... ...
O Large doses and unusual circumstances are necessary for the development of propylene glycol toxicity. O Propylene glycol poisoning is marked initially by CNS depression and an elevated osmolal gap, and later by an increased anion gap.
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From page 369... ...
Sources of /nformefion More information on the adverse effects of ethylene glycol and propylene glycol and treating cases of exposure to these glycols can be obtained from ATSDR, your state and local health departments, and university medical centers. Case Studies in Environmental Medicine: Ethylene/Propylene Glycol Toxicityis one of a series.
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From page 370... ...
The man's problem list includes ataxia, vomiting, agitation, disorientation, hyperventilation, and an elevated anion-gap metabolic acidosis. The child's problem list includes somnolence, ataxia, mental status changes, vomiting, hypoglycemia, low body temperature, and an anion-gap metabolic acidosis.
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From page 371... ...
(8) Information about health effects and standards and regulations can be obtained from the Technical Report for E~ylene/Propylene Glycolavailable from the Agency for Toxic Substances and Disease Registry (ATSDR)
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