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Environmental Medicine: Integrating a Missing Element into Medical Education
Disorientation, ataxia, and abdominal symptoms in visitors to a municipal airport
A 67-year-old man is brought to 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, agitated, and disoriented. There is no odor of ethanol on his breath. His vital signs include blood pressure, 120/80 mm Hg; temperature, 98.5°F; pulse, 80 beats/minute; and respirations, 40 breaths/minute. Neurologic examination is normal, and there is no nystagmus. Abdominal and cardiorespiratory examinations are also normal.
The patient was brought to the ED by his friend, who relates that the patient said he felt dizzy and began vomiting late last night. This morning he was hyperventilating and continued to vomit. Both men are retired pilots who teach at the ground school at the local airport. Because two other people had collapsed at the airport that morning and were taken by ambulance to another hospital, the friend wonders if the food at the airport cafeteria is responsible. Both he and the patient had hot dogs and coleslaw; yet the friend states that he feels fine.
Although the friend insists that the patient drank only water all day, you order a blood ethanol level, as well as a drug screen, arterial blood gases (ABG), serum electrolytes, BUN, creatinine, and glucose. Blood ethanol and drug screen are negative, and ABG results reveal pH 7.10; Paco21 20 mm Hg; and Pao2 95 mm Hg. Other test results are sodium, 145 mEq/L; potassium, 3.8 mEq/L; chloride, 105 mEq/L; bicarbonate, 8 mEq/L; BUN, 20 mg/dL; creatinine, 1.0 mg/dL; and glucose, 80 mg/dL. The calculated anion gap is 32 (normal 12 to 16).
Less than 30 minutes later, a 4-year-old boy is brought to the ED. On examination, you find a sleepy but arousable child. There is no evidence of trauma or focal neurologic signs. Abdominal and cardiorespiratory examinations are normal. Vital signs include rectal temperature, 97.8°F; respirations, 12 breaths/minute; pulse, 78 beats/minute; BP, 94/76 mm Hg. The parents tell you that they were attending a local fliers’ club luncheon at the airport. When they found the child staggering and incoherent, they rushed him to the ED; the child vomited in the car. You order the same laboratory tests for the child that you ordered for the 67-year-old patient. From the results of the child’s tests, you note that the child is hypoglycemic and slightly acidotic. You calculate an anion gap of 13.
You contact the local health department and are told that they are investigating the earlier incidents at the airport. They suspect that the airport’s water supply is contaminated, but they have not identified the contaminant.
(a) What would you include in each patient’s problem list? What is the differential diagnosis for an anion gap metabolic acidosis?