USMLE-Rx Step 1 Practice Q's

USMLE-Rx Step 1 Qmax Challenge #1606

Check out today’s Step 1 Qmax Question Challenge.

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A 47-year-old man is brought to the emergency department after an apartment fire. He is complaining of headache, weakness, and vertigo. Physical examination is significant for confusion. The patient is treated with high-flow oxygen, sodium nitrite, amyl nitrite, sodium thiosulfate, and admitted for observation. The lab workup excluded the possibility of carbon monoxide toxicity.

Which of the following laboratory findings would be most consistent with this patient’s presentation?

A. A non-anion-gap acidosis
B. An abnormally low lactate level
C. An unexpectedly low level of venous oxygen saturation
D. Arterial blood gas analysis showing a pH of 7.2
E. Depressed arterial oxygen saturation
F. Increased arterial-venous oxygen gradient
G. Metabolic alkalosis

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3 replies »

  1. Dx would probably by CN- poisoning due to fire.
    Rx as given is Nitrite and Sulfur.
    Nitrite as desired would cause Methemoglobinemia (desired for management of CN- poisoning). It would cause shift to left and decreased O2-saturation.

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