General Pathology USMLE Step 1 Practice Question
A 23-year-old man is hospitalized with a femoral shaft fracture from a motorcycle collision. Thirty-six hours later, he develops tachypnea (RR 28/min), confusion, and a petechial rash over the chest and axillae. Vital signs show BP 110/68, HR 102/min, temperature 37.8°C, and SpO2 88% on room air. Arterial blood gas demonstrates hypoxemia (PaO2 65 mmHg). Chest X-ray shows bilateral infiltrates. He denies recent leg swelling. Which of the following is the most likely underlying process?
Answer choices
- ARelease of marrow fat into the circulation after fractureCorrect answer
- BAspiration of gastric contents
- CDiffuse alveolar hemorrhage due to anti basement membrane antibodies
- DNitrogen bubble formation in tissues
- EImmune complex deposition in pulmonary vessels
- FSeptic thromboembolism from bacterial colonization of the fracture site
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