234.A 31-year-old man is brought to the ED by EMS who state that the
man was found lying on the floor of his garage. He is rousable in the ED,
speaks with slurred speech, and vomits. His BP is 140/85 mm Hg, HR is
94 beats per minute, temperature is 98.8°F, RR is 17 breaths per minute,
and oxygen saturation is 99% on room air. You place an IV line, draw
blood, and start a liter of normal saline running through the line. Labora-
tory results reveal serum sodium 139 mEq/L, potassium 3.5 mEq/L, chloride
101 mEq/L, bicarbonate 14 mEq/L, BUN 15 mg/dL, creatinine 1 mg/dL,
glucose105 mg/dL, arterial blood pH 7.27, COHb 4%, and lactate 2.8 mEq/L.
Urinalysis shows: 1+ protein, trace ketones, WBC 4/hpf, red blood cell (RBC)
2 to 3/hpf, and multiple envelope-shaped and needle-shaped crystals. Which
of the following conditions would best explain his metabolic acidosis?
a. Carbon monoxide (CO) poisoning
b. Ethylene glycol poisoning
c. Diabetic ketoacidosis
d. Lactic acidosis
e. Isopropyl alcohol poisoning
235.A 35-year-old man who is employed as a forklift operator was found
sitting outside of a warehouse. He came stumbling out complaining of
dizziness and headaches. Coworkers in an adjoining warehouse also com-
plained of headache and nausea. After collapsing outside, he regained
consciousness immediately but appeared confused. In the ED, his BP is
100/54 mm Hg, HR is 103 beats per minute, temperature is 100°F, and RR
is 23 breaths per minute. Physical examination is unremarkable. Labora-
tory results reveal WBC 10,500/μL, hematocrit 45%, platelets 110/μL,
sodium 137 mEq/L, potassium 4 mEq/L, chloride 103 mEq/L, bicarbonate
21 mEq/L, BUN 8 mg/dL, creatinine 0.5 mg/dL, and glucose 89 mg/dL. Arte-
rial blood gas results are pH 7.32, PCO 2 32 mm Hg, and PO 2 124 mm Hg.
Which of the following is the most likely diagnosis?
a. Methemoglobinemia
b. Hypoglycemic syncope
c. Hydrocarbon poisoning
d. Opioid overdose
e. CO poisoning
244 Emergency Medicine