Initial Check

Course: WB 4342
CE Original Date: March 20, 2020
CE Renewal Date: March 20, 2022
CE Expiration Date: March 20, 2024
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Instructions

This Initial Check will help you assess your current knowledge about ethylene glycol toxicity. To take the Initial Check, read the case below and then answer the questions that follow.

Case Study, First Patient
Disorientation, Ataxia, and Abdominal Symptoms in Visitors to a Municipal Airport

A 67-year-old man arrives at the emergency department (ED) of a small community hospital where you are the family physician on call. The patient is experiencing

  • ataxia,
  • dizziness, and
  • vomiting.

He is hyperventilating. On physical examination, the patient appears well nourished, but agitated and disoriented. He has no odor of ethanol on his breath.

Vital Signs

The patient’s vital signs are as follows:

  • Blood pressure (BP): 120/80 mm Hg
  • Temperature: 98.5°F
  • Pulse: 80 beats/minute
  • Respirations: 40 breaths/minute

Neurologic examination is otherwise normal, with no focal findings, particularly no nystagmus. Abdominal examination is normal.

Additional Information

The patient’s friend brought him to the ED. The friend said that late the previous night the patient complained of dizziness and had begun to vomit. The patient was hyperventilating in the morning and continued to vomit. Both men are retired pilots who teach at the local airport’s ground school. The friend wonders whether the food at the airport cafeteria was responsible because two other people collapsed at the airport that morning and were taken by ambulance to another hospital. Both the friend and the patient ate hot dogs and coleslaw from the cafeteria, but the friend states that he feels fine.

Results of Laboratory Tests
  • Blood ethanol and routine urine drug screen are negative.
  • Arterial blood gases (ABG) results: pH 7.10; PaCO₂ = 20 mm Hg; PaO₂ = 95 mm Hg; and bicarbonate = 8 mEq/L.
  • Sodium: 145 mmol/L (normal 135–145 mmol/L).
  • Potassium: 3.8 mmol/L (normal 3.1–5.3 mmol/L).
  • Chloride: 105 mEq/L (normal 98–109 mEq/L).
  • BUN: 20 mg/dL (normal 8–18 mg/dL).
  • Creatinine: 1.0 mg/dl (normal 0.6–1.2 mg/dL).
  • Glucose: 80 mg/dl (normal 65–110 mg/dL).
  • Calculated anion gap: 32 (normal 12–16).

Note that results might vary from laboratory to laboratory and depend on the elevation above sea level (see Table 1).

Table 1. Arterial blood gases – Ranges Considered Within Normal Limits at Sea Level and Breathing Room Air.
Partial pressure of oxygen (PaO2) 70–100 millimeters of mercury (mm Hg)
Partial pressure of carbon dioxide (PaCO2) 35–45 mm Hg
pH 7.35–7.44
Bicarbonate (HCO3) 21–28 milliequivalents per liter (mEq/L)
Oxygen content (O2CT) 15%–23% (15–23 milliliters [mL] per 100 mL of blood)
Oxygen saturation (O2Sat) 95%–100%
Case Study, Second Patient

Fewer than 30 minutes later, a 4-year-old boy arrives at the ED. On examination, you find a sleepy but responsive child who shows no evidence of trauma or focal neurologic signs. Abdominal examinations are normal.

Vital Signs

The patient’s vital signs are as follows:

  • BP: 94/76 mm Hg
  • Rectal temperature: 98.5°F
  • Respirations: 12 breaths/minute
  • Pulse: 78 beats/minute
Additional Information

The parents tell you they were attending a local fliers’ club luncheon at the airport. When they noticed the child staggering and incoherent, they rushed him to the ED. On the way, he vomited in the car.

Results of Laboratory Tests

You order the same laboratory tests for the child that you ordered for the 67-year-old patient. The tests reveal that the child is

  • hypoglycemic,
  • has slight acidosis, and
  • has an anion gap of 13.
Additional Information

You contact the local health department. They tell you they are investigating the earlier incidents at the airport. They have not identified the contaminant, but they suspect the airport’s water supply is contaminated.

Initial Check Questions
  1. What would you include in the problem list for each patient? What is the differential diagnosis for an anion gap metabolic acidosis?
  2. What additional tests, if any, will you order for these patients?
  3. How will you initially treat these patients?
  4. What questions would health department investigators ask airport visitors and employees to establish the exposure source?
  5. While repairing the water supply system, construction crews at the airport inadvertently connected the heating system water supply to the drinking water system. The concentration of ethylene glycol measured at the cafeteria’s water source was 9% (90,000 parts per million [ppm]). The U.S. Environmental Protection Agency (EPA) has an ethylene glycol drinking water quality guideline of 7 ppm (FSTRAC 1990). The lethal dose of 95% ethylene glycol is about 100 mL for an adult or 1.4 mL/kg.

    Who in the case study might be at risk of adverse health effects? Explain.

  6. An airport employee comes to your office a week after the water contamination incident. One of his jobs is to de-ice aircraft. A major spill occurred on the previous day, drenching him with de-icing fluid. He knows that de-icing agents contain large amounts of ethylene glycol. Immediately after the spill, he showered and changed clothes. He is worried about possible adverse health effects, such as cancer. What will you tell him?
  7. A pregnant airport worker consults you because she drank tea brewed with the contaminated water at the airport. Although she drank only a small amount of tea and had no ill effects, she is worried that even that small amount of contaminant will adversely affect her fetus. How will you counsel her?
  8. You later learn that during dinner at the cafeteria, the 67-year-old man drank several cups of coffee, while his friend, who did not become ill, drank only canned soda. The serum ethylene glycol level for the 67-year-old patient is 55 mg/dL; the anion gap is 35. How will you treat the 67-year-old patient?
  9. The child’s ethanol level is 85 mg/dL. You repeat the ethanol test, and again the result is high. The parents are incredulous. They state the luncheon did include wine and cocktails, but they did not supervise the child closely. Potential ethylene glycol exposure sources for the child were not immediately identifiable. How will you treat the child?
Initial Check Answers
  1. The man’s medical problems include the following:
    • Ataxia
    • Vomiting
    • Agitation
    • Disorientation
    • Hyperventilation
    • Elevated anion-gap metabolic acidosis

    The child’s medical problems include the following:

    • Somnolence
    • Ataxia
    • Mental status changes
    • Vomiting
    • Hypoglycemia
    • Low body temperature
    • Slight anion-gap metabolic acidosis

    Differential diagnoses include toxic alcohol ingestion and diabetic or starvation ketoacidosis.

    (Table 3 shows common toxic agents associated with an elevated anion gap.)

  2. Additional testing of these patients should include the following:
    • Urinalysis
    • Complete blood count
    • Serum osmolality measured by the freezing-point–depression technique
    • Ethylene glycol and methanol levels
    • Ammonia, acetaminophen, and aspirin levels
    • Liver function

    Find more information for this answer in the “Clinical Assessment – Laboratory Tests” section.

  3. Because the critical ingestion occurred several hours ago, emesis or gastric lavage will be of little value, and activated charcoal will be ineffective. However, it is important to act promptly to correct the metabolic acidosis and to prevent further conversion of the remaining ethylene glycol into its toxic metabolites.

    Intravenous administration of the antidote, fomepizole, will inhibit further ethylene glycol metabolism. In the absence of both renal insufficiency and significant metabolic acidosis, fomepizole may be used without hemodialysis. Start hemodialysis if severe metabolic acidosis or renal failure develops.

    Find more information for this answer in the “How should patients exposed to ethylene glycol be treated and managed?” section.

  4. The most common sources of epidemic poisonings include
     
    • contaminated food,
    • beverages, and
    • water supplies.

     
    Incident investigators would ask about types of food and drink available at the airport. They would take a detailed history of food and beverage intake from the patients and all others at the airport. They would attempt to find a common factor that would include those who were ill and exclude those who did not become ill. Investigators can usually identify the exposure source or restrict the exposure source possibilities by gathering and statistically analyzing data from a large group of people.

    Find more information for this answer in the “Where is ethylene glycol found?” section.

  5. The lethal dose of antifreeze (95% ethylene glycol) is about 100 mL or 1.4 mL/kg, although amounts in the reported cases vary widely. A cup (240 mL) of the contaminated water would contain about 22 mL of ethylene glycol. This dose could cause significant toxicity. Even mild symptoms of ethylene glycol poisoning would be a concern for air traffic controllers and other airport personnel responsible for judgments affecting many lives. Healthcare providers should examine every employee and visitor who consumed beverages or food prepared with water at the airport.

    Find more information for this answer in the “Where is ethylene glycol found?” section.

  6. Absorption of ethylene glycol is minimal through intact skin and is not likely to lead to toxic effects. Because the patient showered and changed clothes immediately, it is unlikely he will experience toxic effects from the spill. In the case of chronic exposure during the de-icing process, few particles from a spraying device are likely to be inhaled, so inhalation of ethylene glycol would be minimal. Contact during the de-icing process would not contribute substantially to toxicity, especially if the exposed person wore protective clothing and respiratory protection. No studies were located regarding carcinogenicity in humans after exposure to ethylene glycol.

    Find more information for this answer in the Sections of “Where is ethylene glycol found?”, “What Are Routes of Exposure to Ethylene Glycol?”, and “What Are the Toxicological Effects of Ethylene Glycol Poisoning?”.

  7. You can inform the patient that studies in experimental animals indicate that ethylene glycol at the high, prolonged levels can cause developmental effects although no studies in humans specifically assess the effects of ethylene glycol on fetal development.

    Find more information for this answer in the “What are the toxicological effects of ethylene glycol poisoning?” section.

  8. The initial treatment is described in answer 3. Traditionally, an ethylene glycol level of 50 mg/dL was an indication for hemodialysis. However, some patients with normal renal function and no evidence of metabolic acidosis have been treated effectively with fomepizole, despite having ethylene glycol levels of 50 mg/dL. In the absence of both renal insufficiency and significant metabolic acidosis, fomepizole may be used without hemodialysis. Hemodialysis should be started if metabolic acidosis develops.

    Find more information for this answer in the “How should patients exposed to ethylene glycol be treated and managed?” section.

  9. The child could be intoxicated with ethanol alone or with ethanol and ethylene glycol. If intoxication is from ethanol only, carefully monitor blood glucose and ethanol until the intoxication resolves. If laboratory results indicate that ingestion of ethylene glycol occurred, the patient can be treated with fomepizole. The limited data available suggest that fomepizole, at the same dosage used for adults, is effective and well tolerated in pediatric patients. For many pediatric patients treated with fomepizole for ethylene glycol poisoning, hemodialysis might not be needed, despite high ethylene glycol concentrations and the presence of metabolic acidosis.

    Find more information for this answer in the “How should patients exposed to ethylene glycol be treated and managed?” section.

Page last reviewed: October 6, 2020